The Impact of Various Land Use Strategies on Suburban Mobility
Click HERE for graphic.
Click HERE for graphic.
THE IMPACT OF VARIOUS LAND USE
STRATEGIES ON SUBURBAN MOBILITY
Final Report
Click HERE for graphic.
Prepared by:
MIDDLESEX SOMERSET MERCER REGIONAL COUNCIL
621 Alexander Road
Princeton, NJ 08450
and
HOWARD/STEIN-HUDSON ASSOCIATES, INC.
38 Chauncy Street
Boston, MA 02111
in association with:
ACUTECH, INC.
DOUGLAS AND DOUGLAS, INC.
MOORE-HEDER ARCHITECTS, INC.
NOTICE:
This document is disseminated under the sponsorship of the U. S.
Department of Transportation in the interest of information exchange.
The United States Government assumes no liability for its contents or
use thereof.
The United States Government does not endorse manufacturers or
products. Trade names appear in the document only because they are
essential to the content of the report.
Middlesex Somerset Mercer Regional Council (MSM)
621 Alexander Road, Princeton, NJ, 08540. (609) 452-1717
MSM is an independent, non-profit civic planning and research
organization. Established in 1968, MSM concentrates on land use,
transportation, housing, environmental conservation, and related
issues in the 500-square-mile central New Jersey region situated
between the Delaware and Raritan Rivers, MSM's research and advocacy
programs are supported primarily by individual and corporate members
who share a concern for the future of their region. MSM receives
funding from foundations and the state and federal governments to
carry out special projects.
ACKNOWLEDGMENTS
The preparation of this report has been financed by the Urban Mass
Transportation Administration's Office of Technical Assistance and
Safety, the New Jersey Department of Transportation, the Fund for New
Jersey, and the Hyde and Watson Foundation, and the members of
Middlesex Somerset Mercer Regional Council.
The contents of this report reflect the views of the MSM staff and
their consultants, who are responsible for the facts and accuracy of
the information presented herein. The contents do not necessarily
reflect the views of any of the above funding sources.
The MSM staff and their consultants would like to acknowledge the
assistance and guidance given them by the study's Steering Committee
and Peer Review Panel. In addition, MSM would like to give special
recognition to Edward Thomas, Director of Technical Assistance and
Safety of the Urban Mass Transportation Administration in Washington,
DC, for his vision and support for this project.
The Steering Committee included the following individuals:
Chairman: David J. Goldberg, Esq., Cohen, Shapiro, Polisher,
Sheikman & Cohen, and Chairman, NJ Turnpike Authority
William S. Beetle, New Jersey Department of Transportation
Ronald Berman, Esq., DKM Properties, and MSM Board of Directors
Martin Bierbaurn, Esq., New Jersey Office of State Planning
Hon. Carolyn Bronson, Freeholder, Mercer County
Jack Claffey, Delaware Valley Regional Planning Commission
Hon. David B. Crabiel, Freeholder, Middlesex County
Robert Dunphy, Urban Land Institute
Carl Hintz, AICP, ASLA, Hintz Associates, Inc.
David Knights, Princeton Forrestal Center
Jack Lowenstein, FMC Corporation
William Swain, MSM Board of Directors
Joel S. Weiner, North Jersey Transportation Coordinating Council
Jeffrey Zupan, Transportation Consultant, Regional Plan Association
The Peer Review Panel included the following:
Frederick Ducca, Federal Highway Administration
Robert Dunphy, Urban Land Institute
Kevin Hooper, JHK Associates
Patrick Kane, Architect
Richard Pratt, Consultant
Richard Tustian, Lincoln Institute of Land Policy
Jeffrey Zupan, Transportation Consultant, Regional Plan Association
Staff of MSM who worked on this project included:
Administrative Project Manager:
Dianne Brake, President, MSM
Technical Project Manager:
Melvin R. Lehr, P.E., Principal, M. R. Lehr & Associates, and
Secretary, MSM Board of Directors
Senior Research Director:
Donna Bender, AICP/PP, Vice-President, MSM
Consultant Team included:
Howard/Stein-Hudson Associates, Inc.
Jane Howard, Principal
Arnold J. Bloch, Ph.D., Project Manager
Alfred R. Howard, P.E., Sr. Project Engineer
Douglas & Douglas, Inc.
G. Bruce Douglas, Ph.D., P.E., Principal
Barry Zimmer, Transportation Planner
Acutech, Inc.
Ruby Siegel, President
Heder Architects, Inc.
LaJos Heder, Principal
Staff members of the Bureau of Local Transportation Planning of the
New Jersey Department of Transportation also made important
contributions to this project. MSM gratefully acknowledges the
technical and administrative assistance of:
William S. Beetle, Manager, Bureau of Local Transportation Planning
Helene K. Rubin, PP/AICP, Principal Planner, Bureau of Local
Transportation Planning
James B. Lewis, PP, Supervising Planner
James Pivovar, Manager, Bureau of Transportation and Corridor Analysis
THE IMPACT OF FUTURE LAND USE SCENARIOS
ON SUBURBAN MOBILITY
EXECUTIVE SUMMARY
MSM Regional Council and its team of technical consultants have
completed an 18-month study on the interaction between suburban land
use trends and regional traffic conditions. The results of the study
verify what had previously been only a theoretical viewpoint: that
concentrating new suburban development into higher density, mixed-use
centers will slow the growth of regional vehicular use.
The study tested the traffic impact of locating the region's new
employees in Trenton and New Brunswick, as well as in tightly
clustered suburban employment centers. Under scenarios proposed in
the study, new residents would work and shop closer to their homes.
Their living environment would be conducive to walking and reduced
auto use. Those who still commute longer distances would have transit
and ridesharing opportunities available to them, and a significant
number would take advantage of these choices because of incentives
provided by regional demand management policies. The study
demonstrated that this approach to land use would create a significant
reduction in the growth in traffic.
Background:
MSM began this study in the summer of 1989 by reviewing the
published data on the relationship between suburban development and
transportation, as well as by evaluating various analytic tools for
the study. A consultant team joined MSM in February 1990, and a
steering committee and peer review panel comprised of transportation
and land use professionals (listed in Acknowledgments) provided
oversight for the project.
Constructs of Higher Density, Mixed-Use Centers:
The study team developed and tested three models -- or "constructs"
-- of higher density, mixed-use centers designed to fit within the
suburban setting of the MSM region. These constructs incorporated
residential and employment growth expected in the region by 2010 -- a
30 percent increase in population (187,905 new residents) and a
dramatic 54 percent increase in employment (182,581 new jobs) -- but
reshaped that growth into different land use configurations. The new
growth was located in the cities and in a small number of newly
created suburban centers instead of in low density developments spread
throughout the region.
Three construct types were used: a Transit Construct, a dense
development that could house a minimum of 12,000 people and employ
over 13,000, while maximizing transit, ridesharing and walking access;
a Short Drive Construct, a somewhat less dense area of at least 6,700
residents and 9,500 employees, with ridesharing and walking as the
main travel alternatives to the single occupant vehicle (SOV); and a
Walking Construct, a dense, pedestrian-oriented residential village of
about 4,500 persons with only minimal service and retail employment
opportunities.
Developing a Transportation Modeling Procedure:
A transportation modeling package called TransCAD was used for its
capacity to incorporate important land use elements in a Geographical
Information System (GIS). This allowed the project team to utilize
transportation models similar to those used in prior regional studies
(e.g., Route 1 Corridor Study, NJDOT, 1986) in combination with land
use/demographic data bases and models that will have long-range
applications for MSM, the counties, and the municipalities.
A key part of the modeling process was to determine quantitatively
how much less auto travel could be expected from the constructs.
Using case study data, the study team determined that Transit
Constructs would create 28 percent fewer vehicle trips than the same
amount of development dispersed in less dense, single-use
configurations. For Short Drive and Walking Constructs, the
corresponding numbers were 24 percent and 18 percent fewer vehicle
trips, respectively.
Scenarios and Results
Two scenarios were developed. Scenario 1 assumed that all new
regional development between the year 1988 and 2010 would be
distributed in two ways. First, much of it would be absorbed into
suburban constructs located throughout the region. Second, a major
resurgence of growth would, occur in Trenton and New Brunswick. In
Scenario 2, no major resurgence of the region's cities was assumed.
Instead, all growth would be absorbed into the suburban constructs,
making them larger than those in Scenario 1.
The results for two key criteria are described and displayed in the
discussion below.
Vehicle Trips
The figure on the right examines the growth rate of vehicle trips
occurring in the suburban portion of the MSM region between 1988 and
2010. Under "non-construct," trend conditions, new daily vehicle
trips in the suburban area would be expected to grow by nearly 1.8
million. In Scenario 1, the combination of constructs and strong urban
growth reduces that suburban growth to under 700,000 daily trips.
In Scenario 2, where there is no significant new urban growth, new
suburban vehicle tripmaking still declines to about 1.2 million daily
trips.
When adding the large number of existing trips to these varying
levels of new trip growth, the results for 2010 are as follows:
- There would be 18 percent fewer total daily suburban vehicle
trips in Scenario 1, compared to the trend;
- and 10 percent fewer total daily suburban vehicle trips in
Scenario 2, compared to trend.
Click HERE for graphic.
Vehicle Miles Traveled
As seen at right, the growth of new vehicle miles traveled (VMT) on
the suburban regional highway network declines in the alternative
scenarios. Under trend conditions, VMT grows by about 300,000 miles
during the morning peak hour trip to work. Under Scenario 1, the
growth of AM peak hour VMT is under 170,000 miles. In Scenario 2, the
growth is slightly more than 200,000 miles.
When the existing VMT are added to these varying levels of new VMT
growth, the results are as follows:
- In the year 2010, there would be 12 percent less total VMT
in the morning peak under Scenario 1, compared to the trend;
- and 9 percent less total VMT in Scenario 2, compared to the
trend.
Click HERE for Graphic
Conclusions
Four basic conclusions can be drawn from the analyses performed in
this study:
1. Mixed-use centers can produce significant regional
transportation benefits.
2. Mixed-use centers are a viable concept for suburban settings.
3. Mixed-use centers, through design and function, can have
tangible transportation benefits at the site.
4. Promoting strong urban growth along with suburban mixed-use
centers gives the best regional transportation results.
Note: These dramatic results are based on the assumption that all
new development locates in cities or in higher density, mixed-use
constructs. Only to the extent that we can change our current land
use patterns, will we approach these results. Success within the
next twenty years is unlikely because of the number of new
developments in the region that already have planning permits for
traditional, low density, single-use patterns. Success in the
future will be achieved by carefully planning uncommitted lands and
by redeveloping existing sites over a much longer period of time.
Next Steps:
In this study, the project team has worked to see whether higher
density, mixed-use suburban development can achieve traffic impact
reduction on a regional level. The conclusion is that indeed it can.
During the next phase of our Land Use/Transportation Study, once again
funded by the Urban Mass Transportation Administration, MSM will
present this evidence to local officials, employers, developers, and
residents and relate it to their efforts to achieve the goals and
objectives of the New Jersey State Development and Redevelopment Plan
and the federal Clean Air Act. Phase Two is expected to be completed
by December, 1992.
