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Development and Application of Trip Generation Rates - Final Report January 1985





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   Notice:  This document is disseminated under the sponsorship of the
   Department of Transportation  in the interest of information
   exchange.  The United States Government assumes no liability for the
   contents or use thereof.





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                             ACKNOWLEDGMENTS

Kellerco is most appreciative for the assistance rendered by the U.S.
Department of Transportation, the Institute of Transportation Engineers,
and the staffs of several agencies throughout the country.  U.S. DOT
staff who provided assistance included Ms. Louise Skinner, Mr. Leroy
Chimini, Mr. Carl Shea, Mr. Christopher Fleet and Mr. George Schoener. 
Mr. Mark Norman of ITE provided valuable assistance.  Dr. Everett Carter
and Mr. Abdulla Meer acted as consultants to Kellerco.  Mr. Sanjeev
Malhotra provided research assistance on the study.  Mr. Joe Mehra was
the Principal Investigator and Mr. C. Richard Keller was the Principal-
In-Charge.





                            TABLE OF CONTENTS
                                                                Page No.
I.   INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . .1

     OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

II.  ANALYSES OF TRIP RATE DATA . . . . . . . . . . . . . . . . . . .5

     DATA SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . .5

     UPDATING TRIP RATES. . . . . . . . . . . . . . . . . . . . . . .5

III. TRIP GENERATION RATES. . . . . . . . . . . . . . . . . . . . . .9

     USE OF TRIP RATES. . . . . . . . . . . . . . . . . . . . . . . .9

IV.  OTHER FACTORS INFLUENCING TRIP RATES .. .... . . . . . . . . . 30

     MULTI-USE DEVELOPMENT . .... . . . . . . . . . . . . . . . . . 30

     SITE DEVELOPMENT CAPTURE RATES FOR PASS-BY TRAFFIC . . . . . . 36

REFERENCES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

APPENDICES

     A  List of Agencies. . . . . . . . . . . . . . . . . . . . .  A-1
     B  Trip Rate Analysis Methodology. . . . . . . . . . . . . . .B-1
     C  Recommendations for Further Research. . . . . . . . . . . .C-1

                                   iii





                             LIST OF FIGURES

Figure No.                                                      Page No.
     1  NORTHERN VIRGINIA PUD . . . . . . . . . . . . . . . . . . . 31
     2  RICHMOND, VIRGINIA PUD. . . . . . . . . . . . . . . . . . . 33
     3  ILLUSTRATIVE RELATIONSHIP BETWEEN
        PERCENTAGES OF INTERNAL TRIPS AND RATIO
        OF COMMERCIAL SPACE TO NUMBER OF
        RESIDENTIAL UNITS . . . . . . . . . . . . . . . . . . . . . 35

                                   iv





                             LIST OF TABLES

  Table No                                                      Page No.
     1  DATA SOURCES. . . . . . . . . . . . . . . . . . . . . . . . .6

     2  DAILY TRIP RATES AS A FUNCTION OF
        TRANSIT AVAILABILITY. . . . . . . . . . . . . . . . . . . . .8

     3  TRIP GENERATION RATES . . . . . . . . . . . . . . . . . .10-23

     3a ADJUSTMENT FACTORS FOR RESIDENTIAL
        CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . 27

     4  TYPICAL LAND USE DENSITIES. . . . . . . . . . . . . . . . . 28

     5  APPLICATION OF ADJUSTMENT FACTORS . . . . . . . . . . . . . 29

     6  EXTERNAL TRIPS GENERATED BY USES IN A PUD . . . . . . . . . 34

     7  SITE DEVELOPMENT CAPTURE RATE
        FROM PASS-BY TRAFFIC. . . . . . . . . . . . . . . . . . . . 37

 APPENDICES

     B-1    TEST OF SIGNIFICANT DIFFERENCES BETWEEN
            PRE-1973 AND POST-1973 DATA . . . . . . . . . . . . . .B-4

     B-2    TEST OF SIGNIFICANT DIFFERENCES BY LOCATION
            BETWEEN PRE-1973 AND POST-1973 DATA . . . . . . . . . .B-5

     B-3    MULTIPLE REGRESSION ANALYSIS STATISTICS FOR
            RESIDENTIAL USES. . . . . . . . . . . . . . . . . . .. B-7

     B-4    TRIP RATES AS A FUNCTION OF MARKET VALUES OF
            SINGLE FAMILY DETACHED RESIDENTIAL DWELLING . . . . . .B-8

                                    v








          DEVELOPMENT AND APPLICATION OF TRIP GENERATION RATES

I. INTRODUCTION

Local agencies are continually facing the need to address the physical
condition and service capabilities of the streets and highways in their
jurisdictions.  Recently this concern has turned to the rapidly
developing suburbs of metropolitan areas and the access needs of new
development.  Related to this are the issues of zoning variances and
joint public/private funding for highway improvements to support these
developments.  Regional planning agencies are being called on more
frequently to provide technical assistance and service to sub-regional
areas and local jurisdictions.  Local cities and counties face the need
for accurate technical procedures to analyze 'the potential impacts of
new development.

This publication and its companion document, the 'Site Impact Traffic
Evaluation (S.I.T.E.) Handbook". provide guidance on site access
analysis procedures.  This report presents updated 'trip generation
rates along with factors for adjusting trip rates due to variations in
residential characteristics The use of trip rates is also described. 
The S.I.T.E. Handbook presents a seven phased site access study process
including a trip generation rate development procedure (50).  Four case
studies are presented that demonstrate the use of trip generation rates
and also analyze the sensitivity of site-related traffic to trip rates,
trip distribution patterns and other key variables.  Additional and
related publications include:

   -  The ITE trip rates publication: 'Trip Generation - An
      Informational Report", Third Edition, 1982 (45)
   -  "Using the ITE Trip Generation Report" prepared by Carl Buttke for
      ITE, July 1984 (5)
   -  NCHRP Report 187 "Quick Response Urban Travel Estimation
      Techniques and Transferable Parameters: User's Guide" 1978. (83)

These publications should be collectively used for guidance and not
relied upon' as the sole source of information for trip rate information
in site access analyses.  Where local data and procedures are available,
they should be used if the analyst considers them to be more accurate.

OVERVIEW

There are many methods for collecting trip generation rates, ranging
from driveway (ground) vehicular counts to regional home interview
surveys.  Driveway vehicular counts of traffic

                                    1





entering and leaving development sites have been collected for many land
uses. Manual counts or automatic traffic recorders are used to
collect  traffic data on driveways during peak hours of adjacent
street   traffic and/or the generator and sometimes over a twenty-four
hour period.  The traffic data for the cordoned site along with the
background information on each site (such as dwelling units, gross floor
area, number of employees and acres of land) are utilized to estimate
vehicle trip rates per dwelling unit (or other independent variable). 
Most of these ground count based rates are compiled in such documents as
the Institute of Transportation Engineers (ITE) "Trip Generation - An
Informational Report" (45) and numerous locally developed documents. 
These rates, when applied to future land uses, result in an estimate of
future daily and peak hour trips.  Regional home interview surveys are
not covered in this report.  They provide information at the individual
household level and are generally used to model trip generation
relationships with various socioeconomic factors and land use
characteristics.  These trip generation relationships are generally used
for long range comprehensive planning.

Several concerns have been raised regarding existing trip generation
rate data:

   -  Variability among trip generation rate sources and geographic
      locations as well as differences between these rates and other
      national data sources, such as the 1977 Nationwide Personal
      Transportation Survey (NPTS).
   -  Effects of older data (collected in the 1960's) included in the
      more current trip generation rates.
   -  Lack of detailed guidelines on the use of existing trip generation
      rate data.

This publication provides guidance on the use of trip generation rates
in light of these concerns.  In addition three related issues are also
addressed:

   -  The effect of socioeconomic variables on residential trip
      generation rates.
   -  Reduced external trips generated by multi-use centers (i.e. a
      percentage of the trips generated by a multi-use center are
      internal and remain on site).
   -  Capture rates for "pass-by" traffic (i.e. trips attracted to the
      development from traffic normally passing-by the site).

This technical concern for trip rate accuracy has emerged coincidentally
with increased emphasis on site access studies.  To illustrate this
emerging issue, the FHWA has completed a

                                    2





study to: 1) investigate the existing uses of private funds for highway
improvements 2) evaluate the mechanisms-used to obtain private funding
and, 3) to recommend improvements for which private funding may be used
(52).

A key issue in the technical process is trip generation rates and their
subsequent role in the estimation of traffic impact and needed road
improvements.  Since trip rates are so important to local zoning
regulations it is essential-for the success of this new concept of
private/public cost sharing to have accurate trip rate information.  In
most areas the ITE Trip Generation Report is considered the reference
manual on trip generation.  Accurate trip rates will enhance the
application and accuracy of the quick response techniques and
significantly aid site access analyses in the United States -- and also
facilitate equitable cost sharing negotiations between public and
private interests.

The findings of this study have implications for the public and private
sectors in achieving cost effective roadway improvements.  The trip
rates and their adjustment factors developed in this study can be used
to:

   -  conduct site access studies including the estimation of traffic
      generated by either a single use! multi-use or planned unit
      development.
   -  forecast daily and peak hour traffic volumes for the geometric
      design of traffic circulation and access plans.
   -  evaluate on-site alternative land use development conditions to
      optimize or minimize the traffic impact on the adjacent highway
      network.
   -  aid in the determination of the private developer's share in local
      transportation improvements.
   -  estimate daily and peak hour trip rates and traffic flows for
      transportation corridor and sub-area analyses.

The S.I.T.E. Handbook presents details on the uses of trip generation
rates (50).

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II.  ANALYSES OF TRIP RATE DATA

DATA SOURCES

The major data source for the trip rates presented in this report was
the ITE data base.  An extensive literature review was conducted, and
agency contacts were made to identify trip generation data that were
collected since the latest update of the ITE trip rates publication.(45)
This search resulted in the identification of over 500 references. 
Approximately seventy of these references included relevant trip
generation data.  Accordingly, it was decided to augment the ITE data
base with the new data collected.  All new data collected were checked
against the existing ITE data base to avoid duplication of data sources. 
The data sources that were not duplicative of the ITE data base are
presented in Table 1. It should be noted that NCHRP Report 187, Table I
(83), incorporates ITE trip rate data as well as other sources.  The
other sources in NCHRP 187 were neither described in the NCHRP Report
nor available through the Transportation Research Board.  Therefore,
NCHRP 187 trip rate data could not be included in the data base for this
report.

