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Impacts of Highway Facility Improvements On Travel and Regional Development - Wisconsin TransLinks 21
Click HERE for graphic. MISSION STATEMENT TRANSLINKS 21-Wisconsin's 21st century transporatation plan-will outline a comprehensive transportation system that moves people and goods efficiently,strengthens our economy, protects our environment, and supports our quality of life. Working with DOT, the public will identify Wisconsin's transportation needs-and help to make tomorrow's transportation choices. Tommy G. Thompson, Governor Charles H. Thompson Secretary Impacts of Highway Facility Improvements On Travel and Regional Development January 1994 ACKNOWLEDGEMENTS This report was prepared by the Wisconsin Department of Transportation, Division of Planning and Budget. The report was written by Barbara Kipp of the Bureau of Strategic Planning, Environmental Strategies Section. Significant input was provided by the following people: Lynne B. Judd, Chief of the Environmental Strategies Section; Ken Leonard, Director of the Bureau of Strategic Planning; Sari Radin and Sarah Dunning of the Environmental Strategies Section; Joanne Lazarz of the Urban System Planning Section; Sandra Beaupre, Chief of the Urban Strategies Section; Lisa Binkley and Sarah Jo Peterson of the Urban Strategies Section, Dan Yeh, Ron Atkinson and Jane Coffola of the Statewide System Planning Section; Marlin Beekman of the Division of Highways, District 6; Tom Batchelor, Deputy Director of the Division of Highways, District 1; John Hartz, Unit Leader of the Multi-Modal Planning Unit, Statewide System Planning Section; Robert McDonald of the Dane County Regional Plan Commission; Ken Yunker of the Southeast Wisconsin Regional Plan Commission; Ken Thein of the East Central Wisconsin Regional Plan Commission TABLE OF CONTENTS Introduction Chapter 1: Understanding Travel: the Basics . . . . . . . . . . . . . . .3 Travel Growth Trends. . . . . . . . . . . . . . . . . . . . . . . . . . .3 Important Underlying Conditions . . . . . . . . . . . . . . . . . . . . .4 Travel Growth in the Future . . . . . . . . . . . . . . . . . . . . . . .7 Impacts of Growth in Travel and Trip-Making . . . . . . . . . . . . . . .7 Chapter 2: The Role of Service Improvements in Travel Growth. . . . . . .9 Overview of Service Improvement Impacts . . . . . . . . . . . . . . . . .9 Short Term System Impacts . . . . . . . . . . . . . . . . . . . . . . . 10 Long Term Development Impacts . . . . . . . . . . . . . . . . . . . . . 12 What Conclusions Can Be Drawn About the Impact of Service Improvements? . . . . . . . . . . . . . . . . . . . . 14 Chapter 3: The Role of Travel Forecasting . . . . . . . . . . . . . . . 15 The Policy Environment. . . . . . . . . . . . . . . . . . . . . . . . . 15 Forecasting Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 What Conclusions Can Be Drawn About Travel Forecasting? . . . . . . . . 20 Chapter 4: Policy Options . . . . . . . . . . . . . . . . . . . . . . . 21 Introduction What are the impacts of highway capacity expansion on travel? How do transportation planning agencies evaluate and respond to those impacts? In recent years, it has been increasingly common for transportation professionals to be asked these questions as they consider the merits of making highway facility improvements, particularly in or near metropolitan areas. For many areas in the US, the question became urgent with the passage of the 1990 Clean Air Act Amendments (CAAA). The CAAA require that areas currently not meeting air quality standards for ground-level ozone and carbon monoxide give explicit consideration to the impact of the transportation system on air quality. In addition, the passage of the Intermodal Surface Transportation Efficiency Act in 1991 has placed increased emphasis on understanding how the transportation system interfaces with the natural and built environment. Beyond these very specific pieces of legislation, there is a more generalized concern on the part of environmental interest groups and public interest groups that the transportation planning process is not sufficiently sensitive to the environmental impacts of transportation system improvements on the environment and on many other aspects of urban life. WisDOT's interest in this issue relates to the concern that improved transportation facilities may quickly become inadequate if the level of travel which occurs on them is much greater than projected during the planning and design stages. The issues of the system's impact on land use, urban form, and the environment are explored in depth in several other TRANSLINKS issue papers. The degree to which the transportation system, the highway system in particular, contributes to creating travel demand is explored here. Growth in levels of traffic have been significant in the last twenty to thirty years. It is helpful to break down the factors of that growth to understand where and how it is occurring. This analysis is presented in Chapter One, which includes general background information about how much travel growth has been experienced in recent years and some of 1 the reasons behind the increased levels of travel growth. In Chapter Two, the research supporting the effort to understand the relationship between highway facility improvement and travel growth is discussed more fully. Changes in travel patterns can occur for a variety of reasons after an improvement is made to a highway facility or when transit services are reduced or improved. In the case of highway expansion, there is sometimes a concern that the improvement will lead to new travel which would not have occurred if the improvement were not made. This new travel, referred to as "induced" travel, is often the focus of environmental interest groups when the impact of a major highway improvement is discussed. Any effort to analyze when and how highway improvements will result in increased travel is a complex task, but one that planners are increasingly being called upon to assess. Chapter Three discusses the methods currently used to forecast travel and discusses current research underway aimed at improving these methods. A well-developed transportation system has long been acknowledged to be a key element in a healthy economy. It is equally clear that historically, transportation facilities have been significant determinants in the location and form of human settlements. As the nature of modem economies changes, the manner in which transportation facilities impact and shape communities must be re-examined. This paper will examine some of the issues which are key to understanding this relationship, to assist WisDOT in determining when and how to consider explicitly the impact transportation facilities will have on overall levels of travel. In Chapter Four, several policy options are presented which may have the potential to improve the way this issue is addressed in the Department's planning activities. 