Financial and time constraints on the first phase of the study
forced the project team to ignore several key technical issues. Our
regionwide trip generating formulas concentrated on suburban practices
and do not provide a good reflection of urban tripmaking conditions.
During the next phase of study, in order to understand better the full
regional and subregional consequences of constructs and strong urban
growth, new formulas will be developed and urban area vehicle trip
reduction factors devised. In addition, a more detailed network and
zone structure for the urban areas will be built to better distribute
tripmaking within and around the periphery of the cities.
THE IMPACT OF FUTURE LAND USE
SCENARIOS ON SUBURBAN MOBILITY
TABLE OF CONTENTS
Page
I. INTRODUCTION
A. Impetus for the Study 1
B. The Study Area 2
C. Goals and Objectives of the Study 2
D. Methodology 2
1. Study Participants 2
2. Study Process 4
II. BUILDING BASIC CONSTRUCTS OF MIXED-USE CENTERS 7
A. Suburban Development Trends and Alternatives 7
1. The Constructs as Alternatives to Present Development Trends 7
2. The Problems with Existing Development Trends 7
3. The Princeton Forrestal Center Area: An Attempt to Achieve
Mixed-Use Center Objectives 7
4. Why Propose Alternative Development Patterns? 8
B. Defining Alternative Development Patterns: The Construct
Approach 11
1. Three Basic Construct Types 11
2. Urban Design Components of the Three Constructs 16
3. Key Characteristics of the Constructs 22
C. The Role of Constructs in Reducing Vehicle Traffic: Local Level
Analysis 24
1. Assumptions 24
2. Methodology 25
3. Construct Land Use and Transportation Relationships 25
4. Determination of Vehicle Trip Reduction Factors 26
5. Producing a Vehicle Trip Reduction Factor: An Example 29
III. DEVELOPING THE REGIONAL TRANSPORTATION MODEL 32
A. Basic Components of the Regional Transportation Model 32
1. Building the MSM Network with Reliance on Previous Efforts 32
2. Using the GIS-Based TransCAD Package 32
3. Accounting for the Traffic Reduction Effects of Construct
Development in the Regional Model 33
B. Building the MSM Network with Reliance on Previous Efforts 33
1. Building the 1988 Network 33
2. Building the 2010 Network 35
3. Building Traffic Zones 36
4. External Trips 36
C. Using the GIS-Based TransCAD Package 36
D. Accounting for the Traffic Reduction Effects of Construct
Development in the Regional Model 37
IV. FORECASTING DEVELOPMENT SCENARIOS 39
A. Developing 1988 Baseline Conditions 39
B. Year 2010 Trend Conditions 39
C. Alternative Development Scenarios 41
1. Scenario 1: Constructs and Major Urban Growth 41
2. Scenario 2: Constructs With Only Trend Urban Growth 43
V. ANALYZING THE TRANSPORTATION IMPACTS OF CONSTRUCT SCENARIOS 49
A. Defining the Study Area 49
B. Regional Impacts of the Scenarios 49
1. Total Vehicle Trips on the Regional Network 49
2. Total Vehicle Miles on the Regional Network 51
3. Travel Speeds 55
4. Travel Time 56
VI. CONCLUSIONS AND NEXT STEPS 58
A. Conclusions 58
1. Mixed-Use Centers Can Produce Significant Regional
Transportation Benefits 58
2. Mixed-Use Centers are a Viable Concept for Suburban
Centers 59
3. Mixed-Use Centers, Through Design and Function, Can Have
Tangible Transportation Benefits at the Site 60
4. Promoting Strong Urban Growth Along with Suburban Mixed-Use
Centers Gives the Best Regional Results 60
B. Next Steps 60
1. Technical Improvements to the MSM Model and the Regional
Network 61
2. Quantifying the Public and Private Costs and Benefits of the
Study Findings 61
3. Seeking Public Support for Changing Regional Development
Patterns 62
REFERENCES
APPENDICES:
Appendix A. Calculation of Vehicle Trip Reduction Factors for Walking,
Transit, and Short Drive Constructs
Appendix B. MSM Region Traffic Zones and 1988 Calibration Network
Appendix C. TransCAD Package Steps and Trip Generation Equations
Appendix D. Development of Land Use Data for Municipalities and Zones
Appendix E. MSM Employment and Housing Projections, Vehicle Trip
Productions and Attractions, Daily Trip Ends, and
Jobs/Housing Ratios: 1988, 2010 Trend, Scenario 1,
Scenario 2
Appendix F. Vehicle Trips, Speeds, and Vehicle Miles of Travel for
Study Area Municipalities: 1988, 2010 Trend, Scenario 1,
Scenario 2
Appendix G. Suburban Mixed-Use Centers and Transportation: Current
Research and Issues
MSM Regional Council Report, June 1990
LIST OF TABLES
Page
Table 1: MSM Land Use Construct Comparison 23
Table 2: Summary of Trip Reduction Factors 30
Table 3: 1988 Baseline Conditions for MSM Region Municipalities 40
Table 4: 2010 Trend Conditions for MSM Region Municipalities 42
Table 5: Location of Constructs in Both Scenarios 1 and 2 45
Table 6: Current and Projected Employment Under Different Scenarios 47
Table 7: Current and Projected Households Under Different Scenarios 48
Table 8: Vehicle Trips in the MSM Construct Study Area 52
Table 9: A.M. Peak Hour Vehicle Miles Travelled (VMT) in the MSM
Construct Study Area 54
Table 10: A.M. Peak Hour Vehicle Speeds in the MSM Construct Study
Area 55
Table 11: A.M. Peak Hour Vehicle Travel Minutes in the MSM Construct
Study Area 56
LIST OF FIGURES
Page
Figure 1: The MSM Region 3
Figure 2: Representative Recent Development - Forrestal Center 9
Figure 3: Forrestal Village - Existing Development 10
Figure 4: Transit Construct City, Diagram 13
Figure 5: Short Drive Construct City Diagram 14
Figure 6: Walking Construct Village Diagram 16
Figure 7: Transportation Components of Constructs - Generalized 17
Figure 8: Diagrammatic Cross Section - Town Center 18
Figure 9: Diagrammatic Cross Section at Railroad Station
and Main Street 19
Figure 10: Diagrammatic Cross Section - Highway Edge 20
Figure 11: Ratio of Construct Total Trips Compared to Same Construct
with Trend Rate 31
Figure 12: Chart of Study Process 36
Figure 13: Location of Constructs in the MSM Region 44
Figure 14: Employment and Household Projections for Trenton and New
Brunswick for the Year 2010 under Scenarios 1 and 2 46
Figure 15: Growth in Daily Trip Ends 1988 to 2010 - MSM Construct
Study Area: Trend Versus Alternative Development
Scenarios 50
Figure 16: Growth in AM Peak Hour Vehicle Miles of Travel 1988-2010 -
MSM Construct Study Area: Trend Versus Alternative
Development Scenarios 53
Figure 17: Growth in Travel Time 1988-2010 (Vehicle Minutes of
Travel) - MSM Construct Study Area: Trend Versus
Alternative Development Scenarios 58
CHAPTER 1:
INTRODUCTION
A. Impetus for the Study
The continued growth of the nation's suburban areas as residential
and employment centers places a strain on the transportation
infrastructure and services available in these areas. As the 1989
report by the Institute of Transportation Engineers entitled A Toolbox
for Alleviating Traffic Congestion pointed out, the growing trend of
suburban congestion is due to 1) more people traveling in metropolitan
areas (with most of that growth occurring in suburban settings); 2)
more people traveling by car (and, overwhelmingly, in single occupant
vehicles); 3) more people traveling to dispersed locations; and 4)
more people traveling where necessary highway capacity has not been
provided.
The strain that this creates is manifested by added energy use and
regional air pollution, added congestion and delay; and the increasing
conflict between preserving suburban/rural lifestyles and the need for
more highway capacity and traffic controls.
Suburban growth represents a 40-year trend, and there is no
expectation of any significant reversal leading to reconcentrated
urban areas. In that light, the focus among planners has turned to
determining how to redistribute and redesign suburban development to
conserve open lands, preserve the unique local character of villages
and towns, and reduce growth in traffic congestion, while continuing
to serve the diverse needs of residents and employees.
In its April, 1989 report to the Urban Land Institute entitled
Suburban Mobility and Growth Management: Initiatives in Central New
Jersey, Middlesex Somerset Mercer (MSM) Regional Council concluded
that "concentrating growth in higher density, mixed-use centers" would
be "expected to reduce the growth in vehicular traffic" in this
suburban New Jersey setting. The report pointed out that
concentrating growth would create other related advantages:
- The reduction of highway congestion by internalizing trips
within mixed-use areas;
- making transit or paratransit more feasible; and
- reducing the length of necessary trips.
The report acknowledged that "the real impact of these centers on
traffic reduction has yet to be tested." The MSM Land
Use/Transportation Project provides the evidence to document the
transportation advantages of centers.
1
B. The Study Area
The MSM region served as the study area for the Land
Use/Transportation Project. It is a 523-square mile area, consisting
of 32 municipalities covering all of Mercer County and the southern
portions of Middlesex and Somerset Counties in central New Jersey (see
Figure 1 on page 3). Virtually halfway between New York City and
Philadelphia, the MSM region is largely suburban, although its
northeast and southwest borders are anchored by the cities of New
Brunswick (about 40,000 people) and Trenton (about 90,000 people),
respectively. The Borough of Princeton (about 12,000 people) is at
the center of the MSM region.
The MSM region is bisected -- northeast to southwest -- by Route 1,
a four-lane regional commuter highway characterized by some strip
development, stop lights, shopping centers and office parks. New
Jersey's Department of Transportation has a long-term plan to improve
Route 1 to six lanes and to replace most of the lights with grade-
separated intersections. The Northeast Corridor Rail Line, used both
by New Jersey Transit commuter trains and AMTRAK intercity lines,
parallels Route 1.
In 1988 - the year used in this report as the base year because of
data availability - it was estimated that the region included more
than 617,000 residents and nearly 338,000 jobs (source: New Jersey
Department of Labor). Growth by the year 2010, as projected in the
1989 New Jersey Preliminary State Development and Redevelopment Plan,
is dramatic -- 187,905 new residents (a 30% increase), and 182,581 new
jobs (a 54% increase).
C. Goals and Objectives of the Study
The goal of the MSM Land Use/Transportation Study was to rigorously
test the concept of higher density, mixed-use centers in the suburban
setting, in order to assess the type and level of transportation
benefits that might occur.
The specific questions that this study addressed are as follows:
- Can higher density, mixed-use centers produce noticeable,
beneficial effects on the regional highway network, when
compared to the effects of typical single purpose suburban
development as characterized by current trends?
- What intensities of development and mixes of land use patterns
can realistically be developed that reduce vehicular trips made
to, from and within the centers?
- Can higher density, mixed-use centers be located realistically
in the MSM region, given expected growth in employment and
population levels?