Because of concerns about travel habits changing due to the energy
crisis, analyses comparing older data (pre-1973) and the newer data
(post-1973) were performed.  Based on statistical tests such as t-test
and f-ratios, it was concluded that there were no significant
differences between the mean trip rates of older data (pre-1973) and the
newer data (post-1973) for all land uses analyzed. (See Appendix B for a
detailed analysis.) In some cases, the mean trip rates appeared to be
different but due to a large standard deviation, the statistical tests
indicated no significant difference.  Accordingly, all data regardless
of age were used to develop the updated trip rates.  Data on land uses
not included in ITE were collected and analyzed.  These land uses
include high technology office buildings, townhouse office buildings,
bowling alleys, department stores, drug stores, beauty salons, dry
cleaners and printing shops.  Some of these land uses have limited
sample sizes and the trip rates are not included in this report.

UPDATING TRIP RATES

Trip generation rates for non-residential uses were estimated for each
of the three variables: location, auto occupancy and transit usage. 
Location was categorized as urban, suburban and rural.  Data on location
were generally available for industrial parks, hotels, hospitals, office
buildings, and shopping centers in the range of 100,000 to 499,999
square feet of gross leasable area (GLA).

                                    5





                                 TABLE 1
                              DATA SOURCES

   SOURCE                                   SURVEY TYPE  REFERENCE [1]

   Prince George's County, Maryland            Driveway             47
   Maryland-National Capital Park
      and Planning Commission                  Driveway             48
   East-West Gateway Coordinating
      Council                                  Driveway             29
   Anne Arundel County, Maryland               Driveway             90
   Palm Beach County, Florida                  Driveway          51,53
   Virginia Department of Highway
      & Transportation                         Driveway             80
   Connecticut DOT                       Home Interview             21
   Southeast Michigan COG                Home Interview             79
   Metropolitan Transportation
      Commission                         Home Interview             54
   Maryland DOT                                Driveway             58
   California DOT                              Driveway             11
   San Diego Association of                   Driveway/
      Governments                        Home Interview       20,43,74
   Delaware DOT                                Driveway             27
   Kellerco Data  Files                        Driveway             49
   New Hampshire  Department of
      Public Works and Highways                Driveway             64
   West Virginia DOT                           Driveway             94
   Chicago                                    Driveway/
      Home Interview                                             16,17
   Cincinnati, Ohio                      Home Interview             14
   Richmond, Virginia                         Driveway/
      Home Interview                                                70
   Washington COG                              Driveway             63
   Virginia Highway and Transportation
      Research Council                         Driveway          92,93
   Fairfax County, Virginia                    Driveway             89
   Baltimore Disaggregate Data Set       Home Interview             31

   [1]  See list of references at the end of the Report

                                    6





Auto occupancy data were available for manufacturing land use only. 
However, the sample size was not adequate for any statistical tests.

Transit availability data for industrial/manufacturing uses and shopping
centers in the range of 100,000 to 499,999 square feet of GLA were
included in the data base.  The summary of mean daily trip rates with
and without transit availability are presented in Table 2. For the
industrial park, the mean daily, trip rates for sites not served by
transit were higher than sites served by transit.  This is contrary to
what is generally expected; however, data were not available to
determine the reasons for this anomaly.  T-tests were carried out to
determine if a significant difference existed between the mean trip
rates of sites with and without transit available.  In all cases the
statistical tests showed that the means are not significantly different. 
It should be noted that although. the means are intuitively different,
the high standard deviations result in the finding of no statistical
differences.

The results of the updating analyses are presented in the next Chapter
along with the use of the updated trip fates.

                                    7





                                 TABLE 2
                     DAILY TRIP RATES AS A FUNCTION
                         OF TRANSIT AVAILABILITY


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                                    8





III.  TRIP GENERATION RATES

This chapter presents the results of the trip generation analyses as the
updated Table I of NCHRP Report 187 (83).  The updated trip rates are
presented in Table 3.

For each land use, the following data are included:

     -  Corresponding ITE land use code(s)
     -  The weighted mean daily trip rates for one or more independent
        variables, such as dwelling units, acres, employees and square-
        feet of gross floor area
     -  The minimum daily trip rate in the sample data
     -  The maximum daily trip rate in the sample data
     -  The standard deviation about the mean trip rate
     -  The standard error of mean which is estimated as (standard
        deviation)/(square root of number in sample)
     -  The weighted mean trip rates for the AM and PM peak hour of the
        adjacent street traffic. The directional distribution of trips
        is also presented
     -  The weighted mean trip rate for the peak one hour of the
        generator is included along with the directional distribution of
        trips
     -  Additional adjustment factors are provided for residential use
        characteristics such as household size, vehicle ownership and
        residential density.  These adjustment factors are presented in
        Table 3a. it should be noted that the adjustment factors for
        residential characteristics are to be added (or subtracted) from
        the daily trip rates.  The application of these factors is
        described in a later section.

USE OF TRIP RATES

The trip generation rates presented in Table 3 should be used with care,
If local data are available for a similar site. then the local data
should be used.  Table 3 can be used to estimate the amount of traffic
that may be generated by a specific land use or site.  Appropriate
adjustment factors for residential characteristics may be applied. 
Further adjustments due to increased ridesharing or proximity to transit
may be applied using other techniques such as the office trip generation
rate analysis technique, described in the SITE.Handbook, (50) and/or
Using The ITE Trip Generation Report (5).  This reference (5) describes
the uses of trip generation rates including methodologies for adjusting
trip rates for Transportation Systems Management (TSM) actions such as
ridesharing, etc.  The following sections briefly describe the use of
trip rates presented in Table 3.

                                    9



                                 TABLE 3

                           VEHICLE TRIPS PER DAY
  LAND USE                  TO & FROM LAND USE
  GENERATOR                (Rate/Unit as noted)        STATISTICS
  ------------      ---------------------------   ---------------------
                                                           STD
                                                          ERROR# OBS.
  DESCRIPTION                                       STD    OF      IN
  & ITE CODE        UNITS   MEAN    MIN    MAX     DEV.   MEAN SAMPLE

PORTS & TERMINALS(000)

   Water Ports      BOSBER 171.52  38.60  338.57  112.98  42.70   7
       010          ACRE    11.95   4.95   19.47    5.45   2.06  71

    Air Ports       CFL/DY  70.85  51.33   78.44   13.59   7.85   3
       020          FLT/DY   3.05   0.96   31.38    8.83   2.66  11
                    EMP     21.45  11.55  284.29  102.29  38.66   7
                    ACRE     4.77   0.99   24.89    8.25   2.49  11

  Comm Airport      CFL/DY 122.21  99.50  138.74   22.55  13.02   3
       021          FLT/DY   8.34   1.62  122.97   60.71  35.05   3
                    EMP     15.39  14.11   22.94    6.25   4.42   2
                    ACRE    11.48   9.13   16.22    3.63   2.10   3

 Gen Avi Airport    FLT/DY   2.50   *       *      NA     NA      *
       022          EMP      6.50   *       *      NA     NA      *
                    ACRE     3.60   *       *      NA     NA      *

 Truck Terminals    1K SF    9.86  NA      NA      NA     NA      1
       030          EMP      6.99   4.22   47.29   30.45  21.53   2
                    ACRE    81.86  66.20  100.08   23.96  16.94   2

 INDUSTRIAL(100)

 Gen Lght Indus     1K SF    6.98   1.58   16.88    4.44   1.05  18
       110          EMP      4.50   1.53   10.42    2.12   0.49  19
                    ACRE    76.03   5.21  159.38   43.90  10.07  19

 Gen Heavy Indus    1K SF    1.50   0.58    1.84    0.69   0.40   3
       120          EMP      2.05   0.75   11.05    4.99   2.50   4
                    ACRE    15.62   1.66   55.13   24.71  12.36   4

   Indus Park       1K SF    7.00   0.91   36.97    7.71   1.12  47
       130          EMP      3.59   1.37    8.80    1.92   0.29  45
                    ACRE    62.82  13.87 1272.63  209.24  32.68  41

    Manufact        1K SF    3.85   0.50   52.05    6.90   0.89  60
       140          EMP      2.09   0.60    6.66    1.21   0.16  60
                    ACRE    38.88   2.54  396.00   69.43   9.28  56

    Warehouse       1K SF    4.88   1.51   17.00    3.76   0.97  15
       150          EMP      3.89   1.47   15.71    3.74   0.97  15
                    ACRE    56.08  20.23  255.80   59.64  15.94  14
      ____________________________________________________________

                            LEGEND FOR UNITS:
  1K SF    1,000 SQ. FT. GFA       CFL/DY  COMMERCIAL FLIGHT PER DAY
  ACRE     ACRE                    CIVEMP  CIVILIAN EMPLOYEE
  BED      HOSPITAL BED            DEFEMP  DEFENSE FORCES EMPLOYEE
  BOSBER   BOAT-OR SHIP BERTH      DU      DWELLING UNIT

                                   10





                          TRIP GENERATION RATES


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                          Vehicle Trips Per...
  EMP      EMPLOYEE                ROOM    HOTEL/MOTEL ROOM
  FLT/DY   FLIGHT PER DAY          SEAT    RESTAURANT SEAT

  PRKSPC   PARKING SPACE           STDNT   STUDENT
  PUMP     GAS(OR DIESEL) PUMP     STN     GAS(OR DIESEL) STATION


                                   11





                           TABLE 3 , continued

                          VEHICLE TRIPS PER DAY
      LAND USE             TO & FROM LAND USE
      GENERATOR           (Rate/Unit as noted)         STATISTICS
 ------------------      ---------------------------------------------------
                                                           STD
                                                          ERROR # OBS.
     DESCRIPTION                                    STD    OF       IN
     & ITE CODE    UNITS    MEAN   MIN    MAX      DEV.   MEAN  SAMPLE

  RESIDENTIAL(200)

  S-F Det Hous      DU     10.03   4.31   21.90    2.37    0.13   313
  210               ACRE   26.18   1.82  275.19   31.15    2.82   122

  Urban             DU     11.28
                    ACRE   29.45
  Suburban          DU      9.06
                    ACRE   23.64
  Rural             DU      9.73
                    ACRE   25.40

  Apartment         DU      6.11   0.54   12.34    1.92    0.17   122
  220               ACRE   23.79   1.82  361.83   67.98    8.37    66

  Urban             DU      6.87
                    ACRE   26.76
  Suburban          DU      5.52
                    ACRE   21.48
  Rural             DU      5.93
                    ACRE   23.08

  Condomin          DU      5.40   0.57   11.79    2.28    0.31    55
  230               ACRE   68.04  14.81  337.66   74.29   17.04    19
  Urban             DU      6.08
                    ACRE   76.55
  Suburban          DU      4.88
                    ACRE   61.44

  Mobile Home       DU      4.78   2.29    7.60    1.44    0.28    26
  240               ACRE    9.13  15.86   85.89   17.19    3.19    29

  Retire Comm       DU      3.30   2.80    9.90   NA      NA        3
  250

  Plan Unit Dev     DU      7.49   5.23   14.38    2.62    0.70    14
  270               ACRE   46.78  41.85   50.80    4.24    2.12     4
  (Suburban)


                            LEGEND FOR UNITS:

  1K SF    1,000 SQ. FT. GFA       CFL/DY  COMMERCIAL FLIGHT PER DAY
  ACRE     ACRE                    CIVEMP  CIVILIAN EMPLOYEE
  BED      HOSPITAL BED            DEFEMP  DEFENSE FORCES EMPLOYEE
  BOSBER   BOAT OR SHIP BERTH      DU      DWELLING UNIT

                                   12





                          TRIP GENERATION RATES


Click HERE for graphic.