2 Chapter One Understanding Travel: The Basics Travel Growth Trends In 1990, the Federal Highway Administration (FHWA) conducted a new comprehensive survey, known as the Nationwide Personal Transportation Survey (NPTS) to assess the use of the various transportation modes and to provide information about characteristics of those traveling and the trips they made. The results were compared to surveys conducted previously, most recently in 1983 (Pisarski, 1992). The results showed that between 1983 and 1990, personal miles traveled (PMT) increased 19% nationwide, a rate of growth that is considered significant. Growth in vehicle trip rates (25 %) and vehicle miles of travel (VMT) (40 %) exceeded the growth in person trips and miles of travel. The growth in VMT is most often the focus of concern (rather than PMT) because of the impacts of additional vehicles on the transportation system and environmental impacts, on air quality in particular. A look at longer term data from Wisconsin shows similar trends in travel growth. Between 1960 and 1990, travel on Wisconsin's roadways for both personal and commercial activities increased tremendously. The data indicate that personal VMT increased by 138% while commercial VMT rose by 401%. Examination of the NPTS travel data shows that an increase in vehicle trip length is the single largest factor of increase, while an increase in the number of person trips/capita is second largest. Another significant contributor is the decrease in vehicle occupancy (number of persons per vehicle). Pisarski notes that vehicle occupancy patterns are important because of what they mean regarding the efficiency of private vehicle use and their congestion impacts. Increases in population and a shift to the auto from other modes also contributed to the overall increase in VMT. Trends in vehicle occupancy in Wisconsin mirror the national decrease. In 1980, less than 62% of all Wisconsin commuters drove to work alone; by 1990, nearly 75 % of trips to 3 work were made in single-occupancy vehicles (SOVs). As driving alone to work became more common, use of other modes -- carpooling, public transportation, walking, and bicycling all declined. Between 1980 and 1990 carpooling, public transportation, and walking each decreased by over 25 percent as the mode of choice for travel to work in Wisconsin. Important Underlying Conditions Underlying the increase in travel and these changes in travel patterns are important shifts in conditions which shape the travel environment and level of travel demand. These trends are independent of the addition of highway capacity. For example, in Southeastern Wisconsin, lane mileage on the highway system increased only 5 % between 1985 and 1992. An exploration of these underlying conditions is necessary to assess the likelihood that these travel trends will continue, and to separate the effects of these trends from possible induced travel effects due to new highway capacity. Economic Trends Aggregate levels of highway travel and economic activity are highly correlated. Between 1977 and 1983, there was a nationwide decline in overall trip-making rates which may have been reflective of the recession in the early eighties. The increase between 1983 and 1990 may be attributed partially to an increase in economic well-being. Higher levels of employment result in more commuters on the road ana higher personal incomes generally lead to higher levels of non-work-related trips. In Wisconsin increases in VMT correlate with higher income levels. Another significant economic variable is the cost of auto operation. Although the real cost (adjusted for inflation) of purchasing an automobiles has risen, the inflation-adjusted cost of gasoline has declined. When this declining cost is coupled with improved per-vehicle fuel economy, the decline in operating costs has been even more striking. Once the initial investment has been made in a vehicle, the declining day-to-day costs of auto operation have acted as a disincentive for vehicle owners to conserve on driving. Demographic/Social Trends Although overall increases in population are correlated with increases in VMT, VMT has 4 historically increased at a substantially faster rate than population. Of more significance than total numbers is the age makeup of the population. The heaviest driving years are between the ages of 35 and 54, while teenagers and seniors tend to drive significantly fewer miles than the average. Of particular interest are the effects of the large bulge in the population caused by the post World War 11 "baby boom". Because of their sheer numbers, the entrance of baby boomers into their peak driving years has had an impact on highway travel demand over the past twenty years. However, analysis of the NPTS data shows that the age shift of the baby boom generation between 1983-90 has begun to result in a slight decrease in trip-making, as that sector of the population has begun to move into the higher age groups with typically lower trip rates. This suggests that, long term, the growth rate in VMT is likely to moderate - at least to the extent that it is driven by the demographic profile of the population. Other major factors in determining overall trip rates are the number and size of households. Nationwide, the population of 1990 formed 4 million more households than that same population in 1983, thus resulting in more trips per person. Women's trip-making rate increased during the period, a change which seemed to be correlated with an increase in the proportion of women with driver's licenses, and the increased share of women employed outside the home. National data shows that work trips by women with driver's licenses are 50% longer than work trips by women without licenses. Thus, it appears that overall longer trips lengths are supported by access to the personal vehicle as a mode of travel. It should be noted that demographic changes that affect VMT may fluctuate from year to year, while longer term trends have a greater degree of stability and predictability. Suburbanization Throughout the country, one of the most significant factors in travel growth in the past has been the shift of population from central cities to suburban and exurban areas throughout the country. Older central cities were generally designed at high densities in a grid pattern that could be served efficiently by mass transit. In addition, urban areas often contain a