D. Methodology
1. Study Participants
The study was conducted in a collaborative effort by MSM Regional
Council, its consultant team, and staff members of the Bureau of Local
Transportation Planning of the New Jersey Department of Transportation
(see Acknowledgments).
A steering committee was created early in the study and was
convened four times during the course of the study (November 27, 1990;
June 13, 1990; January 23, 1991; and April 10, 1991). The committee
had the opportunity to review and comment on interim products, as well
as to ask questions of and make comments to the project team at the
committee's meetings.
2
Click HERE for graphic.
3
In addition, a peer review process was built into the study at two
important junctures of the project. First, on May 14-15, 1990, a
meeting was held between the project team and a peer review panel. At
this meeting, the overall methodological direction of the study was
discussed, highlighting the following key issues (discussed in detail
later in this report):
- The TransCAD software used for modeling transportation impacts;
- The "constructs" and "scenario" approach for testing land use
patterns;
- Site planning to reduce vehicular use; and
- Travel demand management policies and effectiveness.
At the second juncture - during November and December of 1990 -- a
key interim document describing the capabilities of constructs to
reduce single occupant auto tripmaking was circulated for comment
among peer reviewers (Appendix A).
The comments of the peer review panel, as well as steering
committee members, were a valuable resource to the project team during
the course of the study.
2. Study Process
The study consisted of five major tasks, which are briefly
described below and described in more detail later in this report.
a. Suburban Mixed-Use Centers and Transportation: Current
Research. (Appendix G)
To test the hypothesis that concentrating growth in mixed-use
centers would yield regional transportation benefits, the project team
began by exploring published research for evidence of interaction
between land use and transportation in general, and more specifically,
the travel behavior associated with different facets of existing
suburban mixed-use centers. Documented parameters for mixed-use
centers, such as proper density, scale, design and mix of activities,
were gathered as an empirical foundation for the analysis.
In addition, effective demand management techniques were examined
to determine the extent to which the benefits of changing land use
might be enhanced by implementing transportation management programs
(a reciprocal enhancement was expected).
Although the literature search did not uncover any hard and fast
rules, a number of case studies emerged which served as the basis for
crafting the prototype mixed-use centers.
b. Building Basic Constructs of Mixed-Use Centers. (Chapter II)
The theoretical concept of a higher density, mixed-use center was
formalized into a set of land use models, or "constructs." These
constructs were meant to be ambitious, yet realistic representations
of suburban centers which include good planning and design features,
especially a pedestrian environment while meeting the region's needs
for residential and employment growth.
Three types of constructs were formulated:
4
- The Transit Construct: A high density, mixed-use center with a
high concentration of employment. It is designed to maximize
the use of transit services and provide significant pedestrian
amenities.
- The Short-Drive Construct: A high density, mixed-use center,
somewhat lower in density than the transit construct, but also
with a high concentration of employment. Although there are
minimal transit services, there are significant pedestrian
amenities in this construct as well.
- The Walking Construct: A tightly clustered, mixed-use village or
town, with a high level of residential development and only
minimal employment opportunities.
c. Modeling the New Land Use/Transportation Relationships
(Chapter III)
A regional transportation model was developed for the purpose of
testing the effects of the constructs on travel in the MSM region.
The typical modeling system has four steps: 1.) trip generation: uses
formulas to generate total trips; 2) distribution: distributes trips
throughout the region; 3) mode split: defines the proportion of trips
using different forms of transportation; and 4) assignment: it assigns
vehicle trips to appropriate routes for traveling from place to place.
The modeling system used in this study is the TransCAD software
package which combines a geographic information system (GIS) with a
traditional four-step transportation planning model. This GIS
capability has a number of benefits. It provides numerous procedures
for processing land use data, constructing and subdividing traffic
zones, calculating the precise location and adjustment of
transportation network links, and summarizing traffic characteristics
by geographic area. It is also capable of storing present and future
land use and demographic data at the parcel, census block and
municipality level, a feature which is attractive to the long-term
planning efforts of MSM.
The modeling system was further adjusted by consideration of some
key tripmaking characteristics of the constructs, as distinct from the
other subareas of the region. For the region as a whole, auto trip
generation rates were developed using formulas developed by previous
NJDOT studies in and around the MSM region. But these rates were
adjusted for the different construct types -- based on case studies
and the team's planning judgment to develop "trip reduction factors" -
- to reflect the enhancing effect of density, demand management, mixed
uses and transit services on reducing regional auto use to and from
these constructs.
d. Forecasting Development Scenarios (Chapter IV)
A 1988 baseline of employment and population conditions in the MSM
region was established. A forecast year of 2010 was selected for
evaluation and a "2010 Trend Scenario" was developed, projecting
conditions similar to those in the base year to the year 2010. These
forecasts represent the trend of what is likely to occur in land use
and transportation conditions without any change in policy direction.
In addition, two alternative land use scenarios were developed for
the year 2010 to compare with the trend:
Scenario 1: a combination of suburban development in constructs and
increased employment and population growth in the rep-ion's major
cities;
5
Scenario 2: the replacement of all trend suburban development with
development in suburban constructs, and only trend growth in the
cities.
The two scenarios differ by the amount of growth which is allocated
to urban vs. suburban areas.
e. Analyzing the Transportation Impacts of Construct Scenarios
(Chapter V)
The impact of construct vs. trend development was analyzed,
focusing on four key indices of transportation conditions at the
regional and subregional level:
- The number of vehicle trips;
- The level of vehicle miles traveled (VMT);
- The level of delay experienced; and
- The average speed.
These measures were then assessed in aggregate terms -- what
happens in the suburban portion of the region overall -- and in
disaggregate terms, for their effects on suburban municipalities.
6
CHAPTER II:
BUILDING BASIC CONSTRUCTS OF MIXED-USE CENTERS
A. Suburban Development Trends and Alternatives
1. The Constructs as Alternatives to Present Development Trends
The constructs were devised as a means for exploring and
illustrating alternative development patterns for central New Jersey.
The dominant features of recent growth are large, single-use private
developments: office parks, shopping centers and subdivisions. These
developments are planned only within their property boundaries, and
are related to each other only by existing road connections, and are
almost entirely limited to automobile access.
The basic premise of the study is that integrated, multi-use and
better planned development can significantly reduce auto travel needs.
Underlying this premise are basic convictions that more integrated
land use planning and design is both desirable in terms of aesthetic,
social and environmental goals, and marketable to developers and
consumers.
2. The Problems With Existing Development Patterns
The rapid growth of the 1980's tended to create large-size
single purpose developments on assembled tracts of previously rural
land. These suburban developments - office parks over 6 million
square feet, shopping centers approaching 1 million square feet,
residential complexes over 3,000 units -- are much larger in scale
than the existing fabric of small towns in the area. They lack an
effective integration of uses and have no community framework to
support them.
This land use pattern forces total dependence on automobile travel.
By maximizing the need for cars and parking spaces at each
destination, this pattern causes each facility to be surrounded and
isolated by roads and parking lots, thereby reducing accessibility by
walking, transit or bicycle. These single function private
developments, although the size of small towns, lack a town's public
institutions such as schools and government facilities. The resulting
absence of public spaces and foot traffic not only aggravates
transportation problems, but prevents the evolution of community life.
3. The Princeton Forrestal Center Area: An Attempt to Achieve
Mixed-Use Center Objectives
The Princeton Forrestal Center is a major multi-use center owned
by Princeton University that, in 1975, set the standard for
development along the Route 1 Corridor. The center was selected by
the project team to illustrate some key design issues for this study.
The center is known for its ecologically sensitive site planning, as
well as its excellent examples of architectural design. It contains
all three of the major land use functions -- office, retail and
residential -- and has the potential for creating a more integrated
community environment such as that presented in the constructs.
7
Forrestal Village, a retail and office development within
Forrestal Center, offers a concrete illustration of how the
comparative advantages of mixed-use constructs can be evaluated
against the best efforts of single function development. In addition,
Forrestal Village represents a movement toward a mixed-use and town
center type environment, and, although it does not fully incorporate
the concepts of integrated land use proposed in the constructs, it can
provide some useful lessons.
The plan of the Forrestal Center area contains three basic
elements (as shown in Figure 2):
- The Forrestal Center office park, with 4.9 million square feet
of space already completed, and an eventual 8.6 million square
feet it build-out;
- Princeton Landing and several other residential clusters (the
latter not part of the development, but physically proximate)
totaling about 1,200 dwelling units;
- Forrestal Village, a regional shopping center with upper-floor
offices and a hotel, totaling about 1.5 million square feet of
which 822,000 square feet has been built, with the remainder
designated as office space.
The office buildings are driving oriented. The housing
complexes are exclusively residential, with only minimal community
recreation facilities, and are only accessible at a minimal number of
points. Even though the distances among the various facilities are
not great (many under a mile), there are no local connections other
than a very few regional roads.
Forrestal Village embraces some of the ideas of mixed-use
developments and traditional pedestrian- oriented town centers. It
contains a "Main Street," a 'Village Square" and a "Market Plaza." Its
environment fairly convincingly recreates the environment of
traditional town centers. In appearance the town center and main
street in one of the constructs might be very similar.
An aerial view of Forrestal Village (Figure 3) reveals a very
different place. It is isolated in a sea of parking lots and,
although it is located on a huge overpass of Route 1, it is virtually
inaccessible from anywhere else. The "Main Street" and "Village
Boulevard" terminate in parking lots within a block of the center.
Although an attempt was made to provide walkways and bikepaths, it is
inconvenient to walk or bike to the office park or the residential
neighborhood. There is no school or city hall nearby. Forrestal
Village is revealed from this view as simply a regional shopping
center with the marketing theme of a "village" without the urban
design and land use connections to make it real.
4. Why Propose Alternative Development Patterns?
The causes of the development trend favoring large single
function compounds are easy to trace. Land use regulations, created a
century ago to protect residential property from noxious industry,
generally favor single purpose zoning. In addition, developers and
the financing institutions they depend upon tend to develop their
business expertise in one functional area (i.e., housing, office parks
or shopping centers) and for the most part do not welcome the
complexities of mixed-use town development.
New regulatory measures have been enacted in towns in the region
to reduce the impact of these large developments on their environment
and infrastructure. But there has been little effort to change the
underlying zoning to encourage new developments to enhance the
existing community or to become a complete community in their own
right.
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As shown through the analyses and reports produced for the
emerging New Jersey State Development and Redevelopment Plan, and the
1987 MSM REGIONAL FORUM, such large, single function development
patterns consume enormous amounts of land, tax the transportation
infrastructure through their auto dependence, force up the cost of
housing, and degrade the environment and community character of the
region. Both planning documents call for a regional approach to
growth management and the creation of regional mixed-use centers as an
alternative development pattern.
The professional planning community is now promoting many of
these changes under the banner of "neo-traditional" planning
techniques. However, the federal Clean Air Act, with its powerful
mandate to reduce vehicle miles traveled (VMT), as well as auto
emissions, will force New Jersey regulators - under threat of losing
major federal funding - to use land use plans to help achieve these
targets. Demand management techniques, largely an effort to mitigate
the damage that auto-dependent land use patterns have created, will
not be successful enough on their own. The underlying land use
patterns must change as well.