                          Vehicle Trips Per...

  EMP      EMPLOYEE                ROOM    HOTEL/MOTEL ROOM
  FLT/DY   FLIGHT PER DAY          SEAT    RESTAURANT SEAT
  PRKSPC   PARKING SPACE           STDNT   STUDENT
  PUMP     GAS(OR DIESEL) PUMP     STN     GAS(OR DIESEL) STATION

                                   13





                           TABLE 3 , continued

                          VEHICLE TRIPS PER DAY
      LAND USE             TO & FROM LAND USE
      GENERATOR           (Rate/Unit as noted)         STATISTICS
 ------------------           ----------------------------------------------
         STD
        ERROR     # OBS.
     DESCRIPTION    STD      OF    IN
     & ITE CODE    UNITS    MEAN   MIN    MAX      DEV.   MEAN  SAMPLE

  LODGING(300)
  Hotel             ROOM    8.70   5.31    9.58    1.58    0.60     7
  310               EMP    14.34   8.85   24.47    6.13    2.74     5
                    ACRE 1430.19 755.38 1663.55  395.72  197.86     4

  Urban             ROOM    8.68
                    EMP    14.31
                    ACRE 1427.33
  Suburban          ROOM    9.34
  EMP               15.39
                    ACRE  534.59

  Motel             ROOM    6.13   4.17   10.04    2.54    0.90     8
  320               EMP    12.81   7.20   41.00   10.69    3.38    10
                    ACRE  180.71  38.41  364.44  106.57   32.13    11

  Resort Hotel      ROOM   18.40   7.11   52.41   14.33    5.07     8
  330               EMP    10.27  NA      NA      NA      NA        1
                    ACRE  237.96  33.42 1811.11  568.51  201.00     8

  RECREATION(400)

  Parks             PRKSPC  7.81   2.93   24.28    6.74    2.25     9
  410               EMP    96.17  42.35  183.62   59.56   29.78     4
                    ACRE   30.37   2.99  214.55   62.22   16.07    15


  City Parks        PRKSPC  6.50   1.91   12.55    5.51    3.18     3
  411               EMP    51.10  47.06   66.67    9.97    5.76     3
                    ACRE    3.66   1.04  129.83   55.36   24.76     5

  County Parks      PRKSPC  2.18   0.42   21.00    5.58    1.61    12
  412               EMP    26.46  23.33  183.33   50.32   13.96    13
                    ACRE    5.09   0.17   81.24   21.12    5.12    17

  State Parks       PRKSPC  1.15   0.40    3.13    0.97    0.34     8
  413               EMP    60.20  21.93  183.33   67.14   20.24    11
                    ACRE    0.69   0.05   16.67    6.51    1.81    13

  Marinas           BOSBER  2.96   1.91    0.4     2.33    0.70    11
  420               EMP   251.47 231.50  276.67   24.13   12.06     4
                    ACRE   20.92  10.32   75.45   32.64   18.84     3

  Golf Course       PRKSPC  5.32   1.75   16.39    3.47    0.87    16
  430               EMP    20.63  10.90   75.00   18.27    5.07    13
                    ACRE    6.91   2.33   22.78    4.42    0.94    22


                            LEGEND FOR UNITS:
  1K SF    1,000 SQ. FT. GFA       CFL/DY COMMERCIAL FLIGHT PER DAY
  ACRE     ACRE                    CIVEMP  CIVILIAN EMPLOYEE
  BED      HOSPITAL BED            DEFEMP  DEFENSE FORCES EMPLOYEE
  BOSBER   BOAT OR SHIP BERTH      DU      DWELLING UNIT

                                   14





                          TRIP GENERATION RATES


Click HERE for graphic.


                          Vehicle Trips Per...

  EMP      EMPLOYEE                ROOM    HOTEL/MOTEL ROOM
  FLT/DY   FLIGHT PER DAY          SEAT    RESTAURANT SEAT
  PRKSPC   PARKING SPACE           STDNT   STUDENT
  PUMP     GAS(OR DIESEL) PUMP     STN     GAS(OR DIESEL) STATION

                                   15





                                 TABLE 3continued

                          VEHICLE TRIPS PER DAY
      LAND USE             TO & FROM LAND USE
      GENERATOR           (Rate/Unit as noted)         STATISTICS
 ------------------         -------------------------------------------------

                                                           STD
                                                          ERROR # OBS.
     DESCRIPTION                                    STD    OF       IN
     & ITE CODE    UNITS    MEAN   MIN    MAX      DEV.   MEAN  SAMPLE

  INSTITUTIONS(500)

  Military Base     EMP     1.80                  NA      NA         
  501               DEFEMP  2.20                  NA      NA         
                    CIVEMP  7.10                  NA      NA         

  Day Care Cen      STDNT   4.98   4.10    7.10    1.22    0.55     5
  511               1K SF  79.14  57.20  125.10   26.40   11.81     5

  (Suburban)        EMP    33.20  25.60   50.40   12.73    5.70     5
  Elem School       STDNT   1.02   0.45    1.82    0.35    0.06    40
  520               EMP    13.10   4.47   26.37    5.28    0.84    40
                    ACRE   33.69   3.72  123.80   28.41    4.49    40

  High School       STDNT   1.38   0.71    2.49    0.52    0.10    27
  530               EMP    16.79   4.28   32.87    6.52    1.26    27
                    ACRE   23.81   1.02  103.20   26.71    5.97    20

  Jr Comm Coll      STDNT   1.58   0.94   27.52    5.65    1.23    21
  540               EMP    10.06  NA      NA      NA      NA        1
                    ACRE   11.90  NA      NA      NA      NA        1

  Universit         STDNT   2.41   1.40    3.89    0.92    0.37     6
  550               EMP    14.35  NA      NA      NA      NA        1
                    ACRE  107.28  NA      NA      NA      NA        1

  Libraries         EMP    49.51  36.80   81.91   19.65    9.83     4
  590               ACRE  343.78 221.65  909.00  296.91  148.46     4

  MEDICAL(600)

  Hospital          BED    11.84   3.00   32.83    7.46    1.49    25
  610               EMP     5.03   2.17   11.11    2.35    0.49    23
                    ACRE  167.73  24.07 1012.50  229.97   51.42    20

  Urban             BED    13.08
                    EMP     5.56
                    ACRE  185.34
  Suburban          BED    11.21
                    EMP     4.76
                    ACRE  158.86

  
  Nurs Home         BED     2.60   1.88    3.97    0.57    0.13    18
  620               EMP     4.03   2.53    9.69    1.99    0.47    18

  Clinics           BED    15.96  NA      NA      NA      NA        1
  630               EMP     5.89  NA      NA      NA      NA        1
                    ACRE   91.19  NA      NA      NA      NA        1


                            LEGEND FOR UNITS:

  1K SF    1,000 SQ. FT. GFA       CFL/DY  COMMERCIAL FLIGHT PER DAY
  ACRE     ACRE                    CIVEMP  CIVILIAN EMPLOYEE
  BED      HOSPITAL BED            DEFEMP  DEFENSE FORCES EMPLOYEE
  BOSBER   BOAT OR SHIP BERTH      DU      DWELLING UNIT

                                   16





                          TRIP GENERATION RATES


Click HERE for graphic.


                          Vehicle Trips Per...

  EMP      EMPLOYEE                ROOM    HOTEL/MOTEL ROOM
  FLT/DY   FLIGHT PER DAY          SEAT    RESTAURANT SEAT
  PRKSPC   PARKING SPACE           STDNT   STUDENT
  PUMP     GAS(OR DIESEL) PUMP     STN     GAS(OR DIESEL) STATION

                                   17





                           TABLE 3, continued

                          VEHICLE TRIPS PER DAY
      LAND USE             TO & FROM LAND USE
      GENERATOR           (Rate/Unit as noted)         STATISTICS
 ------------------      ------------------------------------------------------
                                                           STD
                                                          ERROR # OBS.
     DESCRIPTION                                    STD    OF       IN
     & ITE CODE    UNITS    MEAN   MIN    MAX      DEV.   MEAN  SAMPLE

     OFFICE(700)

  Gen Off Bldg      1K SF  12.43   3.60   28.80    6.03    0.95    39
  710               EMP     3.54   2.42    6.22    1.16    0.24    23
                    ACRE  250.64  50.75  299.70 1580.16  116.03    25

  Urban             1K SF  10.33
                    EMP     2.94
                    ACRE  208.28

  Suburban          1K SF  14.81
                    EMP     4.22
                    ACRE  298.64

  Med Off Bldg      1K SF  39.83  38.68   42.55    2.74    1.94     2
  720               EMP    12.20  NA      NA      NA      NA        1
                    ACRE 6666.67  NA      NA      NA      NA        1
  Urban             1K SF  33.10
                    EMP    10.14
                    ACRE 5540.00
  Suburban          1K SF  47.46
                    EMP    14.54
                    ACRE 7943.34

  Gov Off Bldg      1K SF  67.72  NA      NA      NA      NA        1
  730               EMP    11.95  NA      NA      NA      NA        1
                    ACRE   66.25  NA      NA      NA      NA        1

  Urban             1K SF  56.28
                    EMP     9.93
                    ACRE   55.05

  Suburban          1K SF  80.69
                    EMP    14.24
                    ACRE   78.94

  Civic Center      1K SF  25.00  NA      NA      NA      NA        1
  740               EMP     6.09  NA      NA      NA      NA        1

  Off Parks         1K SF  20.65   9.40   30.30   11.68    6.74     3
  750               EMP     3.33   2.92    3.53    0.32    0.19     3
                    ACRE  276.38 153.68  340.87   93.86   54.19     3

  Urban             1K SF  17.16
                    EMP     2.77
                    ACRE  229.67
  Suburban          K SF   24.60
                    EMP     3.97
                    ACRE  329.31

                            LEGEND FOR UNITS:

  1K  SF   1,000 SQ. FT. GFA       CFL/DY  COMMERCIAL FLIGHT PER DAY
  ACRE     ACRE                    CIVEMP  CIVILIAN EMPLOYEE
  BED      HOSPITAL BED            DEFEMP  DEFENSE FORCES EMPLOYEE
  BOSBER   BOAT OR SHIP BERTH      DU      DWELLING UNIT

                                   18





                          TRIP GENERATION RATES


Click HERE for graphic.