variety of mixed uses, so residents have access on foot to a variety of employment and retail sites. In contrast, newly developed suburban sites are usually of lower density and often separate residences from other uses. 5 The NPTS data shows that, nationwide, transit's share declined more rapidly in suburban areas (where population growth is centered) than in central cities, probably as a result of several factors, including the longer transit wait times common in lower-density areas, and the availability of free parking at suburban work sites. The share of walk trips also declined, a trend which is likely to continue as jobs move to suburban locations (where distances may be too far for walking). In general work trip lengths increase with metropolitan size, in particular for central city residents who take jobs in the suburbs, or for central city workers who move their residences to the suburbs. Urban and metropolitan areas in Wisconsin have experienced suburbanization trends similar to the rest of the nation. For example, the seven-county southeastern Wisconsin region has seen significant density changes throughout this century. In 1920, the developed areas of the region housed an average of about 18 people per acre. As the region developed the density steadily declined -- in 1963 there were nine people per developed acre; in 1970 there were about eight people per developed acre; and by 1985 there were fewer than six people per developed acre in the region. This decrease in density and increase in distance between homes, work, and recreation brought with it a decline in the ability to travel by modes other than the automobile. The availability of convenient highway facilities is often cited as the chief contributor to the shift of jobs and households away from dense metropolitan areas, but the reality is more complex. Many American households prefer to own a single-family dwelling with private open space. John Shaw reports research that generally supports the notion that this is the preferred residential setting, particularly among families with children (1993). Thus, the shift of residences and employment centers to suburban areas may be a reflection, more than anything else, of the development community responding to the desires of home buyers. Since suburbanization stimulates travel, demand for new highway capacity frequently follows those trends, to sustain mobility. This is not to suggest that desirable communities which can support travel modes other than the single-occupancy vehicle cannot be developed. There is evidence that communities with many of the characteristics of suburban settings can be supportive of non-SOV modes. This issue is discussed in the TRANSLINKS report, Transportation and Land Use. Shaw cites the need for additional research which evaluates whether developments can be designed that are at 6 densities high enough to support transit, and also meet the preferences of consumers. Travel Growth in The Future The analyses of several researchers suggests that travel will not continue to increase in the 1990s as it did in the 1970s and 1980s because several of the forces behind the growth have moderated - that is, there is not another baby boom generation entering the peak driving years, the number of women obtaining drivers licenses and employment will stabilize, and vehicle occupancy rates (already very low) for work trips cannot continue to drop indefinitely. WisDOT estimates that VMT will increase by 34% between 1990 and 2020, reflecting an annual rate of increase of 1.9%, compared to 4.6% annual growth between 1960 and 1990. While overall travel growth rates may drop, the growth rates in individual corridors may continue to rise, thus straining their capacity. In 1989, a strategic planning effort known as Metro 2020 was undertaken in Southeastern Wisconsin with the goal of developing a set of comprehensive, long-range transportation policies for the region. One reason for the study was the concern about the potential for serious congestion problems as a result of the rate of VMT growth on the Interstate system in the metropolitan area. It was determined that as travel growth continues into the future, portions of the freeway system may experience up to 4-5 hours of congestion during the day. This pressure on particular corridors is likely to be experienced in other parts of the state, particularly in urbanized areas experiencing high rates of employment and population growth. The Impacts of Growth In Travel and Trip-making The auto has provided tremendous benefits in terms of convenience and freedom in our society and the high levels of auto travel in the U.S. are a reflection of the value that Americans place on access to goods, services and employment. Yet the development of any advanced transportation system is inherently disruptive to the physical environment. The less desirable effects of transportation (particularly auto-related) are well-documented and include: air pollution, water pollution, the oil dependent state of the U.S., noise, and loss of sensitive natural areas and agricultural lands. In addition to exacerbating the existing level of conditions related to these problems, the significant levels of growth in VMT quoted above can eventually 7 contribute to a deterioration in the quality of service on some roadways. That is, levels of congestion increase, making it more difficult to travel. From the standpoint of these many factors, significant travel growth presents problems. In some ways, the large increase in trip-making during the last decade does seem to represent undesirable trends. The decreased efficiency represented by the decrease in vehicle occupancy for work trips is of concern. There is some evidence that central city residents are forced to make long commute trips that are costly in terms of travel time and/or dollars because of the movement of jobs away from the central city to the suburbs. Often, there is limited availability of housing for low and moderate income families in these areas (Levine, p. 71). In other respects, the increase in travel may represent a bettering of conditions for certain groups. The increased mobility for women and low income groups, giving them the opportunity to accept jobs which are personally and financially more rewarding, is surely a positive outcome. To the degree that increased trip-making represents an improvement in the ability of an area's residents to partake in activities that they value, or live in locations they prefer, it would seem to be an indicator of an improvement in the quality of life along some dimensions for the state's residents. If it results in the loss of other mode options, or reflects a decline in