B. Defining Alternative Development Patterns: The Construct Approach
1. Three Basic Construct Types
In this study, the construct approach was adopted to show that,
as an alternative to current land use trends, reasonable models of
higher density, mixed-use centers could fit within the geographical
and socioeconomic settings of the suburban MSM region. The constructs
take into account that there is a continuing demand for residential
and employment opportunities within the region, albeit at a slower
pace than in the 1980's. They also take into account some basic
transportation assumptions of the region, namely:
- The automobile will remain the dominant mode of travel for
employees and residents.
- Because of the proximity of the NJ Transit/AMTRAK rail line and
the relative proximity of New York City and Philadelphia,
employees and residents have some receptivity to transit
services.
- There is a basic familiarity with ridesharing, particularly for
commuting purposes.
- Polls have demonstrated that people like the pedestrian
amenities and opportunities that "small town' aesthetics offer.
These attributes were accepted by both the steering committee and
the peer review panel.
Three basic construct types were identified to represent three
transportation environments: the Transit Construct, the Short Drive
Construct, and the Walking Construct. These are further defined
below.
a. The Transit Construct
This construct represents the largest, densest and most complex of
the three construct types. It is anchored between a transit hub
(e.g., a rail station or convenient bus route) and a major highway.
(See Figure 4.) Commercial and residential land uses are mixed to
provide a jobs/dwelling unit ratio of at least 2.18.
11
The Transit Construct shows a high density concentration of
employment and transportation services near a rail station, and a
second high density of employment and retail activity at the highway
connection point. The Main Street of the Transit Construct and its
access roads connect the two transportation nodes and create a
pedestrian and transit focused spine. Transit facilities may include
shuttles along Main Street and regional and local collector bus
service providing service from the residential areas to the employment
facilities and the Transit Hub.
The focal point of the Transit Construct is the Town Square, which
is near the construct's geographic center and houses its primary local
institutions and civic facilities.
As found in the other two constructs, the Transit Construct, as do
the other two constructs, has strong public and private sector demand
management policies in place. It has restricted, preferential parking
and a transportation coordinator on site.
b. The Short Drive Construct
The Short Drive Construct has a structure similar to the Transit
Construct, but is somewhat less dense and lacks direct access to a
transit hub as a second transportation anchor (see Figure 5). Main
Street still acts as an important spine, but now it is shorter and
only connects the Regional Shopping and Market Square area of the Town
Center.
Since the Short Drive Construct is not well served by convenient
public transit, the denser residential areas are clustered near enough
to the center to permit access on foot. The less dense parts are
spread somewhat further and require a short drive to shopping and
employment opportunities either by private auto or shuttle buses. The
jobs/housing ratio here is 3.39.
In comparison to an ordinary office park, a reduction in trips in
the Short Drive Construct is produced by having more housing and
retail services near the employment site and by the use of strong
demand management policies. There is restricted and preferential
parking, and a transportation coordinator on site.
c. The Walking Construct
The Walking Construct is basically a higher density residential
village, with minimal employment opportunities, located off the main-
highway network. It is sufficiently compact to permit access on foot
to the center from most of the residential areas (see Figure 6). The
cluster pattern of the neighborhoods facilitates vanpools and
ridesharing to regional employment centers.
The Town Square is the focus of this more limited mixed-use area
and is almost completely locally oriented. If the Primary Connecting
Road is not overwhelmed by high speed traffic and can bring some
additional clientele from surrounding communities, the Town Square may
develop into a kind of Main Street. Many of the existing village
centers could evolve into this pattern. While there is some
commercial employment within the walking construct, its jobs/housing
ratio is only 0.14.
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2. Urban Design Components of the Three Constructs
The Transit Construct, the Short Drive Construct and the Walking
Construct show basic differences of size, scale, organization, focus
and pattern. On the other hand, all three represent a major departure
from prevailing patterns of development and are made up of similar
components of successful urban design for viable towns with a full
complement of community functions. These components are in most ways
traditional prototypes drawn from successful cities and towns of the
past, updated to accommodate today's functional requirements.
The visual imagery of these components can vary. The key to
success is that the basic density and functional layout requirements
needed for a sound transportation and land use plan are accompanied by
massing, zoning, and street environment concepts that support a
pedestrian environment and the community life of the town. Thus, we
illustrate general scale, proximity and massing relationships on the
plan and cross section diagrams (Figures 7-10), but avoid advocating
particular architectural vocabularies.
The following are some of the key design components. Refer to the
plan and cross section diagrams for their illustration.
- Streets: To function properly, streets must be committed to
full-time civic use. By contrast, malls, drives, cul-de-sacs,
and other contemporary devices tend to serve single, semi-
private purposes and restrict the public life of a town. The
best streets allow for some mix of livable and interesting uses,
such as cars, pedestrians, service vehicles, bicycles, baby
carriages, etc.
The use of the street and adjacent relationships of private
properties should be regulated by public code. Grids of streets
serve multiple functions and civic purposes by creating an open-
ended, continuously connected system with enough redundancy to
be adaptable and flexible.
The actual shape of the open grid can vary with topography,
density, and design intent, but its basic integrity should be
consistently maintained. Older, traditional towns have many
examples of successful streets.
- Main Streets: The traditional center of American cities and
towns is "Main Street," characterized by a mix of uses and
transportation modes and a high level of pedestrian activity and
interaction. Dense, mid-rise buildings (3-5 story) with retail
uses on the ground floor, and small offices, workshops and
apartments on the upper floors usually create the right mix.
The scale and density of the "Main Street" at Forrestal
Village would be quite appropriate for the constructs. However,
unlike the one at Forrestal Village, Main Street needs to be
connected to and become the focal point of the street grid in
order to attract pedestrians from surrounding neighborhoods.
Vehicles should be allowed on Main Streets, but their volume and
speed controlled to maintain a pedestrian orientation.
Main Street should connect to the principal squares of the
town and should be within walking distance from most residential
blocks. In the Transit Construct, shuttle transit should run
along the length of Main Street.
- Squares: Squares are special spaces in the street network where
functional, civic, recreational, and ceremonial activities of
the city or town can be focused. In the larger constructs, the
functions can be split -- i.e., one square devoted primarily to
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institutions, another to markets, a third to transportation -
but these definitely need to be in close relationship to each
other. Pedestrian emphasis and connection among the squares is
essential.
- Major Connector and Service Roads: The size and density of
settlements considered for the constructs creates a great deal
of auto traffic bound for highly concentrated employment, retail
and transit centers. For this reason, roads should be
designated in the grid to handle primary traffic and give access
to the main parking garage concentrations., In the two larger
constructs, these connector roads should be separate from Main
Street and not have major pedestrian or retail concentrations at
street level.
Generally, at the scale of these settlements, traffic signal
timing and other management techniques, rather than grade
separation, should be used to insure adequate flow along these
roads. The plan diagrams and Town Center cross section
illustrate the relationship of these roads to the other elements
of the grid, land uses, and parking areas.
- Parking Design: The large amount of area required for parking in
these towns where employment and retail are concentrated
(roughly a 1:1 ration of space devoted to parking and all other
uses), necessitates a very careful design approach to parking.
It is assumed for the constructs that in order to create the
density and continuity required for mixed-use centers, most of
the parking for employment and Main Street related activity will
be in multi-level structures. This will be an economic burden
for the developers, but in recent developments--such as
Forrestal Village, Carnegie Center in West Windsor and the
proposed Metroplex office park in South Brunswick--have set the
precedent by including multi-level parking garages.
The key design principle is to make these parking structures
easily accessible from the main connector and service road, but
to prevent them from dominating the streetscape of Main Street,
the Squares, or the residential streets. Ideally, garages
should be located at the center of commercial blocks, faced with
stores at the ground level and other uses above.
Parking for the residential areas should generally be
absorbed in driveways, garages, or carports on a small scale
directly adjacent to the units, as shown in the site diagrams
and Town Center cross section. But controlled street parking
should not be prohibited.
- Residential Neighborhoods and Streets: Neighborhoods need a
greater level of privacy and protection from heavy traffic than
other, more public uses. Residential streets can be designed to
enhance, but not dominate the neighborhood, and still remain
connected to the public street grid that ties the town or city
together.
Traffic Management should insure that these streets carry
primarily local traffic at low speeds. Front doors and parking
and front doors should generally occur at or near the street to
keep an active community character. Density, proposed in the 10
to 15 dwelling units per acre range (on average), should be
highest near Main Street and diminish toward the edges. These
densities are equivalent to traditional single-family
neighborhoods, and recent townhouse and apartment complexes in
the region.
21
- Institutions: Government buildings, schools, colleges, day care
centers, and public recreation facilities need to be provided in
prominent public locations, easily accessible on foot and by all
other modes of transport. Schools and recreation facilities
need to be directly connected to the city's open space system.
- Open Space Networks: Streets, provided with sidewalks that are
scaled to the amount of pedestrian activity, are the most used
part of the public open space network, and should be landscaped
with trees and enhanced with other planting on the adjacent
private properties.
Walkways other than sidewalks are needed primarily in the
densest commercial areas, where arcades and through block
passages are a welcome and valuable enrichment and in the
undeveloped periphery, where public walkways should give access
to natural attractions.
3. Key Characteristics of the Constructs
Specific characteristics of the three constructs were developed by
the project team and were reviewed and revised by the initial peer
group and the steering committee. The density and size of the Transit
Construct were designed to maximize the use of transit and paratransit
services while maintaining the suburban fabric of the development.
However, for the Short Drive and Walking Constructs, the
characteristics were based on standards put forth for "regional
centers" and "towns and neighborhoods" as defined by MSM's REGIONAL
FORUM in 1985-87 and followed by the Preliminary State Development and
Redevelopment Plan.
The FORUM convened regional public and private sector leaders, as
well as interested citizens, to address ways to better manage growth
in the region. This consensus-building effort developed a set of
recommendations for efficiently concentrating growth into mixed-use
centers. (See An Action Agenda for Managing Growth, Final Report of
the MSM Regional Forum, 1987.)
Table 1 shows the key characteristics used in the Land
Use/Transportation Study for all three constructs. These are
presented as minimum thresholds rather than absolute dimensions of the
constructs. (The estimates in Table 1 were used for Scenario 1.
Scenario 2's estimates were larger in order to accommodate more
suburban growth.) A summary of major points follows:
a. Population
The number of residents ranges from 12,000 in the Transit Construct
to 6,700 in the Short Drive Construct, to 4,500 in the Walking
Construct. Residential density ranges from 15 dwelling units per net
residential acre (average) for the Transit Construct, to 10 dwelling
units per net residential acre (average) for both the Short Drive
Construct and the Walking Construct.
b. Employment
Employment opportunities are significant in the Transit Construct
(13,100 jobs) and the Short Drive Construct (9,500 jobs), but
negligible for the Walking Construct (230 jobs). The commercial land
use floor area ratio is 2.0 in the Transit Construct, 1.1 in the Short
Drive Construct and 0.4 in the Walking Construct.