                          Vehicle Trips Per...

  EMP      EMPLOYEE                ROOM    HOTEL/MOTEL ROOM
  FLT/DY   FLIGHT PER DAY          SEAT    RESTAURANT SEAT
  PRKSPC   PARKING SPACE           STDNT   STUDENT
  PUMP     GAS(OR DIESEL) PUMP     STN     GAS(OR DIESEL) STATION

                                   19





                           TABLE 3 , continued

                          VEHICLE TRIPS PER DAY
      LAND USE             TO & FROM LAND USE
      GENERATOR           (Rate/Unit as noted)         STATISTICS
 ------------------      -------------------------------------------------------

                                                           STD
                                                          ERROR # OBS.
     DESCRIPTION                                    STD    OF       IN
     & ITE CODE    UNITS    MEAN   MIN    MAX      DEV.   MEAN  SAMPLE

Research Cen        1K SF   5.34   1.78   12.98    4.02    1.42     8
  760               EMP     2.37   0.96    5.33    1.29    0.43     9
                    ACRE   57.25  15.61 1323.08  525.95  214.72     6

  Urban             1K SF   4.44
                    EMP     1.97
                    ACRE   47.57

  Suburban          1K SF   6.36
                    EMP     2.82
                    ACRE   68.21

Hi-Tech Off Bldg    1K SF   7.28   4.08    8.71    2.18    1.26     3
  770               EMP     2.76   2.39    3.27    0.47    0.27     3

  Urban             1K SF   6.05
                    EMP     2.29

  Suburban          1K SF   8.67
                    EMP     3.29

Twnhs Off Bldg      1K SF  23.47  19.06   24.78    4.94    2.85     3
  780

  Urban             1K SF  19.50

  Suburban          1K SF  27.96

  RETAIL(800)

Disc Shop Ctr       1K SF  70.13  25.53  106.88   27.83   10.52     7
  815               EMP    32.53  28.08   35.46    3.10    1.38     5
                    ACRE  456.31 127.64  480.63  302.57  135.31     5

Shp Ctr(<100k sf)   1K SF  83.43  18.10 270.89    45.47    5.29    74
  820,821           EMP    38.18  17.68   82.05   16.71    3.28    26
                    ACRE  786.72 303.55 2277.27  528.2599,83       28

Sh Ctr(100k.500k)   1K SF  49.64   2.80  116.14   22.26    1.84   146
  822,823,824,825   EMP    28.40  15.45   53.05   10.13    1.85    30
                    ACRE  462.40  46.94 1431.67 1268.74   40.06    45

Sh Cr(500k.1000k)   1K SF  34.44  10.30   61.18   11.38    1.42    64
  826               EMP    16.72   3.20   53.62   11.35    2.32    24
                    ACRE  405.22 119.10 1178.12 1251.48   51.33    24

Sh Ctr(>1000k sf)   1K SF  29.59  11.99   72.82   16.13    3.80    18
  827,828           EMP    12.50   6.14   42.41   14.60    5.16     8
                    ACRE  268.31  62.17 1259.74 1376.87  125.62     9

                            LEGEND FOR UNITS:

  1K SF    1,000 SQ. FT. GFA       CFL/DY  COMMERCIAL FLIGHT PER DAY
  ACRE     ACRE                    CIVEMP  CIVILIAN EMPLOYEE
  BED      HOSPITAL BED            DEFEMP  DEFENSE FORCES EMPLOYEE
  BOSBER   BOAT OR SHIP BERTH      DU      DWELLING UNIT

                                   20





                          TRIP GENERATION RATES


Click HERE for graphic.


                          Vehicle Trips Per...

  EMP      EMPLOYEE                ROOM    HOTEL/MOTEL ROOM
  FLT/DY   FLIGHT PER DAY          SEAT    RESTAURANT SEAT
  PRKSPC   PARKING SPACE           STDNT   STUDENT
  PUMP     GAS(OR DIESEL) PUMP     STN     GAS(OR DIESEL) STATION

                                   21





                           TABLE 3 , continued
                                 TABLE 3

                          VEHICLE TRIPS PER DAY
      LAND USE             TO & FROM LAND USE
      GENERATOR           (Rate/Unit as noted)         STATISTICS
 ------------------      -------------------------------------------------------
         STD
        ERROR     # OBS.
     DESCRIPTION    STD      OF    IN
     & ITE CODE    UNITS    MEAN   MIN    MAX      DEV.   MEAN  SAMPLE

  Qual StDwn Rest  SEAT    2.95    1.77    5.50    1.16    0.32    13
  831              1K SF  97.27   48.56  139.33   30.81    8.54    13
                   EMP    14.53    9.16   29.98    5.93    1.65    13
                   ACRE  478.44  223.21  806.32 1201.42   60.73    11

  Fast Food Restau SEAT   22.25    8.88   35.78    8.21    2.28    13
  833              1K SF 685.61  284.00  359.50  280.14   77.70    13
                   EMP    54.78   28.40   90.63   22.05    6.37    12
                   ACRE 2985.22 2772.22 3298.57  268.22  154.86     3

  New Car Sales    1K SF  47.52   15.45   79.00   36.15   20.87     3
  841              EMP    24.04   10.82   38.55   13.94    8.05     3
                   ACRE  385.57  162.25  526.67 1206.84  119.42     3

  Service Stations PUMP    *       *       *      NA      NA        *
  844              STN     *       *       *      NA      NA        *

  Food Store       1K SF   *       *       *      NA      NA        *
  850              ACRE    *       *       *      NA      NA        *

  Conv Market      1K SF 756.44  396.00 1438.00  334.23  118.17     8
  851              EMP   275.07  158.40  359.50   24.02   67.95     8
                   ACRE  289.70  221.33  419.50   74.37   33.26     5


  SERVICES(900)

  Walk-in-Bank     1K SF 169.00   NA      NA      NA      NA        1
  911              EMP    44.47   NA      NA      NA      NA        1
                   ACRE 1056.25   NA      NA      NA      NA        1

  Drive-in-Bank    1K SF 291.11  134.67 1520.00 1391.06  117.91    11
  912              EMP    79.79   31.85  380.00  101.75   30.68    11
                   ACRE  849.30  414.00 1647.50 1545.77  272.88     4

  Walk-in Sv & Ln  1K SF  61.00   NA      NA      NA      NA        1
  913              EMP    30.50   NA      NA      NA      NA        1
                   ACRE  261.42   NA      NA      NA      NA        1

  Drive-in Sv & Ln 1K SF  74.17   NA      NA      NA      NA        1
  914              EMP    49.44   NA      NA      NA      NA        1
                   ACRE 1483.33   NA      NA      NA      NA        1

                            LEGEND FOR UNITS:

  1K SF    1,000 SQ. PT. GFA       CFL/DY  COMMERCIAL FLIGHT PER DAY
  ACRE     ACRE                    CIVEMP  CIVILIAN EMPLOYEE
  BED      HOSPITAL BED            DEFEMP  DEFENSE FORCES EMPLOYEE
  BOSBER   BOAT OR SHIP BERTH      DU      DWELLING UNIT

                                   22





                          TRIP GENERATION RATES


Click HERE for graphic.


                          Vehicle Trips Per...

  EMP      EMPLOYEE                ROOM    HOTEL/MOTEL ROOM
  FLT/DY   FLIGHT PER DAY          SEAT    RESTAURANT SEAT
  PRKSPC   PARKING SPACE           STDNT   STUDENT
  PUMP     GAS(OR DIESEL) PUMP     STN     GAS(OR DIESEL) STATION

                                   23






Applicable Uses of Trip Rates

The most common use of trip rates is for site access studies.  A site
access study describes how traffic generated by either new land use(s)
or replacement land use(s) will be served by an existing or future road
network (50).  The analyses allow for the effect of site generated
traffic to be compared with the traffic on the adjacent road network. 
The site access study is being used more and more as a basis for
establishing a developer's share of roadway improvements and therefore
trip rates play a critical role in the process.

Many local jurisdictions are using trip rates as the basis for
assessments in local transportation improvement districts.  The design
hour volumes in the vicinity of sites can be forecast using Table 3 trip
rates for design of the roadway improvements.  Alternative land use
scenarios can be tested as part of site access studies, to determine the
optimization land density and mix with respect to traffic flow.  In some
cases, a reverse analysis can be conducted to determine the density and
mix of land uses that can be accommodated by a given roadway network
(50).

In addition to site access studies, Table 3 can also be used for
corridor and sub-area analyses (84).  Quick response techniques, both
manual and micro-computer, for transportation modelling have been
developed that can use peak hour or daily trip rates from Table 3 (6,
83).  Some techniques utilize highway networks in the trip
distribution/assignment procedure.  In these cases the trip rate data
for residential uses is converted into trip productions and trip
attractions as in the four step Urban Transportation Planning process.

Selection of Trip Rates

The weighted mean daily vehicle trip rates along with the minimum and
maximum trip rates measured in the sample are included in Table 3. The
weighted mean trip rates are presented for the peak hours (AM, PM and
peak hour of generator).  The weighted mean trip rates are recommended
for use by planners.  The standard deviation is provided for a measure
of how the individual trip rates in the sample are spread out from the
mean, A large standard deviation indicates that the individual trip
rates are distant from the mean trip rate.  The standard error of mean
helps to determine the potential degree of discrepancy between the
sample mean and the usually unknown population mean.  Deviations from
the mean trip rates may be dependent on the values of unknown variables
such as the extent of ridesharing, proximity to transit, or parking
costs.