the accessibility of employment for some sectors of the population, it may not represent increased well-being of the community, across the board. Chapter Two The Role of Service Improvements In Travel Growth Overview of Service Improvement Impacts Basic economic theory suggests that improvement to the transportation system that reduce the time and costs of travel will cause people to consume more travel (Brand, 1993, p. 5 1). This should not lead to an immediate conclusion that capacity expansion (or any other type of service improvement) should be viewed as negative - merely that transportation, as a commodity, is not exempt from rules that govern the way that all commodities are purchased and used in market economies. As noted previously, improved mobility can represent an improved quality of life on a variety of dimensions. However, the result may also be an overall decrease in system efficiency, if travel growth is high and travelers shift away from travel modes or patterns that maximized system efficiency. Brand notes why this shift occurs in certain congested corridors: The automobile/highway system is a classic example of a system characterized by individual choice behavior that puts private interests over the public interest. Every time a person drives a car onto a congested roadway, far more aggregate delay is forced on others - on the system - than on the driver. In economic terms, the marginal private cost of highway travel is mu@h less than the marginal social cost of travel on the already congested highway system. (op.cit, p. 108) It is this possibility for a decrease in system efficiency despite continued investment in transportation facilities that calls for a careful consideration of the impacts of transportation improvements prior to system expansion. Recent research postulates nine specific, potential effects of capacity addition: 1. Route changes 2. Mode changes 3. Trip timing changes 4. Destination changes 5. Trip frequency/trip chaining changes 9 6. Auto ownership changes 7. Residential location changes 8. Employment location changes 9. Regional growth changes in either population or employment (Stopher, 1992; Harvey and Deakin, 1991). Peter Stopher notes that the first five of these are likely to be short to medium term changes, i.e., occurring within the first two years after a capacity addition opens. The latter four are likely to be medium to long term with effects showing up at least one to two years after the addition is made, and as long as ten years later. He believes the short-term changes to be relatively easy to measure and to attribute to a capacity change, while the long term changes are more difficult to assess because other events and conditions over the course of time will have significant impacts. To a large extent, the "induced travel" effects are of most concern in urbanized areas or their fringes. Facility expansions on rural corridors may result in improving a region's access to other regions in the state or nation. For example, a significant highway expansion project may make an entire region more attractive to businesses which are heavily reliant on having efficient highway connections to national markets. This type of effect is generally considered desirable and not the subject of the discussion to follow. Of pertinence here is the issue of when impacts occur that "use up" the capacity needed to serve long distance travel. In the pages ahead, these potential effects will be discussed in more detail. Short Term System Impacts Travelers choose a travel route based upon a variety of factors: travel time, perceived safety, scenic amenities, directness, and road surface quality being the most obvious. Speed and the dumber of encumbrances (e.g., stop signals) are often the primary criteria drivers use (Downs, p.27). When a travel route (either roadway or transit route) begins to deteriorate along any of these dimensions, the driver may alter usual travel patterns to avoid the deteriorating conditions and seek a route that offers superior service. Conversely, when a route is improved, travelers may move to the improved route because it is superior to that formerly used. In either case, there is no net change in the amount of travel. 10 Anthony Downs presents the "Principle of Triple Convergence", as an explanation for why road expansions made to increase capacity and relieve congestion problems can sometimes provide only short term relief. As the road's carrying capacity increases, three changes may occur: 1. Drivers who formerly used alternative routes during peak hours switch to the improved facility (route convergence). 2. Drivers who formerly avoided peak times start traveling during these times (time convergence). 3. Commuters who used to take public transportation switch to driving (mode convergence). As more drivers converge on the improved facility, traffic volumes will rise and congested conditions may reappear. Downs points out that, despite the reappearance of congestion, social benefits have been realized: parallel routes will be relieved of some traffic, travel before and after the peak may be faster, and more people will be able to travel at peak hours which are presumably more convenient (p.27-28). The impact on public transit could be negative if transit users decide to switch to driving because of the improved conditions. The reality is, however, that many highway capacity expansions occur in areas where a transit route does not exist or does not compete well against the auto, even with congested roadway conditions. And as De Courla-Souza points out, "carpools-and buses operating on congested roadways have no advantage over single occupancy vehicles (1992, p.57)." There is some evidence that congestion on major arterials causes an increase in VMT in that travelers may choose more circuitous routes to avoid the congestion. Thus, congestion relief measures may draw these travelers to the improved facility, and decrease VMT related to those trips (De Courla-Souza, 1992, p. 157). These convergence effects fall into the category of diverted travel. Labelling these impacts as short term does not imply that they are either short-lived or inconsequential. A careful evaluation of the purpose of a capacity expansion project relative to these potential effects may yield a determination that another solution may be appropriate. On the other hand, such an analysis may conclude that either the effects are likely to be minimal, or that they may be significant but nonetheless the project will provide overall social benefits. 