Both the Transit Construct and the Short Drive Construct have
regional retail anchors, while the retail component of the Walking
Construct is assumed to be a neighborhood center.
22
Table 1
MSM LAND USE CONSTRUCT COMPARISON
Transit Short Drive Walking
Characteristic Construct Construct Construct
"TC" "SD" "W"
COMMERCIAL COMPONENTS:
Comm. Floor Area(SF) 4,000,000 3,000,000 10,000
Comm. Employment 12,000 9,000 30
Commercial FAR 2.0 1.1 0.4
Comm.Net Acres 45.9 62.6 0.6
RETAIL COMPONENTS:
Retail Floor Area(SF) 550,000 250,000 50,000
Retail Employment 1,100 500 200
Retail FAR 1.00 0.40 0.23
Retail Net Acres 12.6 14.3 5.0
NON-RESIDENTIAL TOTALS:
Total Employment 13,100 9,500 230
Total Net Non-Res. Acres 58.5 77.0 5.6
RESIDENTIAL COMPONENTS:
Population 12,000 6,700 4,500
People per D.U. 2.0 2.4 2.8
Dwelling Units 6,000 2,800 1,600
D. U. per Net Res. Acre 15 10 10
Net Residential Acres 400.0 280.0 160.0
TOTAL CONSTRUCT FACTORS:
Jobs per D.U. 2.18 3.39 0.14
Workers per D.U. 1.0 1.5 1.5
RESERVE AREAS:
Open Space 15% 15% 15%
Roads/Utilities 25% 28% 28%
Public Buildings, etc. 10% 10% 10%
GROSS DIMENSIONS:
Area in Acres 917 759 352
Area in Sq. Mi. 1.43 1.19 0.55
Radius if Circular (FT.) 3,566 3,245 2,210
23
c. Jobs to Dwelling Units Ratio
This ratio reflects the mixed-use elements of the Transit Construct
(2.18) and the Short Drive Construct (3.39), while indicating that the
Walking Construct (0.14) is simply a residential center.
d. Gross Dimensions
In order to accentuate the potential for walking trips among land
uses, an attempt was made to concentrate each construct into a
relatively compact area. As a result, the Transit Construct
represents an area of over 900 acres, the Short Drive Construct
represents an area of over 750 acres, and the Walking Construct
represents an area of over 350 acres. This includes not only the
residential, commercial and retail land uses, but open space, roads,
utilities and public buildings as well.
C. The Role of Constructs in Reducing Vehicle Traffic: Local Level
Analysis
Each of the three constructs was designed to reflect a "package" of
land use mix, density, transportation, and demand management
attributes which in combination reduce automobile usage. In this step
of the study, the effects of each construct on reducing auto travel
were quantified by the type of development in each construct for peak
hours, off-peak hours and daily trips. The analysis was designed both
to identify the specific traffic reduction benefits of constructs at
the local level, and to show the overall effects on the regional
network. The regional analysis discussed in Chapters III & IV was
conducted only for the more general measure of daily travel.
1. Assumptions
The analysis was based on a number of assumptions about the trip
types considered and their trip rates, and the effects of the
different constructs on tripmaking, as follows:
- As the target of the study was the reduction of automobile
trips, the trip generation dealt with vehicle trips. The effect
of changes in modal shifts to transit, carpools or walking was
thus expressed as an estimated change in vehicle trips.
- The product of the trip generation was vehicle trips with an
origin or destination external to the construct, as intra-
construct trips do not impact the area roadways to any
significant extent. Traffic zones in the model were not smaller
than a construct.
- Tripmaking generated by each construct was accounted for in
three categories:
- commercial (represented mainly by office rates),
- retail; and
- residential uses.
- The time periods considered were:
- AM Peak Hour
- PM Peak Hour
- Off-Peak periods
- Average Weekday (ADT)
24
Travel behavior description and analyses for the constructs
required inclusion of all such periods. For determination of off-peak
period trip rates, twice the sum of the AM and PM peak hour rates (to
determine the peak period) was subtracted from the ADT rate.
2. Methodology
Construct-level analysis was based on the premise that the
constructs chosen reduce (external) vehicle trips. These vehicle trip
reduction factors were developed for each construct, trip type and
time period compared to basic trip rates. Comparison among the
constructs is possible by looking at the differences in construct-to-
trend ratios. (See Appendix A.)
3. Construct Land Use and Transportation Relationships
A review of the literature in land use/transportation
relationships, transportation demand management and of case, studies
of suburban activity centers indicated that the general effects in
terms of land use and travel relationships can be summarized in five
areas, as follows:
a. Internal Vehicle Trips increased by:
- Greater employment opportunities for residents. (Jobs/Housing
ratio more balanced within zone.)
- More retail/services for residents or employees. (Mixed-use
enhanced.)
b. Internal Walking Trips increased by:
- Combination of jobs, retail/services and residences in close
proximity with one another. (Density and mixed-used
enhanced.)
- Pedestrian oriented site planning and design.
c. Internal Transit Trips increased by:
- Presence of local transit service, i.e., shuttle/feeder
buses. (Density enhanced.)
- Greater variety of trip purposes served. (Mixed-use
enhanced.)
- Transit oriented site planning and design.
d. External Trip Shift to Transit increased by:
- Good transit available to serve remote residents working in
construct and construct residents working in remote job
centers. (Density and mixed-use enhanced.)
- Transit incentives, such as transit pass subsidy by
employers, etc. (Demand management enhanced.)
25
e. External Trip Shift to Carpools increased by:
- Greater carpool matching potential i.e., convenience of
association at both ends of trip. (Density and mixed-use
enhanced.)
- Carpooling incentive through parking management and pricing
at destination. (Demand management enhanced.)
Of course, each one of the features listed above has a varying
influence on the reduction of vehicle trip making, and, in most cases,
the features' interaction with each other complicate estimating. In
addition, similar end results can be caused by the varying interaction
of different factors in different constructs.
4. Determination of Vehicle Trip Reduction Factors
Once basic land use and transit relationships were established,
specific vehicle trip reduction factors for each construct were
determined through the steps below. The project team developed the
factors and had them reviewed by the peer group. All land use based
reduction factors were applied to Institute of Transportation
Engineers average vehicle trip rates for the AM peak hour, PM peak
hour, off-peak period and the average daffy traffic (ADT) conditions,
while the values for the regional analysis were limited to daily (ADT)
vehicle trips.
a. The Factors Influencing Trip Reduction
The vehicle trip reductions from the constructs result from a
combination of factors:
- overall office/retail/housing mix;
- jobs/housing ratio;
- total employment;
- design integration;
- proximity to rail transit;
- presence of radial bus service;
- presence of internal bus service;
- constrained, and in the case of the Transit Construct, priced
parking supply for commercial uses; and increased residential
density.
b. How the Factors Operate on Travel Behavior
As discussed above, these factors in various combinations can bring
about varying degrees of reduction of single occupant vehicles, due
to:
- internalization of vehicle trips, whether by vehicle, transit,
or walking; and/or
- reduction of external vehicle trips by shifts to transit or
rideshare modes.
c. Using NCHRP #323
In looking for case study data to use in measuring the vehicle trip
reduction effects of these characteristics, one of the best sources,
containing the largest, most recent and most consistent data set is
NCHRP #323, Travel Characteristics at Large-Scale Suburban Activity
26
Centers (October, 1989) by Kevin Hooper1. As shown in his report and
in other studies such as Cervero's2, existing "suburban activity
centers" or "suburban employment centers" typically exhibit some of
the above characteristics, but not all. Existing centers exhibit some
land use mixing (particularly office/retail), but generally, with the
possible exception of Bellevue, Washington, do not have the level of
residential development, the parking restraints, the clustering, rail
service, internal transit service, or pedestrian amenities included in
our constructs.
The literature indicates that many of the suburban activity centers
are actually more like "trend" development than the constructs.
Individual cases where higher transit use or walking rates have been
achieved are those, like Bellevue, where there is transit, more
housing units, better integrated design, or pedestrian walkways, etc.
Beyond the NCHRP #323 report, other case studies are useful insofar
as they measure effects of transportation demand management measures,
individual land use or transit service characteristics. Those others
do not consider the land use mixing.
d. Basic Trip Reduction
Thus, a decision was made to use the average values from NCHRP #323
as a base indicator of trip reductions which can be achieved through a
limited amount of mixing land uses and increasing density in suburban
activity centers which would otherwise be dispersed in a "trend"
(sprawl) pattern. The case study data provided the benchmark values
and empirical evidence which were used as the starting point for the
regional testing.
It should be noted that the base trip reductions are fairly
substantial in themselves. Their impact, regionally, could be fairly
significant without full construct development.
e. Enhanced Trip Reduction Factors in Constructs
Then, for each land use under each construct, additional case
studies and the experience of observed behavior were used to estimate
added reductions which could be attributed to the particular features
assumed for our constructs. Some of these reductions are tied to the
Hooper data for Bellevue and other case study data of developments
which are most like our constructs.
Others are estimates, based on work/non-work trip percentages,
ratios of employment to housing, etc. For some trip types there are
no further trip reductions beyond those indicated in the Hooper cases.
(As noted in Appendix A.)
The exception is the walking construct, which is not really a
"suburban activity center" as currently defined, and for which there
is the least case study data. The most comparable data, if available,
would probably be from new towns such as Reston or the new "neo-
traditional suburbs." In this case, the project team reached a
decision that the base
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1. Hooper, Kevin G. Travel Characteristics at Large-Scale Suburban
Activity Centers, National Cooperative Highway Research Program Report
323, (October, 1989).
2. Cervero, Dr. Robert. America's Suburban Centers: A Study of the
Land Use/Transportation Link, Prepared for Office of Policy and
Budget, Urban Mass Transportation Administration, Report No. DOT-T-88-
14, Washington D.C. (January, 1988).
27
case trip type values could not be achieved in all cases, since the
walking construct had the least similarity to the mixed-use centers
studied, notably its lack of employment opportunities. Therefore, in
the case of the walking construct, smaller base reductions were made
for some trip types through negative adjustments.
f. Factoring to Avoid Double Counting
The resulting trip reductions were then combined for each construct
through factoring. In this way the values for the individual
components were combined as the product of sub-factors for each
percentage. This was done to avoid double counting. For example,
transit users produced by construct conditions are not available for
carpools, and vice versa. If individual trip reductions of 15 percent
and 10 percent might be estimated for transit mode shift and
carpooling, respectively, the reduction factor would be 0.765 (0.85 x
0.90), implying a lesser reduction of 1 - 0.765 = 0.235 or 23.5
percent.
Table 2 on page 30 summarizes the total vehicle trip reductions by
construct. The table shows that compared to the trend vehicle trip
generation rate, the number of vehicle trips generated and attracted
to that construct will be reduced by that factor. (See Section 5 on
the following page, for example. Detailed tables showing calculations
of vehicle trip reductions for each construct are included in Appendix
D.)
It is difficult to substantiate every factor as applied to every
trip type. However, it is possible to see how each construct compares
to the current suburban activity centers for each type of trip.