                                   24





The selection of the appropriate time period of analysis is related to
the peak generation periods of the subject site and the adjacent street
traffic characteristics (5).  In general, the time periods selected
should result in the maximum impact of the site generated traffic on the
adjacent street traffic.  In most cases, the trip rates for the AM and
PM peak hours of the adjacent street traffic would be utilized for
conducting the site access studies and estimating roadway needs.  Some
sites such as shopping centers have a considerable impact during the PM
peak hour of the adjacent street system, but may have an even greater
impact during the evening hours or on Saturdays.  Therefore, in such
cases the generator may have to be analyzed for all three time periods
(PM peak hour e.g. 5-6 PM Friday; evening peak hour e.g. 7-8 PM Friday;
Saturday peak hour e.g. 1 to 2 PM Saturday) to determine the design
requirements and the impact on the adjacent street traffic flow (5).

Selection of Independent Variable

Trip rates for land use generators in Table 3 are presented for more
than one independent variable.  In each case, the recommended
independent variable is listed first.  This independent variable is
recommended based on the sample size, the general data availability and
the correlation between trips and the independent variable.

Selection of the independent variable is critical for determining the
total trips generated.  Consider for example, an office building while
the number of employees is an excellent indicator of trip rates.  This
information is generally not available.  Further more, the number of
employees may change over time due to new tenants or change in tenant
mix.  Therefore, gross building area is listed as the first choice in
Table 3. The S.I.T.E. Handbook presents a discussion on the office trip
generation rate including the square feet per employee typically found
in office buildings.  The other independent variable presented in Table
3 is acres.  This information is generally available.  Due to the
variations in floor area ratio or buildable area, correlation between
trips and acres is not as good as that between trips and employees or
gross building area.

In some cases (generally, in the planning stage), only the parcel size
is known.  In these cases, common land use densities can be used to
determine an estimate of the independent variable with a higher
correlation trip rates.  For industrial uses, employee densities per
acre of land and trip rates per employee may be utilized.  For shopping
centers and office buildings,

                                   25





building density can be estimated from parcel size using the Floor Area
Ratio, and the trip rate per 1000 gross square feet can be utilized. 
For residential uses, the applicable zoning code can be used to
determine the number of dwelling units per acre of land.  Table 4
presents some land use densities (5).

Application of Adjustment Factors

Adjustment factors for residential characteristics (household size,
vehicle ownership and density) are presented in Table 3a.  The
adjustment factors are to be added (or subtracted) from the daily trip
rates with dwelling units as the independent variable.  Furthermore, any
combination of adjustment factors may be applied.  If specific
residential characteristic data are unavailable, then the mean trip rate
should be utilized.  The. application of adjustment factors to peak hour
trip rates, requires the computation of the ratio of the daily adjusted
trip rate to daily mean trip rate.  The procedure is illustrated in
Table 5.

                                   26





                                TABLE 3a
           ADJUSTMENT FACTORS FOR RESIDENTIAL CHARACTERISTICS


Click HERE for graphic.

___________________________

    (1) Adjustment factors to be added (or subtracted) from the mean
        daily trip rate per dwelling unit.





                                 TABLE 4
                       TYPICAL LAND-USE DENSITIES

       Land Use                      Density

110 General Light Industrial  16.4 employees per acre
                              1.7 employees per T.G.S.F.

120 General Heavy Industrial  7.6 employees per acre
                              1.6 employees per T.G.S.F.

130 Industrial Park           18.0  employees  per  acre
                              2.0 employees per T.G.S.F.

140 Manufacturing             18.5  employees  per  acre
                              1.9 employees per T.G.S.F.

150  Warehouse                14.0 employees per acre
                              1.25 employees per T.G.S.F.

711  General Office,
     Under 100 T.G.S.F        4.7 employees per T.G.S.F.

712  General Office,
     100-199.9 T.G.S.F.       4.2 employees per T.G.S.F.

713  General Officer
     Over 200 T.G.S.F.        3.1  employees per T.G.S.F.

720   Medical Office Building 3.7 employees  per  T.G.S.F.

770  High Tech Electronics    40-100 employees  per  acre

814-828 Retail Center         10-14  T.G.L.S.F. per acre


NOTE: T.G.S.F.  = thousand gross square feet;
      T.G.L.S.F. = thousand gross leasable square feet.

SOURCE:    Reference (5)
           Reported with permission from ITE.

                                      28





                                    TABLE 5
                       APPLICATION OF ADJUSTMENT FACTORS


PROBLEM:
Determine daily and PM peak hour trip rates per dwelling unit for a proposed
single family detached housing development located in a suburban area.
  Residential density                       = 3.5 d.u./acre
  Average household size                    = 2.5 persons
  Average vehicle ownership per household   = 2.5
SOLUTION:
Mean Daily Trip Rate
Refer to Table 3 for trip rates by land use type
  Land use generator "single family detached" (210).
  Daily trip rate/d.u. in the suburban area   =  10.03

Adjustment Factors for Mean Daily Trip Rate
Refer to Table 3a for adjustment factors due to residential characteristics.

  Household Size (2.5)            =   1.8
  Vehicle Ownership (2.5)         = + 2.9
  Density (3.5 d.u./acre)         =   0.0
  -------------------------------   --------
  Current time adjustment factor  = + 1.1

  Adjusted daily trip rate   = 10.03 + 1.1  = 11.13 trips/d.u.

PM Peak Hour Trip Rate
  Adjustment factor for PM peak hour adjusted daily trip rate for suburban
  location  = 11.13/10.03 =  1.11
  mean daily trip rate for suburban location

  The AM peak hour trip rates. if desired, should also be factored by this
  adjustment factor.

Refer to Table 3. Land Use 210. for PM Peak Hour Inbound/Outbound/Total vehicle
trip rates.

    PM peak hour trip rates/d.u.

    In      = 0.64 x 1.11 =  0.71 trips/d.u
    Out     = 0.36 x 1.11 =  0.40 trips/d.u.
    Total   = 1.00 x 1.11 =  1.11 trips/d.u.

                                      29





IV. OTHER FACTORS AFFECTING TRIP RATES

The previous chapter presented updated trip rates for a wide range of
land uses; including the development and application of adjustment
factors for residential use.

In addition to the application of the trip rate process to individual
land uses, there are two other conditions which require trip rate
adjustments.

   -  Multi-use developments (MUD) which consist of a complimentary mix
      of land uses but for which individual land use trip rates cannot
      be simply added without adjustment.
   -  Development located along major travel corridors where current
      pass-by traffic will be 'captured' by the new land use.  A
      straightforward application of Table 3 will make the trips rates
      too high.

MULTI-USE DEVELOPMENT

A Multi-Use Development (MUD) may be described as a concentration of
compatible land uses which are physically integrated by means of
internal pedestrian or roadway network system.  The multi-use
development was initially a concept of private developers who were aware
of its market potential.  They were also influenced by public planning
agencies which became aware of the need to encourage Planned Unit
Development (PUD).  A PUD is usually defined as a variety of land use
types with a predominance of residential development.  A PUD by
definition is different from a multi-use development (MUD) which
consists of more retail and office uses Because MUD/PUD land use
components tend to complement each other, it reduces the need for
persons to make vehicular trips beyond the development.  The composition
of a MUD/PUD determines the amount of interaction among its land use
components.  The trips on the roadway network, external to the
development,  vary depending on the mix of land uses within the
development.  Two studies on PUDs have been conducted recently (70,92). 
Both PUDs were located in suburban areas.  

One PUD consisted of a total of 2,330 residential units including 1,138
single family detached units, 1000 townhouses and 192 garden apartments.
(See Figure 1).  Also included is the PUD were the following land uses:
   -  two elementary schools
   -  a middle school
   -  a day care center

                                   30





                                FIGURE 1
                          NORTHERN VIRGINIA PUD


Click HERE for graphic.


                                   31





    -   9,000 square feet of retail area with a convenience store,
        beauty salon, florist, dry cleaner, a restaurant and a bank.
    -   six pump self-service gas stations fire and rescue station
    -   community center with a swimming pool

Based on the ground count data for this PUD, it was estimated that
approximately 28 percent of the residential trips occur within the
development as internal trips.  This leaves only 72 percent of the trips
generated by the residential units within the PUD impact the external
roadway network.

Another study analyzed external trips generated by uses in a PUD
(located in Richmond, Virginia) utilizing home interview surveys,
roadside origin-destination surveys, ground counts and turning movement
counts (70).  This PUD, illustrated in Figure 1. contains approximately
2300 occupied dwelling units.  A vast majority are single family
detached units with some multi-family townhouse type units.  There are
two primary areas of commercial development.  The following land uses
are located in the Richmond PUD:
    -   85,000 gross square feet of primary commercial center with a
        grocery store, a drive-in savings and loan, a convenience food
        mart, a drug store, several small offices and a variety of
        small-shops
    -   16,600 gross square feet of medical center a small computer
        store
    -   63,000 square feet of business park
    -   recreational facilities including a golf courser tennis courts,
        swimming facilities and several lakeside recreational facilities

Table 6 presents an estimate of the number of external trips generated
by residential and commercial uses in the PUD.  The percentage of
external trips varies between 30 percent and 65 percent depending on the
use and time period considered.  The residential uses resulted in 50
percent daily external trips; however, these percentages may vary
depending on the quantity of commercial use in the PUD.  A development
with little or no commercial use may be 10 percent higher, whereas, a
development with more commercial use may be 5 percent lower (70).  More
data are necessary to verify these estimates.

Figure 3 presents relationships between percentage of internal trips and
the composition of a PUD based on one study (70).  Curve A relates the
percentage of internal home-based work trips to a ratio between office
area (in gross square feet) and the number of residential units.

                                   32





                                FIGURE 2
                         RICHMOND, VIRGINIA PUD


Click HERE for graphic.


                                   33





                                TABLE 6 :
                EXTERNAL TRIPS GENERATED BY USES IN A PUD


Click HERE for graphic.

___________________________

    (1) Rates are for street peak hours (7-8 AM and 4-6 PM).  Peak hours
        of generator closely coincide with peak hours of adjacent street
        traffic.

    (2) External percentages for residential development may vary
        depending on quantity of commercial use in PUD.

    (3) Estimated based on student population and trip purpose data from
        residential survey.

    (4) Not available.  Number of daily trips was approximated for this
        use, based on ratio of peak to daily from other sources.

    (5) Percent external for office based on employee surveys and does
        not include visitors.

    (6) School trip rate based on no. students.

    (7) Daily external % for non-residential uses based on weighted
        average of midday and peak period results

    Source:  Reference (70)

                                   34





                                FIGURE 3
            ILLUSTRATIVE RELATIONSHIP BETWEEN PERCENTAGES OF
              INTERNAL TRIPS AND RATIO OF COMMERCIAL SPACE
                     TO NUMBER OF RESIDENTIAL UNITS


Click HERE for graphic.