11 There is considerable evidence that the scale of diverted travel may be affected through the use of peak pricing mechanisms, such as tolls, which can act to deter travelers from shifting their travel into the peak travel times or onto the toll route (Decourla- Souza, p. 161). The term induced travel is quite distinct from diverted travel and can be used to refer to trips that were not taken prior to facility or service improvement. The improved service may result in increased travel because the improvement makes a particular trip more attractive. Presumably, these are trips that would not have been made at all (they involved activities that were optional for the traveler) or involved activities that would have been carried out in connection with another trip. This effect is generally believed to be small, relative to diverted travel effects, and development-induced impacts, discussed below. Long-Term Development Travel Impacts Induced travel can also result from new development that occurs as a response to a major facility improvement which brings about increased accessibility to an area. The assumption is that the service improvement is a factor (one of many) that encourages new development to, occur. This, in turn, may cause longer trips to occur, and may result in trips which were formerly taken by another mode (transit, walking, biking) to be taken by automobile. Ryuicha Kitamura suggests that the addition of transportation capacity may have some significant long-range impacts on household automobile ownership, residence, and job location choices. Improved access to/from fringe areas provided by new or expanded service may promote the geographic expansion of an urban area, and eventually result in new levels and patterns of travel in an urban area (1991). He believes this development-inducing impact to be the most important impact, while the changes discussed earlier to be secondary because they may be small compared to the primary growth impact. He points out the difficulty in attempting to disaggregate the effects of transportation supply, land use, accessibility, and travel demand, which together form a dynamic and interrelated system. Guiliano (1986) echoes the difficulties in understanding transportation supply and land use interactions. She notes that many highway investments are marginal in terms of accessibility impacts - i.e., they add some increased accessibility to areas that already have a high degree of accessibility. In these cases, a highway improvement cannot be expected to have much impact 12 on land use. In areas with limited accessibility, the same project may have a much greater impact. She suggests that in these areas the availability of developable land is a key consideration. Not only must there be open land parcels, but there must be an absence of zoning regulations that would restrict development. In addition, the overall state of the regional economy is important. An improved facility is not likely to result in a significant level of new growth in areas where the economy is in decline. The impact of the new development on the improved facility may vary, depending upon what types of land uses appear. The new development could be homogeneous in nature, a "bedroom community" of single-family homes, generating many new trips to employment and ,shopping locations outside of the community. If zoning regulations and incentives are in place to promote mixed use development - employment, retail and residential uses - a new development center may result. In. this case, some proportion of trips generated by the new residents will be made within the new center, although it is likely that many commute trips will continue to be made to adjacent communities. An important concern is the tendency of local policy-makers to focus on the immediate benefits to the community of a proposed development while discounting or ignoring the demands it may place on state highway facilities. This problem can be addressed to some extent by improving coordination between local/regional land use planning and state-level transportation planning. The impact of land use on transportation facilities is covered in the TRANSLINKS report, Transportation and Land Use: Here, it is sufficient to note that the impact of improved access on levels of travel is very much related to the economic and land use regulatory environment in the area. In Wisconsin, new development is generally occurring along existing highway routes in response to changing market forces, rather than as a result of new capacity. The development-induced travel is, in turn, generating demand for new highway capacity. Finally, access management on a new or newly expanded regional facility can affect the level and type of development impacts that occur in the vicinity of the improved facility. If the number of entrances onto a roadway is not controlled, new development may spring up along the roadway generating many more trips than were anticipated when the improvement was designed. In addition, the presence of many intersections on an improved facility will compromise its safety. If access is well- managed along the facility, this type of development 13 is less likely to occur. A discussion of the importance of access management in protecting the capacity and efficiency of a highway corridor is found in the TRANSLINKS report Corridor Preservation and Access Management Guidance. If land use controls are in place along the corridor, new development may concentrate in more desirable locations, if other conditions are conducive for growth in the area. If these communities have land use regulations in place that promote mixed uses, and support modes of travel other than the auto, the result may be a new development center that is more efficient, from a transportation standpoint. In this ideal scenario, the function of the highway facility for intercity travel has been preserved, auto- oriented patterns of sprawl development have been avoided, and accommodation has been made for new development. What Conclusions Can Be Drawn About the Impact of Service Improvements? Under many circumstances, significantly enhanced service (whether due to transit service expansion or highway improvements) are likely to impact travelers' choices regarding travel route, time of travel, mode of travel, destination, and trip frequency/trip chaining The degree to which any of these effects occurs is dependent upon facility conditions existing prior to the improvement, and the availability of alternative routes and modes. In addition, the effects in urban areas may be different from the effects in rural areas. Facility/service changes that greatly improve access to an area may have development impacts in the newly-accessed region. The extent, type and location of the development impacts will depend on other conditions - in particular, the regional economic climate, the land use regulatory environment, and the level of access management exercised along the facility. If an appropriate combination of access management policies and land use controls are in place, highway expansion can meet the demand for transportation facilities without compromising efficiency or safety, and can support desirable regional development patterns. If such controls are not in place, highway facility improvements may contribute to auto-oriented patterns of development. The result may be unanticipated levels of travel on the improved facility, and a decline in the quality of service on the facility from what was expected. 