Looking at the literature, the values chosen for use in the analysis
are within ranges which have been measured in other case studies such
as those presented in the ITE 1987 Trip Generation Manual1 and the
Stover and Koepke text Transportation and Land Development.2
Similarly, the February, 1990 FHWA report, Evaluation of Travel
Demand Management Measures to Relieve Congestion3, states that by
instituting programs of Transportation Demand Management (TDM)
measures, "trip reductions in the range of 20% to 40% can be the norm,
rather than the exception." Although our study purposely does not
attempt to isolate TDM program effects from land use factors, TDM
programs such as constrained and priced parking, TMA activity,
rideshare incentives, and staggered work hours are considered part of
each construct "package" along with the land use mix, density, and
design features which are the focus of this analysis.
Land use based vehicle trip reduction factors were later converted
to Home Based-Work, Home Based-Other, and Non-Home Based categories in
the AM peak hour, as required by the network model used in the
TransCAD package. Figure 11 shows the travel reduction factor for
each construct type for the four key time periods, compared to the
same land use developed under trend conditions. The model was run for
1988 conditions, the 2010 "trend" scenario, and two construct
scenarios (ADI), as explained in Chapter IV.
--------------------
1. Institute of Transportation Engineers. Trip Generation, 4th
Edition (1987) pp.17-21.
2. Stover, Virgil G. and Frank J. Koepke, Transportation and Land
Development, Institute of Transportation Engineers, Englewood Cliffs,
New Jersey (1988) pp. 47-48.
3. Kuzmyak, J. Richard, Eric N. Schreffler, and Harold Katz, et al.
Evaluation of Travel Demand Management (TDM) Measures to Relieve
Congestion, Report No. FHWA-SA-90-005, prepared for Federal Highway
Administration, Washington, D.C. (February, 1990), p. 28.
28
5. Producing a Vehicle Trip Reduction Factor: An Example
An example of how this method is applied, related to office trips,
follows. The numbers correspond to those shown in Table 2 on the next
page.
- For office use in the AM peak hour, NCHRP #323 shows that for
"smaller centers," (those most similar in size to the
constructs), an average of 10 percent of employees make a stop
within the activity center. Mode shift data from NCHRP for the
non-Bellevue suburban centers1 show that, on average, 1 percent
use transit, walk or bike, and 7 percent carpool. These values
were put into the matrix as base case study values. It was
assumed that these reductions would be achieved as a minimum
vehicle trip decrease from the trend values in any of the
constructs. Result: 0.90 x 0.99 x 0.93 = 0.83 net vehicle trip
reduction factor.
- Then, for the transit construct an additional 2 percent internal
trip reduction was estimated, due to the internal transit system
and improved walking conditions. An additional 12 percent
transit use was estimated, based on Bellevue's 10 percent
transit mode share (with radial bus system), plus an estimated 2
percent reduction due to the rail access. Reductions due to
ridesharing were not increased over the case study value.
Result: 0.83 (from base case, above) x 0.98 x 0.88 = .71 net
vehicle trip reduction factor.
- For the short drive construct, reductions due to increased
internal walking were increased by 1 percent, and carpooling was
increased 8 percent over the base values, based on Cervero's
findings of 15 percent carpool rates for large and medium mixed
use centers. Result: 0.83 (from base case, above) x .99 x .92 =
.75 net vehicle trip reduction factor.
- For the walking construct, office trips represent a much smaller
proportion of total travel, but, due to their location, they
attract a large proportion of employees and visitors from within
the construct. Thus, the 10 percent internal trip reduction
from the base case was deemed valid for office uses in this
construct. However, no external transit use or carpooling
increases were predicted for the walking construct, due to the
absence of new regional services and the low proportion of use
in commercial space, which would not justify adding local bus
service. Thus, these values were listed as negative values
(translated into factors greater than one) in the table.
Result: 0.83 x 1.01 x 1.07 = 0.90 net vehicle trip reduction
factor.
Vehicle trip reduction factors were then applied to vehicle trip
generation numbers that the basic model produces. By this method, the
special vehicle trip reduction characteristics of constructs as
opposed to land uses in the region were taken into account.
--------------------
1. For the transit use value, Bellevue is excluded from the base case
value due to its atypical, higher level of transit service which would
raise the base value too high to be used in all cases.
29
Table 2
Summary of Vehicle Trip Reduction Factors
Trip Type Land Use Construct Factor
Short
Trend Transit Drive Walking
COMMERCIAL:
Average Daily 1.00 0.69 0.73 0.81
AM Peak Hour 1.00 0.71 0.75 0.90
PM Peak Hour 1.00 0.71 0.75 0.90
Off-Peak Periods 1.00 0.67 0.71 0.75
RETAIL/RESTAURANT:
Average Daily 1.00 0.73 0.76 0.81
AM Peak Hour 1.00 0.83 0.85 0.86
PM Peak Hour 1.00 0.83 0.85 0.86
Off-Peak Periods 1.00 0.67 0.70 0.77
RESIDENTIAL:
Average Daily 1.00 0.73 0.78 0.82
AM Peak Hour 1.00 0.59 0.69 0.77
PM Peak Hour 1.00 0.59 0.69 0.77
Off-Peak Periods 1.00 0.82 0.84 0.86
Note: Compared to the development pattern expected to occur in the MSM
region by the year 2010 (if Trend conditions continue),
constructs would produce fewer vehicle trips on the regional
highway network. As this chart shows, if the Trend represents
the expected level of vehicle tripmaking, then the constructs
produce daily trip levels between 0.59 and 0.90 of what would be
expected to occur, depending upon trip types and construct
types.
30
Figure 11
Ratio of Construct Total Trips Compared
to Some Construct with Trend Rate
Click HERE for Graphic
31
CHAPTER III:
DEVELOPING THE REGIONAL TRANSPORTATION MODEL
A. Basic Components of the Regional Transportation Model
In MSM's Land Use/Transportation Project, a regional transportation
model was developed to provide a platform for evaluating the traffic
impacts of alternative land use forms in the MSM study area. In
particular, it was designed as a means for testing the hypothesis that
placing future development in constructs would have a positive impact
on traffic in central New Jersey.
The modeling procedure involved three methodologies of particular
interest:
- Building the MSM network with reliance on previous efforts;
- Using the GIS-based TransCAD package; and
- Accounting for the traffic reduction effects of construct
development in the regional model.
These are briefly described below and more extensively in the
remainder of this chapter. More detailed descriptions and tables are
included in Appendix B.
1. Building the MSM Network with Reliance on Previous Efforts
The MSM area presented a particularly intriguing modeling
challenge. The region lies at the edge of two regional planning
agency boundaries: Philadelphia to the south and New York
City/Northern New Jersey to the north. Although parts of the three
counties were included in previous transportation modeling projects,
there was no uniform network and no calibrated model covering the four
standard transportation planning steps (trip generation, trip
distribution, modal choice, and network assignment) for all three
counties. Thus, the project team was faced with piecing together data
and information from other studies and regional planning efforts.
2. Using the GIS-Based TransCAD Package
The demands placed on the regional transportation model were
similar for this study to those for any regional study, but with the
added desire to control and manipulate land use and demographic data
more easily. Because of this goal, enhanced capabilities compared to
typical transportation packages were needed.
The TransCAD package, which combines the normal battery of
transportation models with a Geographic Information System (GIS),
provides these capabilities and thus was used in this study.
32
3. Accounting for Traffic Reduction Effects of Construct
Development in the Regional Model Another challenge for this
project was the fact that the typical four-step travel demand
models used throughout the nation generally are not capable of
reflecting land use variables related to density/cluster
development attributes or accessibility by walking and other
non-motorized means. The regional transportation model used in
this study was geared toward a more typical urban/suburban
setting, and it dealt exclusively with vehicle trips.
As a result, a two-step process for defining and accounting for the
traffic reduction features of the constructs was undertaken, as
illustrated in Figure 12. The first step, distinct from the TransCAD
package and described in Chapter II, was undertaken by the project
team with input from the peer review panel and the steering committee.
As discussed, and because the regional models dealt only with
vehicle trips, this process first analyzed the specific effects of
each construct's land use density, mix, and design and its transit
service availability on mode choice, trip length, and auto occupancy
for each individual construct. This provided the detailed zone-level
analysis of specific construct impacts for various time periods.
Then, to enable input into the regional model, these effects were
translated into vehicle "trip reduction factors," which could be input
directly into the regional model by traffic zone at the vehicle trip
generation stage to modify construct tripmaking relative to "trend.'
In regional aggregation, this provided the means to compare each
construct scenario to the "trend" scenario development trips.
It should be noted that the basic vehicle trip reduction factors
used to adjust trend rates for each construct were initially
formulated on the basis of ITE Trip Generation rates on a land use
basis, as described in Chapter II. For application to the trip
generation categories of the regional model, it was necessary to
convert the basic factors to apply to the model categories of separate
productions and attractions by varying purpose definitions. This will
be discussed further in Section D below.
B. Building the MSM Network with Reliance on Previous Efforts
1. Building the 1988 Network
To conduct the travel demand portion of this study, it was
necessary to assemble a data base reflecting the highway and
demographic conditions of the study area. The highway portion of the
data base was used to simulate traffic flows for a given year. In
this study, a calibration year of 1988 and a future year of 2010 were
used. The demographic data used as inputs to the traffic models were
also estimates for the years 1988 and 2010.
Data sources for the highway data base consisted of four networks
supplied by the New Jersey Department of Transportation (NJDOT) from
studies it had completed. The networks supplied were from the North
Jersey Regional Transportation Model Development Project and the Route
1, Route 130 and Route 571 studies. Three of the four networks
(Routes 1, 130 and 571) consisted of existing and future links,
although not representing the same years. The North Jersey network
supplied only the links for 1988 because the future network for that
study was still in development. These four networks were used because
they covered the majority of the MSM study area with the exception of
Hopewell
33
Figure 12: Chart of Study Process
Click HERE for Graphic
34
and a portion of Ewing Township. No individual network provided
complete coverage of the study area, so the four networks were
"stitched" together. (NOTE: Although Trenton and New Brunswick were
covered, the network was not fine-grained enough to accurately
describe urban travel behavior. Because of time and financial
constraints, refinements of the cities' network and zone system were
not attempted in this study, and the results are therefore limited to
suburban analyses).
To simplify this process, all four networks were loaded over a
common base map in TransCAD. By doing this, the consultant team was
able to eliminate any portion of a given network that was covered by
another. By first establishing the Route 1 network as the base to
build from, the other three networks were reduced by deleting where
they overlapped the Route 1 network.
The link detail, zone size and coarseness of the Route 130 network
closely matched that of the Route 1 network, so it was retained and
the Route 571 network was dropped. In addition, although much of the
Route 130 network was dropped because of duplicate coverage with Route
1, its network was used to complete the eastern portion of Mercer
County and fill in areas of sparse coverage on the eastern fringe of
the Route 1 network.