    NOTE:   Relationships are approximated based on one PUD data.  More
            data necessary before relationships can be widely applied. 
            These relationships should be reasonably applicable to PUDs
            not exceeding 3000 to 4000 residential units.

    SOURCE: Reference (70)

                                   35





Curve B relates internal home-based non work trips to a ratio of
commercial area and the number of residential units.  It should be noted
that both curves are approximate, but should be generally applicable to
PUDs not exceeding 3000 to 4000 residential units.

SITE DEVELOPMENT CAPTURE RATES FOR PASS-BY TRAFFIC

Site access studies generally assume that all trips to the new
development are new trips which were not made prior to the development
being completed.  This is incorrect since a portion of the new trips are
already being made to other similar and existing developments.  In this
case a route diversion occurs.

A second assumption for site access studies is that all of the trips are
primary trips being made for a specific purpose; to return directly to
their place of origin.  Several land use generators such as shopping
centers, drive-in (fast food) restaurants, service stations, convenience
markets and other support services (banks, etc.), capture trips from the
normal traffic passing-by the site.  For many of these trips, the stop
at the site is a secondary part of a linked trip such as from work to
shopping center to home. in all of these cases, the driveway volumes at
the site are higher than the actual amount of traffic added to the
adjacent street system, since some of the site generated traffic was
already counted in the adjacent street traffic.  Table 7 presents the
limited information available on the capture rates for pass-by traffic. 
In the case of shopping centers, the trip rates from Table 3 can be
reduced by 25 percent (from Table 7) to determine the actual traffic to
be added to the adjacent street network: the total driveway volumes as
well as the traffic on the internal roadway network should be based on
Table 3 rates without any reduction due to capture rates.  Information
on trips "diverted' from a nearby roadway based on one study are also
presented in Table 7. The results in Table 7 should be used cautiously
since they are based on a limited number of studies.

Since MUD or PUD developments may include various modes of travel, the
user may also wish to refer to the ITE publication 'Using the ITE Trip
Generation Report(s)" for methodologies for adjusting trip rates to
reflect the use of alternative modes of transportation (5) .

                                   36





                                 TABLE 7
            SITE DEVELOPED CAPTURE RATE FROM PASS-BY TRAFFIC

                                 PERCENT OF SITE TRAFFIC
  Land Use                 Primary    From Pass-by    Diverted From
                            Trips        Traffic      Another Route
                             [2]                           [3]
  ---------------          ------        ------          ------
  820-828 Shopping           35%           25%             40%
          Centers

  833 Fast Food Restaurant   45%           [1]             [1]

  844 Service Station      26% [4]         58%           16% [4]

  851 Convenience Market     [1]           45%             [1]


SOURCE: Reference (5), except as noted
        Reprinted with permission from ITE.

    [1] Not measured
    [2] These are trips that were made for a-specific purpose and
        returned directly to their place of origin.
    [3] These are trips in which the stop at the site land use is part
        of the current sequence of stops.  This involves trip chaining
        of a series of trip times.  Furthermore the stop requires a
        significant route diversion from the route that would be
        followed otherwise, if this particular stop were not made.
    [4] Source: Reference (49)

                                   37





An extensive literature review and data collection effort was carried
out as part of the study.  A detailed work plan was developed to analyze
the data collected including the development of trip rate adjustment
factors for site location availability of transit and vehicle occupancy. 
However, data on these factors were generally missing from the data
base.  In some cases where data was available, the sample size was not
large enough to conduct statistical tests.  Trip rates by location were
developed for land uses with adequate samples.  For residential uses,
trip rate adjustment factors were developed for certain residential
characteristics.  In order to fill the data gaps, recommendations for
further research are presented in Appendix C.

                                   38





                               REFERENCES

 1.   Albuquerque Metropolitan Transportation Planning Program "A
      Procedure for Determining Future Trip Ends", January, 1968.

 2.   Arizona Department of Transportation, "Trip Generation Intensity
      Factors", Phoenix, Arizona, July, 1976

 3.   Barret, R. "Trip Generation and Modal Split of Shopping Centers".
      Traffic Engineering and Control. February, 1975.

 4.   Brog, Werner, et al.  "Problems of Non-reported Trips in Surveys
      of Non-home Activity Patterns".  TRR 891, TRB, Washington, D.C.

 5.   Buttke, Carl H., "Using the ITE Trip Generation Report". Prepared
      for Institute of Transportation Engineers. July, 1984.  ITE,
      Washington, D.C.

 6.   Comsis Corporation, "Quick Response System (QRS) Documentation."
      Prepared for U.S. Department of Transportation.  January 1984

 7.   California Department of Public Works - District 4, Second
      Progress Report on Trip Ends Generation Research Counts, San
      Francisco, California, December, 1966.

 8.   California Department of Public Works - Division 4, Seventh
      Progress Report on Trip Ends Generation Research Counts, San
      Francisco, California, December, 1971.

 9.   California Department of Public Works - Division 4, Third
      Progress Report on Trip Ends Generation, Research Counts, San
      Francisco, California, December, 1967.

10.   California Department of Public Works, Division 4, Trip Ends
      Generation Manual, San Francisco, California, May 1971.

11.   California Department of Transportation - District 4, Fourteenth
      Progress Report on Trip Ends Generation Research Counts, San
      Francisco, California, July 1982.

12.   California Department of Transportation, "The 1976 - 1980
      Statewide Travel Survey", December, 1981.

                                   39





13.   California Division of Highways , Sixth Progress Report on Trip
      Ends Generation Research Counts, San Francisco, California,
      December, 1970.

14.   Cambridge Systematics, Inc., "The Development of Home-Base Trip
      Production Models and their Comparison with 1978 Data (Technical
      Memorandum), Cambridge, Mass., 1979.

15.   Chicago Area Transportation Study,, "An Accessibility Sensitive
      Trip Generation Model", October, 1971.

16.   Chicago Area Transportation Study, Travel Forecasting Process,
      Chicago, Illinois, April, 1979.

17.   Chicago Area Transportation Study (CATS), "Trip Generation Rates
      for Multiple Family Residential Developments and Neighborhood
      Shopping Center in the Chicago Area," December, 1982.

18.   City of Los Angeles, "Composite Report of Traffic Generation
      Studies".  August, 1969.

19.   Cirgin, M. "Trip Generation Rates of Multiple Family Residential
      Developments and Neighborhood Shopping Centers in the Chicago
      Area".  Chicago Area Transportation Study?  Chicago, Illinois,
      December, 1982.

20.   The Comprehensive Planning Organization of the San Diego Region? 
      Travel Behavior Survey, San Diego, September, 1978.

21.   Connecticut Department of Transportation, "Analysis of Survey
      Responses to the 1976 - 1977 Connecticut statewide Household
      Travel Survey", Wethersfield, Connecticut.

22.   Connecticut Department of Transportation, "Trip Generation",
      Wethersfield, Connecticut, November, 1980.

23.   Delaware Division of Highways, "Special Traffic Generation
      Survey" Bureau of Highway Planning, March. 1970 September, 1972.

24.   Delaware Department of Highways and Transportation.  Special
      Traffic Generator Study: Report 1, Residential Generation, 1974.

                                   40





25.   Delaware Department of Highways and Transportation Special
      Traffic Generator Study: Report 2, Industrial Generations, 1973.

26.   Delaware Department of Highways and Transportation, Special
      Traffic Generator Study: Report 4, Commercial Generations, 1975.

27.   Delaware Valley Regional Planning Commission, "Trip Generation
      Analysis, Regional Shopping Malls", June, 1983.

28.   Deutschman, Harold D. "Establishing a Statistical Criterion for
      Selecting Trip Generation Procedures".  Presented at 46th Annual
      Meeting, HRB, Washington, D.C., January, 1967.

29.   East-West Gateway Coordinating Council, "1975 Trip Generation
      Study for the Saint Louis Area", June, 1975.

30.   Federal Highway Administration, "1977 Nationwide Personal
      Transportation Study", Report Number's 4, 7 and 9, U.S.
      Department of Transportation, Washington, D.C.

31.   Federal Highway Administration, "The Baltimore Travel Demand Data
      Set - User's Guide", December, 1980

32.   Federal Highway Administration, Traffic Volume Trends Monthly.

33.   Fogarty, William, J. "Trip Production Forecasting Models for
      Urban Areas".  Transportation Engineering Journal, November,
      1976.

34.   Fleet, C. R., and Sosslau, A. B., "Trip Generation Procedures: An
      Improved Design for Today's Needs". Traffic Engineering: Volume
      46, November, 1976.

35.   Greenbaum, D. W. "Traffic Engineering Findings are often
      Deceptive", ITE Journal, July, 1982.

36.   Gur, Yehuda, "An Accessibility Sensitive Trip Generation Model",
      Chicago Area Transportation Study, October, 1971.

37.   Highway Research Board, "Developing Transportation Plans", HRB
      240, Washington, D.C., 1968.

                                   41





38.   Highway Research Board, "Forecasting Highway Trips", ERB Bulletin
      297, Washington, D.C., October, 1961.

39.   Highway Research Board, " Urban Travel Patterns for Airports,
      Shopping Centers, and Industrial Plants";  NCHRP Report 24,
      Washington, D.C., 1966.

40.   Highway Research Board, "Transportation Forecasting", HRB 472,
      Washington, D.C., 1973.

41.   Highway Research Board, "Travel Characteristics in Urban Areas",
      HRB Bulletin 203, National Research Council, Washington, D.C.,
      1958.

42.   Highway Research Board, "Urban Transportation - Demand and
      Coordination, HRB Bulletin 326, Washington, D.C., 1962.

43.   Holden Jr., Allen et al.  "Trip Generation - The San Diego
      Experience".  ITE Journal - California Border Section. January,
      1983.

44.   ITE Technical Council Committee 6F-12, "Consistency of Origin-
      Destination Characteristics Through Time", Journal, Volume 49,
      Virginia, October, 1979.

45.   Institute of Transportation Engineers, Trip Generation An
      Informational Report.  ITE, Washington, D.C., 1982.

46.   Jefferies, W. and Carter, E. C. "Simplified Techniques for
      Developing Transportation Plans".  Presented at 47th Annual
      Meeting, HRB, Washington, D.C., January, 1968.