14 Chapter Three The Role of Travel Forecasting The Policy Environment The methods that are used to forecast future levels of travel determine whether improved facilities or services are provided, and when. Thus, these methods play a pivotal role in the planning process. It is important that they predict, with some accuracy, not only what the level of demand is likely to be before an improvement is made but also, to the degree possible, what impact the facility itself will have on demand - i.e., diverted travel effects, and development related effects. Two important pieces of legislation have been enacted in recent years that have placed increased importance on planning and forecasting processes. ISTEA In December of 1991 the federal government adopted the Intermodal Surface Transportation Efficiency Act (ISTEA). The purpose of the act, as described in its statement of policy, is "to develop a National Intermodal Transportation System that is economically efficient, environmentally sound, provides the foundation for the Nation to compete in the global economy and will move people and goods in an energy efficient manner." ISTEA established a requirement for a statewide planning process that considers the economic, environmental and social effects of transportation decisions. It also strengthened the metropolitan planning process by giving more emphasis to the impacts of transportation policy decisions on land use and the consistency between transportation plans and land use plans. CAAA In November 1990, President Bush signed the Clean Air Act Amendments (CAAA) into law. The CAAA set new requirements in place for areas of the country which currently do not meet air quality standards. In Wisconsin, there are 11 counties (designated as nonattainment areas") which violate the standards set for ground- level ozone, a component of smog. The law requires the state to revise its air quality plan and to submit those revisions to 15 the U.S. Environmental Protection Agency (EPA) for approval. The revisions will be prepared in installments over the course of several years, with the first revisions due in November of 1992. The Wisconsin Department of Natural Resources (DNR) is responsible for submitting the air quality plan revisions to EPA. Because motor vehicles are a significant source of air pollution, the CAAA contain several provisions aimed at controlling pollutants from motor vehicles. WISDOT is working closely with DNR on the transportation-related portions of the air quality plan. An important provision in the CAAA is the "Conformity" requirement, which requires that the level of motor vehicle emissions forecasted to result from implementation of the transportation plan in a metropolitan area must be consistent with the level of motor vehicle emissions forecasted to occur in t@e air quality plan. The state must develop a process for carrying out a Conformity review of the long-range transportation plan and the shorter-term Transportation Improvements Program (the TIP - a list of projects scheduled for implementation in the near term) in the seven-county nonattainment area in Southeast Wisconsin and the Sheboygan Urbanized area. In the short term, implementation of the plan and program must result in a net reduction in emissions from mobile sources. In the long term, implementation will help bring the area into attainment for ozone standards, and keep pollution below the caps set in the air quality plan. This process will not require each project in the transportation plan and program to be analyzed individually, rather it requires transportation plans and programs to be analyzed as a whole. This analysis is done using the region's travel model, and the MOBILE model, developed by EPA to estimate the emissions resulting from the levels of travel projected to occur. It is also necessary to develop a process for assessing the air quality impacts of individual projects which are in rural nonattainment areas - namely, rural Sheboygan, Manitowoc, Kewaunee and Door Counties. If the plans or projects do not pass the Conformity test, federally funded transportation projects in those counties cannot proceed. State and locally-funded projects will be able to proceed, but any emissions increases which result from those projects will have to be offset in other ways, in order for mobile source emissions to stay below the caps. States must track 16 actual levels of travel and compare them to the forecasted levels. If actual travel is higher than what was forecasted, compensating measures must be implemented. As a result of the Conformity and VMT tracking requirements in the CAAA, the accuracy of transportation planning and forecasting processes have taken on a new level of importance. Forecasting Tools There are several ways in which transportation planners attempt to look into the future, and varying purposes for doing so. Following is a brief summary of travel forecasting activities - their purposes, methodologies and an assessment of their adequacy. Statewide Forecasts WisDOT periodically prepares a statewide highway travel forecast extending 20+ years into the future. These forecasts are based upon an analysis of expected future demographic profiles of the population and assumptions regarding the number of miles traveled by various sectors of the population. The major factors considered are those discussed earlier in the travel growth trends section. The purposes of the forecast are to provide a very general picture of travel in the future and to assist in developing forecasts for specific highway projects. The statewide forecast is used as a control total for adjustment of the individual project forecasts. Corridor/Segment Forecasts WisDOT currently measures traffic volumes at approximately 20,000 locations on the State Trunk Highway (STH) System and on urban streets. Traffic counts from each location are usually taken every three years, and certain seasonal and axle-adjustment factors are applied. The result is an Average Annual Daily Traffic (AADT) volume