The North Jersey network supplied coverage for the southern halves
of Somerset and Middlesex counties. This was the southern-most extent
of the North Jersey network and was stitched to the northern limits of
the Route 1 network. Each of the older networks had somewhat
different attribute conventions since the Route 1 study used UTPS, the
Route 130 study used a MINUTP network and the North Jersey network was
developed using Tranplan. For the MSM network, the consultant team
needed to transfer the number of lanes, initial speeds and per lane
capacity (facility; and type) from the parent network. This was done
by using the TransCAD package, which has superior capabilities for
defining link length and location with greater accuracy than the
parent systems.
The project team developed new networks and a zone system for
Hopewell and Ewing Townships. Speed and capacity classifications for
these new links were defined using the facility and area
classification table from the Route 1 Corridor Study Report.
2. Building the 2010 Network
The calibration network was used as a base from which the future
network, used in the Trend and Scenarios 1 and 2, was constructed.
Both the Route 1 and Route 130 Studies contained future networks. The
differences between the calibration and future networks of these two
studies represent the proposed projects in the MSM Region. Since the
completion of the Route 1 and Route 130 Studies and since the start of
this study, a number of highway projects assumed to be constructed are
either under further study or lack funding to implement. These
projects include Route 92 through Middlesex County and the widening of
Routes 27 and 130. Therefore, they were not included in this study.
Discussions with NJDOT revealed four highway facility changes to
the MSM calibration network that could be completed by 2010: 1)
extension of Route 29 from the Trenton Freeway to the I-195/295
Trenton Complex in western Washington Township, Trenton and Hamilton
Township; 2) extension of I-295 from the Trenton Complex into Bucks
County, Pennsylvania (this extension functions as an external
connector in the network); 3) the Hightstown Bypass; and 4) the
widening of the New Jersey Turnpike by two lanes from Cranbury Road to
State Highway 18.
35
These changes were incorporated into the existing (calibration)
1988 network to form the 2010 network used for this analysis. It
should be stressed, however, that these projects are not necessarily
included in NJDOT's committed capital programs.
3. Building Traffic Zones
The MSM region was divided into nearly 200 geographic zones, within
which population, employment and other relevant land use/demographic
data was stored. Trips originating from or destined to each zone link
up to the regional network from each zone centroid via a centroid
connector to the highway links. Zones were built as an amalgam of
census blocks, a process expedited by TransCAD's GIS capabilities.
There is some correspondence between the zones built for this effort
and those used in the other modeling efforts described earlier.
(Appendix B shows the zonal layout for the MSM region.)
Constructs for the year 2010 were assigned either to an existing
traffic zone or to a new zone created from segments of one or more
existing zones. Placing a construct in an existing zone(s) meant that
any existing development in the zone (as of 1988) would be absorbed in
and take on the behavior pattern of the construct development. This
implies that the existing development served as a foothold upon which
the construct was built. All but four of the constructs created in
this study were assumed to be developed in this so-called "piggyback"
fashion. In the four new zones, the travel behavior is characterized
by the construct factors, but the persons in the surrounding zones
with trend-type development would not change as a result of proximity
to the construct development.
4. External Trips
The model accommodates external trips. There are two types of such
trips: first, trips that pass through the MSM region without origins
or destinations in the area; and second, trips that either originate
from or are destined to the region, but with destinations or origins
outside the region. The Route 1 model had to be adjusted to account
specifically for the trip generation of zones that the original model
treated as external points, but which were now contained within the
larger MSM network.
C. Using the GIS-Based TransCAD Package
The GIS-based TransCAD package contains a gravity model and an
equilibrium traffic assignment model among its battery of procedures.
It also provides numerous procedures for processing land use data,
constructing/subdividing traffic zones, calculating the precise
location and adjustment of transportation links, and summarizing
traffic phenomena by geographic area. Thus, it provided most of the
models necessary for the current study, and allowed for direct entry
and manipulation of the land use database by the MSM professional
staff. A spreadsheet model calculated the daily person trip ends. A
complex combination of case study results provided the modal choice
(reduction) percentages for each type of construct. Constructs were
easily accommodated by creating new zones or altering zone boundaries.
36
D. Accounting for Traffic Reduction Effects of Construct Development
in the Regional Model
Because they were based on vehicle trip generation rates by
individual land use, the traffic reduction effects of the constructs
were taken into account in the Trip Generation step of the standard
four-step transportation modeling process. To be used in the model,
however, the rates had to be converted from land use based rates (i.e.
vehicle trips per 1,000 square feet of floor space) to rates which
could be applied to the different trip categories used in the model.
This procedure is discussed below.
This study used a simplified set of vehicle trip generation
equations in order to reduce the need for detailed zone level land use
forecasts. The relationships in the parent studies required estimates
of housing units by type (single family, low-rise multi-family, high-
rise), or household size and income. It should be noted that the
North Jersey study, which used income and household size, did not
forecast dwelling unit levels for any future year.
This study developed a simplified set of vehicle trip generation
rates from the Route 1 Study rates, as shown in Appendix C. Where land
uses combined (e.g., single family and multi-family dwelling units),
the new rates were calculated as the weighted averages of the rates
from the parent study. Thus, they contained an implicit assumption
that the relative mix of dwelling types would remain the same in the
future for the basic trip generation equations. In a similar fashion,
new factors for trip attractions were weighted functions of various
employment categories which have been aggregated into retail and non-
retail categories.
The trip generation formulas used generated vehicle trips for three
basic trip types:
- Home-based-work trips, meaning trips made from home to work or
work to home;
- Home-based-other trips, meaning trips made to or from home, to
or from another, non-work destination; and
- Non-home-based trips, meaning a trip not made either to or from
home.
The formulas generated these vehicle trips for four different land
use types (reduced from the 16 land use types used in the Route 1
Study) namely:
- one residential type, combining various density types;
- two employment types, one being retail and the other non-retail,
which includes office, industrial, hospital, etc.; and
- one for university students.
All vehicle trips to (i.e., trip attractions) and from (i.e., trip
productions) zones were generated. A daily vehicle trip rate
represents the sum of attraction and productions for three trip types
and four land use types.
37
The vehicle trip generation formulas developed were applied to all
scenarios studied. The trip modification effects of the special land
use constructs were incorporated by applying construct trip reduction
factors (ITE/land use derived) as described in Chapter II, converted
to the model trip categories described on the previous page, and
applied to traffic zones where constructs are located.
The factor conversion or adaptation was done by analogy or
combination. Among the assumptions made were those that peak hour
travel, particularly AM, is home-based and work oriented, and that
off-peak non-retail commercial trips are dominantly non-home-based.
For example, the factor for residential AM peak hour trips is
appropriate for home-based-work productions, as virtually all of such
trips leave home and are destined principally to work. Similarly, the
off-peak commercial (non-retail) trip factor is appropriate for
application to non-home-based productions or attractions, as such
trips are unlikely to be going to or from home.
Once the vehicle trip reduction factors were converted to the model
categories, they were input into the model to reduce average daily
vehicle trips going to or from each construct zone in each of the two
scenarios analyzed. The results of the trend analysis, and the
analyses of the two alternative construct development scenarios are
discussed in the following chapters.
38
CHAPTER IV:
FORECASTING DEVELOPMENT SCENARIOS
A key element in testing the effectiveness of constructs of higher
density, mixed-use centers is to develop a forecast of future land use
patterns in the MSM region. In fact, multiple forecasts must be
developed: one representing the best estimate of current land use
development patterns without any shift to construct-type development;
and one or more forecasts representing the presence of construct
centers in the MSM region. A 2010 forecast year was used,
representing the latest year in which reasonable estimates of
regionwide development can be projected and the earliest year in which
to expect constructs to become a significant presence in the region.
Prior to developing these forecasts, however, it is important to
build a consistent set of baseline conditions, using the most recent
estimate of current land use and demographic characteristics in the
region. The year 1988 was designated as the latest year in which
existing conditions can be determined with any reasonable accuracy.
A. Developing 1988 Baseline Conditions
MSM staff developed 1988 conditions for the following key indices:
- Total number of households;
- Total retail employment;
- Total non-retail employment; and
- Total university student population.
The 1988 estimates were based on 1980 census data, more recent
estimates from the various municipalities in the region, and knowledge
of recent site specific developments from MSM's annual Current
Development Survey (MSM Regional Data Book). The 1988 levels were
estimated for each of the nearly 200 traffic zones. Table 3 shows the
various estimates aggregated at the municipal level.
B. Year 2010 Trend Conditions
The total growth increment from 1988 to the year 2010 for the MSM
region was based on county projections prepared for New Jersey's
Cross-Acceptance Process. This process required counties to help
develop the New Jersey State Development and Redevelopment Plan, by
soliciting input from municipal officials, interest groups and
community leaders. The expected growth levels in the MSM region for
the year 2010 as published in the 1988 Preliminary Plan are:
39
Table 3
1988 Baseline Conditions for MSM Region Communities
Municipality Non-Retail Employment Retail Employment Households
East Windsor 7,615 848 8,666
Ewing 26,152 2,508 12,541
Hamilton 22,302 5,623 31,336
Hightstown 2,055 800 1,818
Hopewell Township & Borough 3,299 168 4,673
Lawrence 14,684 6,617 8,616
Pennington 1,596 40 872
Princeton Township & Borough 20,615 1,647 8,804
Trenton 51,442 3,405 33,952
Washington 1,601 500 2,250
West Windsor 11,112 1,050 4,436
Mercer County 162,473 23,206 117,964
Franklin 21,855 2,087 13,502
Hillsborough 3,309 1,071 9,165
Manville 996 283 3,868
Millstone 35 19 180
Montgomery & Rocky Hill 7,385 595 3,290
South Bound Brook 426 69 1,502
Somerset County (part) 34,006 4,124 31,507
Cranbury 6,653 50 913
East Brunswick 17,315 8,004 13,555
Helmetta 154 11 439
Jamesburg 1,649 433 1,688
Milltown 2,415 242 2,412
Monroe 1,946 0 8,640
New Brunswick 32,395 2,857 12,682
North Brunswick 13,606 2,169 10,730
Plainsboro 5,847 1,152 6,833
South Brunswick 11,906 780 8,341
South River 1,814 423 4,823
Spotswood 1,720 454 2,904
Middlesex County (part) 97,420 16,575 73,960
MSM Region Total 293,899 43,905 223,431
40
- A growth of 182,581 new jobs, of which 14,292 are expected to be
retail jobs and 168,287 are expected to be non-retail jobs; and
- A growth of 187,905 new residents, or 92,016 new households.
Once again, year 2010 estimates at the zonal level are based on
projections of municipalities, knowledge of "pipeline" projects and
judgment of likely growth areas. Table 4 shows the various estimates
for the year 2010 aggregated at the municipality level.
C. Alternative Development Scenarios
The basis for alternatives to the expected trend development was
the substitution of construct centers for typical suburban land use
development. Chapter II introduced the three construct types: the
Transit Construct, the Short Drive Construct, and the Walking
Construct. All three are projected to be utilized in the MSM region
under alternative scenarios. In fact, this study assumes in its
alternative growth scenarios that all suburban growth will take the
form of constructs.