47.   JHK & Associates, "Trip Generation Study for Prince George's
      County", February, 1984.

48.   JHK & Associates, "Silver Spring Metro - Before and After Study",
      January, 1979.

49.   Kellerco Data Files - Unpublished.

50.   Kellerco, Inc., "Site Impact Traffic Evaluation (SITE) Handbook",
      Prepared for Federal Highway Administration, January, 1985.

51.   Kimley - Horn and Associates, Inc., "Update Study of Vehicular
      Traffic Generation Characteristics Within Palm Beach County".
      (Unpublished), West Palm Beach, Florida, 1975.

                                   42





52.   Kimley - Horn and Associates, Inc.j, "Use of Private Funds for
      Highway Improvements." Final Report prepared for Federal Highway
      Administration, January, 1984.

53.   Kimley - Horn and Associates, Inc., "Vehicular Traffic Generation
      Characteristics-Within Palm Beach, Florida, 1972.

54.   Kollo, Hanna P. H., and Purvis, C. L., "Changes in Regional
      Travel Characteristics in the San Francisco Bay Area: 1960-1981",
      TRB Annual Meeting, Washington, D.C., January, 1984.

55.   Kwantes, Peter W., "Transportation Aspects of Multi-Use Centers". 
      Traffic Quarterly.  October, 1972.

56.   Lopata, R. H. and S. S. Jaffe, "Fast Food Restaurants Trip
      Generation, Another Look", ITE Journal, April, 1980.

57.   Levinson, H. S. and Wynn, F., "Some Aspects of Future
      Transportation in Urban Areas".  HRB 376., Washington, D.C.

58.   Maryland Department of Transportation, "Trip Generation Study",
      Glen Burnie, Maryland, 1976.

59.   Maryland State Roads Commission, "Trip Generation Study 1968". 
      Glen Burnie, Maryland, 1968.

60.   Maryland State Roads Commission, "Trip Generation Study 1970",
      Glen Burnie, Maryland, 1970.

61.   Memmott, Frederick W., et al.  "Predicting Future Demand for
      Urban Area Transportation".  HRB Bulletin 326.  Washington, D.C.

62.   Metropolitan Washington Council of Governments, Trip Generation
      Rates, Washington, D.C., November, 1983.

63.   Metropolitan Washington Council of Governments Trip Generation
      Data.  Unpublished.

64.   New Hampshire Department of Public Works and Highways, "Traffic
      and Trip Generation Characteristics of New Hampshire Shopping
      Centers", Planning and Economics Division, January, 1977.


                                   43





65.   New York State Department of Transportation, Travel Cycle
      Characteristics of Highway Travel Households.  Report 15. 
      August, 1982.

66.   New York state Department of Transportation, An Update Household
      Reported Trip Generation Rates, Report 31, Planning Division,
      August, 1983.

67.   Ohio - Kentucky - Indiana Regional Council of Governments, Long
      Range Plan, Cincinnati, Ohio, November, 1983.

68.   Pas, Eric, I. "An Empirical Comparison of Zonal, Household and
      Personal Models of Home-Based Trip Generation". Traffic
      Engineering and Control.  Volume: 19, 1978.

69.   Reid, Fred A. "Critique of ITE Trip Generation Rates and an
      Alternative Basis for Estimating New Area Traffic. TRB 874. 
      Washington, D.C., 1982.

70.   Richmond Regional Planning District Commission, "Planned
      Community External-Internal and Internal-Internal Traffic
      Generation Study", Richmond, Virginia, June, 1984.

71.   Roads and Transportation Association of Canada, "A Review of Trip
      Generation Analysis Procedures Used In Canadian Urban
      Transportation Planning Studies", Technical Publication Number 4,
      Toronto, 1974.

72.   Ruiter, Earl R. "The Development of Home-based Trip Production
      Models and their Comparison with 1978 Data", Cambridge
      Systematics, Inc., October, 1979.

73.   Sachdev, Labh S. and Leonhardt, Karlfritt, "Trip Generation
      Update", Puget Sound Governmental Conference, 1972.

74.   San Diego Association of Governments, "San Diego Traffic
      Generators", May, 1979.

75.   Southwestern Pennsylvania Regional Planning Commission, "Person
      Trip Production Rates per Household". Unpublished.

76.   SPSS Inc.  SPSS User's, Guide, McGraw-Hill Book Company, New
      York, 1983.

 77.  Sterns, M.D. "Social Impacts of the Energy Shortage Behavior and
      Attitude Shift".

                                   44


 


92.   Virginia Highway and Transportation Research Council "Residential
      Trip Generation in Northern Virginia". Unpublished.

93.   Virginia Highway & Transportation Research Council, "Special Land
      Use Trip Generation at Special Sites", January, 1984.

94.   West Virginia Department of Transportation, "Trip Generation
      Rates", Unpublished. 

95.   Zevin, I., Trip Generation Study of Various Land Uses.
      Connecticut Department of Transportation: June, 1974.

96.   Zevin, I., Trip Generation Study of Various Land Uses. Supplement
      A. Connecticut Department of Transportation: March, 1975.

                                   46





                               APPENDIX A
                       LIST OF AGENCIES CONTACTED

 1.   Washington Council of Governments,
      Washington, D.C.

 2.   Southwestern Pennsylvania Regional Planning Commission
      Pittsburgh, Pennsylvania

 3.   Metropolitan Transportation Commission, San Francisco, California

 4.   Southeast Michigan Council of Governments, Detroit, Michigan

 5.   Ohio-Kentucky-Indiana Council of Governments, Cincinnati, Ohio

 6.   Chicago Area Transportation Study, Chicago, Illinois

 7.   CALTRANS, California

 8.   Maryland Department of Transportation

 9.   Connecticut Department of Transportation

10.   Delaware Department of Transportation

11.   Arizona Department of Transportation

12.   Virginia Department of Highways and Transportation

13.   San Diego Association of Governments

14.   Virginia Highway and Transportation Research Council

15.   Maryland National Capital Park and Planning Commission

16.   District of Columbia Department of Public Works

17.   Fairfax County, Virginia

18.   Prince George's County, Maryland

19.   Anne Arundel County., Maryland

20.   Baltimore Regional Planning Commission

                                   A-1





21.   Transportation Research Board

22.   Montgomery County, Maryland

23.   Delaware Valley Regional Planning Commission

24.   Metropolitan Government of Nashville and Davidson County,     
      Tennessee

25.   City of Pittsburgh, Pennsylvania

                                   A-2





                               APPENDIX B
                     TRIP RATE ANALYSIS METHODOLOGY

DATA SOURCES

An extensive literature review was performed to identify relevant trip
generation (rate) data.  This literature review included direct contacts
with state and local agencies, a TRIS computerized reference search, and
review of U.S. Department of Transportation and University of Maryland
library information.  Initially, an extensive list of references
pertaining to trip rates was developed.  In addition, the TRIS
computerized search revealed 497 references.  The reference list was
then screened for relevancy to this study and a selected number of
references were obtained and reviewed.  In addition to the library
search, a number of state and local agencies responsible for
transportation planning were contacted.  The agencies contacted are
shown in Appendix A. Several of these agencies were able to provide
reports or data summaries pertaining to trip generation rates.

The data sources included data from home interview survey's as well as
driveway counts collected within the last five years and represent the
current socioeconomic conditions and the post 1973 energy crisis travel
behavior.' The data sources on driveway counts included land uses such
as single family and multi-family residential; high-technology,
townhouse and general office buildings; industrial plants; shopping
centers of different sizes; hotels; hospitals and clinics; fast food
restaurants; and miscellaneous services such as banks, beauty salons,
dry cleaners, and printing shops.  Some sources include data for peak
hours and daily trips, others include data for peak hours or daily
trips.  In most of the cases,, the location of the site within the
Standard Metropolitan Statistical Area (SMSA) was identified.  The home
interview surveys provide travel data for all members of the household
for a given day.  For each trip made, travel data collected through home
interviews generally include: type of vehicle, trip origin and
destination vehicle occupancy, trip purpose and time of trip origin.  In
addition to the travel data, household data, such as location, number of
persons in the household, number of licensed drivers, household income
range, number of vehicles and type of housing structure are also
collected.  In this study, the home interview data was used to study the
impact of residential characteristics on trip generation rates.

For residential uses, location data as well as residential
characteristics (household size, vehicle ownership and density) data
were available for several samples located in the suburban

                                   B-1





areas.  However, residential characteristics data for other locations
(urban and rural) were generally not available. other residential
characteristics, such as rent, value of dwelling, and number of workers
in the household were generally not available in the ground count data
base.  These characteristics were available from home interview surveys
such as from Detroit and Baltimore.  Efforts to correlate ground count
data from these cities to the home interview survey were not successful
due to lack of ground count data for the matching locations.

METHODOLOGY

Trip rate analyses were also conducted on the following:
    1)  determining the effects of older data in the ITE data base;
    2)  residential trip rate analysis as a function of residential
        characteristics.

Effects of Older Data

Much of the data for the existing trip generation rates including the
ITE data base date back to 1960. over the period of twenty years from
1960 to 1980 several changes have occurred that may have changed the
vehicle trip rates.  In 1973-74 a serious energy crisis occurred.  This
crisis resulted in severe shortfalls in gasoline as well as significant
increases in gasoline prices.  During the energy crisis period, the
increase in transportation costs and the energy constraints resulted in
a reduction in vehicular travel and changes in travel patterns such as
increased ridesharing and trip chaining.

The ITE data base, augmented by the data collected in this study, was
used to determine the effects of older data.  The data base was split
into two groups: (1) pre-1973; and (2) post-1973 based on the assumption
that the 1973 energy crisis was the major reason for the changes in
travel behavior and the associated changes in trip rates.  Based on data
availability, and the frequency of use of data, the following land uses
were analyzed:

    -   Industrial/manufacturing - general light industrial, heavy
        industrial, industrial park, manufacturing and warehousing.
    -   Residential - single family, apartment (low-rise and high-rise)
        and planned unit developments.
    -   Hotel
    -   Hospital
    -   Offices - general, medical office building, office park and
        research center.

                                   B-2





    -   Shopping Center - regional, community neighborhood and central
        area, and quality restaurant.
    -   Drive-in bank

Trip generation rates (simple arithmetic means) for pre-1973 and post-
1973 groups were estimated using the Statistical Package for Social
Sciences (SPSS) Version 9. The mean trip rates from the two groups were
compared to determine significant .differences using student "T" test
and "F" ratios.  Analysis of Variance (ANOVA) was used to test
significance of differences between group means.  If the group means are
not significantly different, then the pre-1973 data would be usable
under today's conditions.  If the test fails - that is, if the means are
found to be significantly different, then the pre-1973 data would not
represent the current travel behavior.