for that location. For purposes of carrying out system and corridor-level planning, the roads on the State Trunk Highway System are divided into specific segments, with traffic counting devices placed at both ends of the segment. In order to develop a long-range forecast of travel on a particular segment, historical trends are analyzed using the AADT volumes from the three most recent counts (three counts, taken over five to six years). The trends resulting from the forecast of overall travel in the state are also considered in determining the shape of the forecast curve. An important determinant of the reliability of the forecast for a particular segment is the degree to which the past history of the segment is an indicator of future activity levels. It is also important that the 17 overall levels of travel are homogeneous throughout the segment. If this is not the case, the traffic count data may not accurately represent what is actually occurring over the entire segment, for example. In addition to the forecasts produced for the system level analysis, WisDOT conducts a more in-depth analysis before proceeding with an improvement in non-metropolitan areas. Here, a variety of factors may be considered, including specific employment variables, and projected land developments. WisDOT's long-range planning process will undergo a change in 1994, with the development of a new computer model to forecast intercity levels of travel for passenger and freight vehicles, and predict modal shares. The details of how this model will function are not yet available. Travel Forecasting In Urbanized Areas For many years, the state's urbanized areas have used a computerized, four-step travel demand model. Region-specific inputs reflecting population, employment, households, current and planned land uses, and the transportation system are entered into the program. Travel surveys are conducted to calibrate the model, to reflect regional travel patterns. A large percentage of the state's travel occurs within these urbanized areas, and the travel model is viewed as a critical tool in understanding the complexities of the urban travel environment. Without it, it would be extremely difficult for transportation planners to predict what the demands on the system will be in the future, and to make decisions about responding to that demand. The model being used today in Wisconsin's urban areas meets or exceeds the basic modeling requirements contained in ISTEA and the CAAA. However, both ISTEA and the CAAA have put increasing pressure on the transportation planning community to make forecasting assessments that are not necessarily within the capabilities of current modeling practices. One area under discussion is whether the modeling process should better reflect how hospitable the built environment is to modes of travel other than the automobile. This would require a model that could reflect variables such as building setbacks, the presence of sidewalks, bicycle lanes, etc. Also of great interest is developing the capability to model the effects that 18 improved accessibility have on land use development activities, and the corresponding impacts on levels of travel - discussed in the previous chapter. In addition to the potential changes discussed above, there are other less sweeping changes under consideration to improve model performance. Two major research efforts now underway bear mentioning. The Federal Highway Administration (FHWA) has undertaken a Travel Model Improvement Program. This is a multiyear effort that has three tracks - short, intermediate and long-term. In the short-term track, efforts are underway to disseminate information on the best of current practices. The intermediate track is focusing on improving how traffic is assigned to particular roadways in the model. The long term effort involves more fundamental changes to the model to improve accuracy, sensitivity, and responsiveness (Weiner, 1993). A second effort is a research project sponsored by 1000 Friends of Oregon, an organization which focuses on growth management issues. The study, known as LUTRAQ ("Making the Land Use, Transportation, Air Quality Connection") is a demonstration project to develop methodologies for creating and evaluating alternative land use patterns and design standards that will reduce dependence on automotive travel, improve mobility for all segments of society and minimize environmental impacts of the transportation system. One important element of the project is an evaluation of current and new transportation model methodologies. This evaluation has concluded that the tools in use today are not sufficient to meet the new demands being placed upon them. Fourteen commercially available models were evaluated, with three packages selected as potentially the most useful to meet these demands (Cambridge Systematics, 1991). There is one final issue which should be considered when evaluating the impact of land use changes on the transportation system is the time frame in which transportation modeling is conducted, usually 20 years. Because the scale of an existing metropolitan area is so large relative to new development, the travel impacts of new development may appear to be minuscule, and the benefits of developing a multi-modal travel environment and system insignificant. Over a longer time frame (30-40 years), however, those same impacts and benefits take on more significance. 19 What Conclusions Can Be Drawn About Travel Forecasting? Either directly or indirectly, both ISTEA and the CAAA have placed a new emphasis on travel forecasting processes. ISTEA requires that the transportation planning process consider the impacts of transportation policy on land use, and the CAAA require that areas which do not meet air quality standards track levels of travel and compensate when actual levels exceed forecasted levels. Nationally, new computer simulation forecasting methods are being explored to improve the ability of planners to understand the impact of facility and service improvements in metropolitan areas. In non-metropolitan areas, Wisconsin has developed a variety of techniques for forecasting levels of travel, determining the appropriateness of capacity expansion, and evaluating the impacts of expansion. On-going efforts to improve these practices should continue. 