A major undertaking was to assign the appropriate number of
constructs to the region in particular geographic locations. The
purpose of this effort should be carefully understood: Placing
constructs in actual sites is done to indicate that such development
could reasonably fit within the region. However, the sites selected
are not meant to be actual recommendations for construct development,
but merely representative locations. The project team has not
performed any of the necessary detailed planning, environmental or
design analyses that would be required to recommend particular
development sites.
Two alternative scenarios of construct development were used in
this analysis. Scenario 1 tests the effects of channeling some of the
growth which would occur in suburban areas under trend conditions into
the urban areas of New Brunswick and Trenton, on the hypothesis that
placing more development in the urban areas with higher land use
densities and more transit services would help reduce auto travel. It
is also a policy goal of the emerging New Jersey State Development and
Redevelopment Plan.
Scenario 2 assumes that the cities will grow only at their expected
trend rates, with suburban constructs absorbing all the remaining
growth. Both scenarios take as given the regional projections of
employment and household growth. Therefore, the total growth
projected for the year 2010 in the Trend, Scenario 1 and Scenario 2
are all the same. It is the disaggregate distribution of development
that differs among the Trend and two scenarios. (NOTE: The analysis of
the data published in this report does not include the cities. See
Chapter V, Defining the Study Area).
1. Scenario 1: Constructs and Major Urban Growth
a. The Urban Growth Component
Preceding the assignment of constructs, it was necessary to make
some assumptions about the major urban centers in the region, New
Brunswick and Trenton. Their projected growth rates
41
Table 4
2010 Trend Conditions for MSM Region Communities
Municipality Non-Retail Employment Retail Employment Households
East Windsor 12,097 1,403 13,562
Ewing 30,949 2,791 14,512
Hamilton 27,722 6,568 40,394
Hightstown 3,680 1,000 1,819
Hopewell Township & Borough 4,426 394 7,231
Lawrence 22,170 7,180 11,235
Pennington 3,510 40 1,113
Princeton Township & Borough 28,263 1,837 13,295
Trenton 65,644 4,256 39,619
Washington 3,340 600 4,159
West Windsor 23,392 2,128 9,327
Mercer County 225,193 28,197 156,266
Franklin 24,221 2,389 23,293
Hillsborough 9,311 1,339 14,249
Manville 3,347 283 4,133
Millstone 191 19 187
Montgomery & Rocky Hill 9,961 1,149 5,548
South Bound Brook 1,011 69 1,669
Somerset County (part) 48,042 5,248 49,079
Cranbury 7,360 316 2,165
East Brunswick 22,211 10,551 17,768
Helmetta 214 11 986
Jamesburg 2,270 433 2,215
Milltown 2,615 242 3,000
Monroe 9,913 2,391 14,215
New Brunswick 34,002 3,013 16,461
North Brunswick 30,665 3,667 15,223
Plainsboro 32,097 1,452 13,566
South Brunswick 42,262 1,801 15,645
South River 2,829 423 5,504
Spotswood 2,508 454 3,354
Middlesex County (part) 188,946 24,754 110,102
MSM Region Total 462,181 58,199 315,447
42
for the year 2010 are shown in Table 4, and are taken from the State
Plan's prediction (not policy) of little growth in those areas. These
became our 2010 Trend levels for the cities.
MSM's REGIONAL FORUM, discussed in Chapter II, developed a growth
policy scenario which placed much higher employment and population in
these two cities than did the trend estimates. These became our
Scenario 1 levels for the cities.
The remaining regional growth was distributed among constructs.
b. The Construct Component
The assignment of constructs was performed by the project team,
with input from the steering committee. As a first step, three
Transit Constructs were found to be a reasonable number for the
region. Two were located on the Northeast Corridor rail line (at
Princeton Junction in West Windsor and the projected station for
Monmouth Junction in South Brunswick), and one was positioned near
Exit 8 of the New Jersey Turnpike, where there is convenient bus
service to New York City.
Next, eight Short Drive Constructs were assigned, absorbing
virtually all the remaining regional employment growth not picked up
by the cities and the Transit Constructs. Short Drive Constructs were
placed where employment centers are already emerging, and/or there is
some major highway access.
Finally, the remaining population growth (and a small amount of
employment growth) was distributed into eight Walking Constructs.
Figure 13 shows a map of the locations of these constructs, while the
municipalities in which they are located are listed in Table 5.
2. Scenario 2: Constructs with. Trend Urban Growth
In Scenario 2, the year 2010 Trend growth assumptions for New
Brunswick and Trenton were assumed to prevail, meaning that the
Regional FORUM's goal for a major resurgence of the cities is not met.
Instead, the same level of suburban growth as projected in the Trend
is expected in this scenario, and all of the 1988-2010 growth
increment (except for the small amount predicted for the cities) is
absorbed by the constructs. Figure 14 shows how employment and
population levels in Trenton and New Brunswick differ among the
Baseline 1988, the 2010 Trend, and Scenarios 1 and 2.
It was assumed that the same number of constructs would be sited in
the region in Scenario 2 as in Scenario 1, at the same locations. But
in order to absorb the larger amount of suburban growth, a number of
the constructs have been increased in size. It should be noted,
however, that although the land area was increased, the land use
density (i.e. average dwelling units per acre) was maintained.
Finally, Tables 6 and 7 show the differences in the total level of
employment and households among the Baseline 1988, the year 2010
Trend, Scenario 1 and Scenario 2, aggregated at the municipal level.
Detailed descriptions of these forecasts by traffic zone are included
in Appendices D and E.
43
Figure 13
Click HERE for graphic.
44
Table 5
Location of Constructs in Both Scenarios 1 and 2
Number of constructs in Ealch Municipality of this Type:
Transit Short-Drive Walking
Municipality Construct Construct Construct
East Windsor 1(bus) - -
Hopewell Township - 1 2
Lawrence - 1 -
Washington - 1 1
West Windsor 1(rail) - -
Franklin - 1 1
Hillsborough - 1 -
Montgomery - - 2
Cranbury - - 1
North Brunswick - 1 -
Plainsboro - 1 -
South Brunswick 1(rail) 1 1
NOTE: The site selected are not meant to be actual recommendations
for construct development, merely representative locations.
The project team has not performed any of the necessary
detailed planning, environmental or design analyses that
would be requied to recommend particular development sites.
45
Figure 14
Employment and Household Projections for Trenton and New Brunswick
Click HERE for graphic.
46
Table 6
Current and Projected Employment Under Different Scenarios
Construct Total Employment:
Municipality Types 1988 2010 Trend 2010 Scen. 1 2010 Scen. 2
East Windsor T 8,463 13,500 21,563 27,031
Ewing 28,660 33,740 28,660 28,660
Hamilton 27,925 34,290 27,925 27,925
Hightstown 2,855 4,680 2,855 2,855
Hopewell Twnshp/Boro D,2W 3,467 4,820 13,427 17,656
Lawrence D 21,301 29,350 30,301 34,006
Pennington 1,636 3,550 1,636 1,636
Princeton Twnshp/Boro 22,262 30,100 22,262 22,262
Trenton 54,847 69,900 87,817 69,900
Washington D,W 2,101 3,940 11,830 15,959
West Windsor T 12,162 25,520 25,262 30,731
Mercer County 185,679 253,390 273,538 278,621
Franklin D,W 23,942 26,610 33,672 37,801
Hillsborough D 4,380 10,650 13,880 17,899
Manville 1,279 3,630 1,279 1,279
Millstone 54 210 54 54
Montgomery/Rocky Hill 2W 7,980 11,110 8,440 8,660
South Bound Brook 495 1,080 495 495
Somerset County (part) 38,130 53,290 57,820 66,188
Cranbury W 6,703 7,676 6,933 7,043
East Brunswick 25,319 32,762 25,319 25,319
Helmetta 165 225 165 165
Jamesburg 2,082 2,703 2,082 2,082
Milltown W 2,657 2,857 2,657 2,657
Monroe 1,946 12,304 1,942 1,942
New Brunswick 35,252 37,015 68,223 37,015
North Brunswick D 15,775 34,332 25,275 26,311
Plainsboro D 6,999 33,549 16,499 20,518
South Brunswick T 12,686 44,063 35,516 45,115
South River 2,237 3,252 2,237 ,237
Spotswood 2,174 2,962 2,174 2,174
Middlesex County (part) 113,995 213,700 189,022 175,561
MSM Region Total 337,804 520,380 520,380 520,380
T = transit construct, W = walking construct, D = short-drive construct
47
Table 7
Current and Projected Households Under Different Scenarios
Construct Total Households:
Municipality Types 1988 201O Trend 201O Scen.1 201O Scen.2
East Windsor T 8,666 13,562 14,666 17,994
Ewing 12,541 14,512 12,541 12,541
Hamilton 31,336 40,394 31,336 31,336
Hightstown 1,818 1,819 1,818 1,818
Hopewell Twnshp/Boro D,2W 4,673 7,231 10,673 13,976
Lawrence D 8,616 11,235 11,416 12,958
Pennington 872 1,113 872 872
Princeton Twnshp/Boro 8,804 13,295 8,804 8,804
Trenton 33,952 39,619 53,359 39,619
Washington D,W 2,250 43,159 6,650 9,073
West Windsor T 4,436 9,327 10,436 13,764
Mercer County 117,964 156,266 162,571 162,755
Franklin D,W 13,502 23,293 17,902 20,325
Hillsborough D 9,165 14,249 11,965 13,507
Manville 3,868 4,133 3,868 3,868
Millstone 180 187 180 180
Montgomery/Rocky Hill 2W 3,290 5,548 6,490 8,253
South Bound Brook 1,502 1,669 1,502 1,502
Somerset County (part) 31,507 49,079 41,907 47,635
Cranbury W 913 2,165 2,513 3,394
East Brunswick 13,555 17,768 13,555 13,555
Helmetta 439 986 439 439
Jamesburg 1,688 2,215 1,688 1,688
Milltown W 2,412 3,000 2,412 2,412
Monroe 8,640 14,215 8,640 8,640
New Brunswick 12,682 16,461 32,090 16,462
North Brunswick D 10,730 15,223 13,530 15,072
Plainsboro D 6,833 13,566 9,633 11,175
South Brunswick T 8,341 15,645 18,741 24,493
South River 4,823 5,504 4,823 4,823
Spotswood 2,904 3,354 2,904 2,904
Middlesex County (part) 73,960 110,102 110,968 105,057
MSM Region Total 223,431 315,447 315,447 315,447
T = transit construct, W = walking construct, D = short-drive construct
48
CHAPTER V:
ANALYZING THE TRANSPORTATION IMPACTS OF CONSTRUCT SCENARIOS
A. Defining the Study Area
In analyzing the results of the constructs, a somewhat smaller
study area was selected from the MSM region. For technical reasons,
the cities of New Brunswick and Trenton are excluded. The reasons for
examining this smaller, non-urban study area are twofold:
- First, the study was funded to analyze suburban land use trends
and alternatives. Although a key assumption is made in Scenario
1 regarding the growth of the cities, it was not within the
scope of this analysis to assess the specific impacts of that
growth.
- Second, the vehicle trip generation rates used in the analysis
re