Table B-1 presents the results of the tests of significant differences
between the pre-1973 and post-1973 data for selected land uses.  For
each land user the number of cases, mean daily trip rate and standard
deviation are presented for the pre-1973 and post-1973 conditions.  It
should be noted that the mean trip rates are simple arithmetic means. 
The student "T" values, as computed, are presented along with the values
from "T" tables for the 5 percent and 1 percent level of significance on
the basis of a two-tailed test.  It should be noted that for some land
uses, sample sizes were not sufficient to perform meaningful T-tests. 
In all cases? based on the T-tests, it can be concluded that there is
not significant difference between the two means at a 1 percent level of
significance.  On the basis of a two-tailed test at a 5 percent level of
significance, the mean trip rates for all land uses, except apartments
are not significantly different.  For the apartments, since the
differences between means are significant at the 5 percent level but not
at the 1 percent level, it can be concluded that the means are probably
different.

For some land uses, such as industrial parks and hospitals, the mean
trip rates for the post-1973 data were intuitively different than the
pre-1973 data.  In these cases, the F-value was computed and compared
with the tabular values for the F-distribution.  A 5 percent
significance level was selected for comparison with the computed values. 
If the computed F is larger than the value reported in the F table, the
null hypothesis that the means are equal can be rejected. if it is
smaller, the null hypothesis cannot be rejected. In all cases analyzed,
the computed F value was smaller than the table value.  The null
hypothesis that the means are equal cannot be rejected.  This analysis
indicated that the trip rate means between the pre-1973 and post-1973
period were not significantly different.

                                   B-3





                                TABLE B-1
    TEST OF SIGNIFICANT DIFFERENCES BETWEEN PRE-1973 AND POST-1973 DATA


Click HERE for graphic.


    NOTE:  NA  -  Not Applicable

                                   B-4





                                TABLE B-2
      TEST OF SIGNIFICANT DIFFERENCES BY LOCATION BETWEEN PRE-1973
                           AND POST-1973 DATA


Click HERE for graphic.


    NOTE:   NA - Not Applicable

                                   B-5





Further tests were conducted for some land uses to verify the
differences between the means based on location of the land use within
an SMSA.  The results are presented in Table B-2 in a similar format as
Table B-1.  T-tests and F-tests were conducted for each of the land uses
listed.  The results showed that the mean trip rates for the pre-1973
and post-1973 time periods were not significantly different by location
within an SMSA.

These analyses showed that the mean-trip rates for the older data (pre-
1973) were not significantly different than the newer data (post-1973). 
Therefore, it was decided to include the pre 1973 data in the updating
of the trip generation rates.

Residential Analysis

The impact of residential characteristics on trip generation rates was
estimated using the updated ITE data base, as well as the home interview
survey data.  The ITE data base includes residential characteristics
such as household size, household income, residential density, vehicle
ownership and location.  A cross-classification analysis of the
variables was carried out to determine the sample sizes in each cell. 
This analysis found that an insufficient number of observations existed
to study the income data, as well as all locations other than suburban
areas.  Accordingly, a multiple regression analysis was conducted with
daily vehicle trips per dwelling unit as the dependent variable and
household size, vehicle ownership and residential density as the
independent variables.  Three residential land uses were analyzed:
single family detached, apartments and condominiums.  The results of the
analyses are presented in Table B-3, along with associated statistics. 
As noted in the table, the correlation coefficients are greater than 0.9
in all cases.  These regression relationships were utilized in
developing trip rate adjustment factors for the three residential land
uses.

In addition to the regression analysis, cross-classification of trip
rate data from other sources was carried out.  The Arizona Department of
Transportation conducted a study on the value of dwellings as a
residential characteristic of trip rates (2).  The trip rate summary for
three areas in the U.S. (Delaware, Wisconsin and Ohio) are presented in
Table B-4.  The weighted average trip rate for low value single family
dwelling (less than $250,000 in 1976 dollars) is 9.96.  The trip rates
increase as the market value of the dwelling increases (11.09 for market
values between $25,000 and $50,000 and 14.72 for market value over
$50,000).  A two-tailed T-test test indicated that the means were
significantly different at the 5 percent level of significance.

                                   B-6





                                TABLE B-3
                      MULTIPLE REGRESSION ANALYSIS
                     STATISTICS FOR RESIDENTIAL USES

SINGLE FAMILY RESIDENTIAL    DETACHED

  Multiple R         .98087  Analysis of Variance
  R Square           .96210             DF  Sum of Squares Mean Square
  Adjusted R Square  .96027  Regression  3    5577.62697    1859.20899
  Standard Error    1.88251  Residual   62     219.71817       3.54384

                             F = 524.63098            Signif F = .0000

VARIABLES IN THE EQUATION

Dependent Variable - Trip Rate Per Dwelling Unit
    Variable            B          SE B            BETA   T    SIG T

    Household Size      1.55       .35206        .55420   4.043.0001
    Vehicle Ownership   2.93       .81953        .43579   3.333.0015
    Density            -0.14       .08642       -.00600   -.149.8820

 APARTMENTS

 Multiple R         .96831 Analysis of Variance
 R Square           .93762              DF  Sum of Squares Mean Square
 Adjusted R Square  .93337 Regression    3    1929.41209     643.13736
 Standard Error    1.70797 Residual     44     128.35441       2.91715

                             F = 220.46803            Signif F = .0000

VARIABLES IN THE EQUATION

Dependent Variable - Trip Rate Per Dwelling Unit

    Variable            B          SE B            BETA   T    SIG T

    Household Size      1.93       .68199        .64271   2.959.0050
    Density             0.03       .02292        .09882   1.207.2339
    Vehicle Ownership   1.10       1.16138       .24229   .991 .3269

  CONDOMINIUMS

 Multiple R         .96166 Analysis of Variance
 R. Square          .92478              DF  Sum of Squares Mean Square
 Adjusted R Square  .91762 Regression    2     848.74140     424.37070
 Standard Error    1.81308 Residual     21     69.03272        3.28727

                           F = 129.09509   Signif F = .0000

VARIABLES IN THE EQUATION
Dependent Variable - Trip Rate Per Dwelling Unit

    Variable            B          SE B            BETA   T    SIG T

    Household size      3.86       .68371        .92105   5.643.0000
    Vehicle ownership   0.13       .47232        .04350   .267 .7924

                                     B-7





                                  TABLE B-4
                  TRIP RATES AS A FUNCTION OF MARKET VALUES
                          OF SINGLE FAMILY DETACHED
                            RESIDENTIAL DWELLINGS

                                      Medium Value(1)    High Value
                  Low Value(1)     (Mkt. Value between, (Mkt. Value >
             (Mkt. Value < $25,000) $25,000 & $50,000)     $50,000)
                   Trip    No. of     Trip   No. of     Trip   No. of
                   Rate   Dwellings   Rate  Dwellings   Rate  Dwellings

Delaware DOT       10.9     1700      11.6     770      13.8     304

Wisconsin DOT       8.5     1148      11.3    1198      16.0     256

Ohio Section ITE   10.1      506      10.2     715      14.3     12

Weighted Average   9.96     3354      11.09   2683      14.72   6,112

Computed Mean Trip Rate
                      9.96                 11.09            14.72

Standard Deviation    2.15                  2.31            3.05

No. of Studies       29                    39               8
___________________________

 (1)  In 1976 dollars

                                   B-8




    The ITE data base does not include "value of dwelling unit". 
Therefore, a direct correlation between the data presented in Table B-4
and the ITE data base cannot be made.  However, the trip rates can be
used for correlating the two sources.  The ITE data base correlates well
with the low market value database.  This would result in adjustment
factors of 1.10 and 1.50 for medium value and high value dwelling units
to be applied to the Table 3 trip rates of 10.03 trips per dwelling
unit.  It should be noted that the market values of dwelling units vary
for locations within the region as well as by geographic areas of
the country.  Therefore, this adjustment factor should be applied based
on low, medium and high values for the particular region rather than the
dollar value.

Home interview trip rate survey data from Detroit, Baltimore and
California were categorized by variables such as household size, vehicle
ownership, location, and income (12, 31, 79).  In the case of Detroit
and Baltimore, no comparable data from the augmented ITE data file could
be found to correlate the home interview surveys with the driveway
counts.  Trip rates based on driveway or ground counts data are more
applicable to site specific studies including determination of
roadway/intersection improvement needs.  For regional or areawide
studies, trip rates based on home interview (origin-destination) surveys
are more applicable.  The California DOT survey included summaries of
vehicle trip rates by household size as well as vehicle ownership for
single family and multi-family dwelling units.  T-tests were conducted
to determine the significance of difference of mean trip rates as a
function of household size.  The mean trip rates by household size were
found to be significantly different for single family dwelling units but
not for multifamily dwelling units.

                                   B-9








                               APPENDIX C
                  RECOMMENDATIONS FOR FURTHER RESEARCH

The ITE Permanent Trip Generation Committee (6A-32) has collected
extensive trip data since 1972.  In those cases where the sources of
data are known? it is recommended that the Committee request the sources
to provide data on trip location of the sites within the SMSA.  In
addition new data collection efforts are recommended, primarily in urban
areas, to develop trip rates by location for the appropriate land uses
in Table 3. Another area needing additional ground counts relates to the
residential uses in Baltimore and Detroit.  As discussed in Appendix B,
home interview data from these two sources are available, however,
adequate ground count data are not available for correlation of the two
sources.

The potential impact of new multi-use developments and planned unit
developments on the adjacent roadway network was previously discussed on
the basis of only two studies (70, 92).  More research is needed in this
area to validate/refine the study results.  Information on capture rate
of pass-by traffic is also very weak.  More research is needed to
identify the percentage of trips captured by a site from passing traffic
as well as the traffic diverted from another route to the new
development.  The research on multi-use centers and capture rates from
pass-by traffic would require origin-destination survey questionnaires
of patrons visiting the potential site uses (shopping centers,
restaurants banks, service stations, convenience markets and multi-use
centers).

Certain land uses such as shopping centers, restaurants and banks
exhibit significant daily and seasonal variations in trip rates.  For
many of these uses Friday trips are greater than the average weekday
trips.  Shopping centers exhibit seasonal peaks with January/February
the lower seasonal months and November/December the peak seasonal
months.  In some cases, Fridays or seasonal trip rates should be used as
the design or analysis period rather than the average weekday.  More
research is needed to develop this information.

U.S. Government Printing Office: 1985-461-816/20506

                                   C-1






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