20 Chapter Four Policy Options The transportation planning environment is changing in response to new federal legislation and increasing concerns about the impacts of transportation facilities on the natural and built environment. Through the TRANSLINKS process, WisDOT hopes to gain an improved understanding of the critical forces that shape the transportation system. The methods used to assess the need for new facilities in the future and evaluate the impacts of new or expanded facilities are at the heart of the evolving transportation planning process. Transportation agencies (state and local) are being challenged to improve their traffic forecasting and evaluation capabilities. Several options (not mutually exclusive) for meeting this challenge are presented here. 1. Evaluate impacts of a proposed project on the project corridor and neighboring communities. This evaluation would be conducted in the system planning process and could contain the following elements: a. Evaluate potential for residential or employment increases based on a variety of factors: -available work force -community plan & existing zoning regulation -existence of water/sewer infrastructure -regional growth trends & economic climate -unique community amenities (e.g., waterfront) -tax climate -expected employment opportunities b. Conduct an alternatives' analysis which includes a range of potential development 21 scenarios, based upon the level of improved accessibility and the factors listed in a. c. Estimate levels of travel on the improved facility associated with the potential development scenarios and the resulting environmental impacts. d. Coordinate system plan decisions to link planned land uses in a corridor with transportation improvements that will serve it efficiently. This will help assure that travel impacts from a transportation investment as planned for are acceptable to the community. 2. Consider methods to incorporate diverted travel impact considerations into major project analyses. As part of alternatives' analyses, the Department could conduct stated preference and origin/destination (O/D) surveys on routes targeted for improvement, parallel corridors, and transit routes to determine likelihood that facility improvement will result in diverted travel. It may also be useful to conduct O/D travel surveys on recently improved corridors to determine if diverted travel has occurred as a result of improvement, separating this impact from other influences in the region. These efforts may assist in developing new evaluation techniques to incorporate into future alternatives analyses. 3. Develop a research program to evaluate potential improvements in modeling and forecasting techniques for urbanized areas. A program such as this could contain several elements: A state-initiated transportation modelers' network to serve as an information exchange forum for state, regional and local transportation planners Regular review of national research efforts Participation in national research and policy-making efforts Use of experimental model applications in select communities or corridors Adoption of model improvements supported by sound research and theory 22 4. Develop a plan to systematically improve the segmentation of links on rural intercity routes. As discussed in Chapter 3, proper segmentation is important for the development of accurate forecasts on corridors. The Department has the ability to easily update segmentation files and should develop a plan to do so. Prior to undertaking a capacity expansion project based upon forecasts of future congestion, the segmentation for the corridor under discussion should be closely examined. This would not apply on Corridors 2020 routes, where expansion needs have already been extensively analyzed. 5. Improve coordination between local land use activities and state transportation investment activities. Local land use controls appear to be a critical variable in assessing how an expansion of a highway facility will impact a region's travel patterns. Improving coordination in this area may result in more effective use of transportation investment dollars and have a positive impact on regional development patterns. Specific policy alternatives for achieving improved coordination are discussed in the TRANSLINKS issue paper Transportation and Land Use. 23 References Brand, Daniel. Use of Travel Forecasting Models to Evaluate the Travel and Environmental Effects of Added Transportation Capacity". In Proceedings from Conference "Effects of Added Transportation Capacity, December 1991; Texas Transportation Institute, College Station, Texas. Cambridge Systematics. "Modeling Practices", Volume I of Making- the Land Use-Transportation Air Quality Connection, a study sponsored by 1000 Friends of Oregon. October 1991. DeCorla-Souza, Patrick. "The Transportation-Air Quality Connection: Perceptions and Reality". ITE 1992 Compendium of Technical Papers, Downs, Anthony. Stuck in Traffic. The Brookings Institution, Washington, D.C., 1992. Giuliano, Genevieve. "Land Use Impacts of Transportation Investments: Highway and Transit" in The Geography of Urban Transportation, ed. Susan Hanson. Guilford Press, 1986: NY, NY. Harvey, Greg and Deakin, Elizabeth. "Toward Improved Regional Transportation Modeling Practice". Paper presented to the National Association of Regional Governments Workshop on Transportation Planning for Air Quality. Kitamura, Ryuichi. "Me Effects of Added Transportation Capacity on Travel: A Review of Theoretical and Empirical Results".. In Proceedings from Conference "Effects of Added Transportation Capacity", December 1991; Texas Transportation Institute, College Station, Texas. Levine, Jonathan C. "Decentralization of Jobs and Emerging Suburban Commuting" Transportation Research Record, No. 164, p. 71-80. Transportation Research Board, 1992. Pisarski, Alan E. Travel Behavior Issues in the 90's. US Department of Transportation, Federal Highway Administration. 1992 Pisarski, Alan E. "Transportation Investment and Metropolitan Economic Development: A Reconnaissance of Research Availability and Requirements". In Proceedings from Conference 'Effects of Added Transportation Capacity", December 199 1; Texas Transportation Institute, College Station, Texas. Shaw, John. "Transportation, Land Use and Residential Choice". Preprint of paper presented at Transportation Research Board 72 Annual Meeting, January 10-14, 1993, Washington D.C. Stopher, Peter. "Travel and Locational Impacts of Added Transportation Capacity: Experimental Designs. In Proceedings from Conference "Effects of Added Transportation Capacity", December 1991; Texas Transportation Institute, College Station, Texas. Weiner, Ed., "Upgrading U.S. Travel Demand Forecasting Capabilities" in The Urban Transportation Mo July 9, 1993. WISCONSIN TRANSLINKS21 FOR MORE INFORMATION ON THIS TOPIC, CONTACT: LYNNE B. JUDD CHIEF, ENVIRONMENTAL STRATEGIES SECTION WISCONSIN DEPARTMENT OF TRANSPORTATION P.O. BOX 7913 MADISON, WI 53707-7913 608/266-7079 FOR ADDITIONAL COPIES, CALL: OFFICE OF PUBLIC AFFAIRS, 608/266-3581
