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Page 1
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2008. Effects of TOD on Housing, Parking, and Travel. Washington, DC: The National Academies Press. doi: 10.17226/14179.
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Page 2
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2008. Effects of TOD on Housing, Parking, and Travel. Washington, DC: The National Academies Press. doi: 10.17226/14179.
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Page 2
Page 3
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2008. Effects of TOD on Housing, Parking, and Travel. Washington, DC: The National Academies Press. doi: 10.17226/14179.
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Page 3
Page 4
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2008. Effects of TOD on Housing, Parking, and Travel. Washington, DC: The National Academies Press. doi: 10.17226/14179.
×
Page 4
Page 5
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2008. Effects of TOD on Housing, Parking, and Travel. Washington, DC: The National Academies Press. doi: 10.17226/14179.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

S U M M A R Y This research helps confirm what had been intuitively obvious: in the four metropolitan areas studied, transit-oriented development (TOD) housing produced considerably less traffic than what is generated by conventional development. Yet the way parking is designed for most TODs is based on the assumption that there is little difference between TOD and conventional development with respect to the traffic they generate and the parking spaces they are built with. One likely result of this fallacious assumption is that fewer TOD projects get built. TOD developments that do get built are less affordable and less sustainable than they might be, because they are subject to incorrect assumptions about the traffic impact they generate. Many of the hoped for benefits (i.e., less time stuck in traffic and lower housing costs), from the nearly $75 billion in public dollars invested in rail transit over the past 11 years, are not being realized. The policy value of TOD projects (e.g., less automobile travel) is well understood. Those potential benefits are muted since most U.S. TODs are parked oblivious to the fact that a rail stop is nearby. This study looks at the most recent literature on the subject and the actual transportation performance of 17 TOD projects. The report is divided into two sections: • Section 1 - Literature Review • Section 2 - Research Findings Literature Review A lot more is known now about the travel performance of TODs. Whereas the first genera- tions of TOD focused primarily on advocacy and assisting early adopters, there now is increased measurement and understanding of TOD travel outcomes. Some key findings in this literature review include: • Between 1970 and 2000, transit ridership for work trips increased in TOD zones, whereas rid- ership declined markedly in the metro areas surrounding TODs. • TOD households are twice as likely to not own a car and own roughly half as many cars as comparable households not living in TODs. • Among the factors that attract households to TOD, households consistently place high value on neighborhood design, home prices and perceived value, and transit proximity. • Access to high quality transit is becoming increasingly important to firms trying to attract creative class workers (professionals who use knowledge to create new forms and problem solve, such as architects, engineers, professors, artists, computer programmers, etc.) in the knowledge economy (the current phase of post-industrial United States, where economic Effects of TOD on Housing, Parking, and Travel 1

2development in cities is primarily through jobs and industries that are based on intellectual property). The literature review focused on nine questions related to TOD travel characteristics, transit system and land-use influences, TOD ridership strategies and TOD resident/tenant characteris- tics. The most current knowledge on TOD was analyzed. The following is a summary of the key conclusions for each question. TOD Travel Characteristics 1. What are the travel characteristics (e.g., frequency of travel by different modes) of people who live or work in a TOD? 2. What was the travel pattern of the TOD resident prior to moving to the TOD? TOD commuters typically use transit two to five times more than other commuters in the region. TOD transit mode share can vary from 5% to near 50%. The findings are similar for non- work trips: transit share is two to five times higher, although mode shares are typically lower than commute trips (2% to 20%). The primary reason for the range is that transit use is heavily influenced by relative travel times with automobile and extensiveness of transit service, which can vary markedly across regions. As the transit network links to more job centers, educational opportunities, and cultural facilities, transit use increases. From this perspective, TOD type (e.g., suburban neighborhood versus suburban center) is less important than specific location within the region and the quality of connecting transit service. Although one could reasonably infer the approximate transit mode share of a hypothetical new TOD by comparing it to similar TODs in the same, existing system, there is no rule of thumb or single mode share number that can be easily applied to a hypothetical new TOD along a new rail or bus system. This is due to widely varying local travel conditions and employment distributions. A primary reason for higher TOD transit use is self-selection. Current transit users and those precluded to use transit seek out TOD. The travel pattern of TOD residents prior to moving to the TOD depended on their previous access to transit. When work location was unchanged, often a significant percent (e.g., 50%) were transit users. Among commuters with no previous transit access, transit use increased (up to 50%). Transit System and Land Use Influences 1. What levels of transit connectivity to desired origins and destinations are required to promote transit ridership at TODs? 2. What TOD land-use and design features (e.g., mixed land use, traffic calming, bus bulbs, short blocks, street furniture) have had an effect on travel patterns, transit ridership, or the decision to locate in a TOD? Research shows that system extensiveness is positively correlated with transit ridership. Exten- sive transit networks also are most often found in cities with worse traffic congestion (i.e., slow auto trip times) and higher parking costs, and these three factors work together to increase TOD transit ridership. The general consensus is that transit service headways of 10 minutes are ideal to support a transit lifestyle. There is no single, definitive threshold for connectivity, and measures such as track miles and number of transit stations are not the best predictors of ridership on their own. What matters is transit travel times relative to auto travel times. For example, an extensive but very slow transit system likely will attract few riders if highway congestion is not severe. Conversely, a single fast rail corridor adjacent to a highly congested auto corridor likely will attract high ridership.

The location of jobs accessible by transit influences transit ridership. Systems that generate the highest commute ridership have a high percentage of regional jobs accessible by fast transit. For work trips, proximity to rail stations is a stronger influence on transit use than land use mix or quality of walking environment. Thus, the most effective strategy to increase TOD ridership is to increase development densities in close proximity to transit. Employment densities at trip ends have more influence on ridership than population densities at trip origins. It is critical to locate jobs near transit in order to attract households to TODs. However, relative travel time (transit versus auto) is still more important than any land use factor (density, diversity of uses, design) in ridership. Mixed uses in TODs allow the transit service to be used for a variety of trip purposes through- out the day and week, but as a travel benefit, this is not a primary consideration for prospective TOD residents. Employment access is a primary consideration. Mixed uses (e.g., local restau- rants) and urban design treatments (e.g., pedestrian pathways) are important for their amenity and design value in attracting residents and visitors or customers. TOD residents highly value good neighborhood design in addition to transit access to work. Urban design and the local land- use mix may influence which TOD prospective residents choose to live in. Good design also may make a TOD a more desirable location to travel to. TOD Ridership Strategies 1. What motivates or impedes transit ridership in a TOD? 2. What strategies have been effective in increasing transit ridership at TODs? 3. What steps should transit agencies take in supporting TODs to maximize transit ridership? Factors that most influence transit ridership are station proximity, transit quality, and park- ing policies. Fast, frequent, and comfortable transit service will increase ridership, as will high parking charges and/or constrained parking supply. The availability of free or low-cost parking is a major deterrent to transit ridership. Successful ridership strategies include: TOD transit pass programs, parking reductions, and car-sharing programs. TOD transit programs will be similar to other transit programs. That said, because TOD residents and households are by definition the nearest to transit, TODs should be among the first locations that transit agencies implement specialized programs. TOD (e.g., mixed uses, high densities, reduced parking) is still illegal around station areas in many cities and transit districts, creating a barrier for development. Steps that transit agencies are taking to promote TOD include: reconsidering replacement parking requirements at park and rides, advocating for zoning changes with TOD entitlements, land assembly, joint develop- ment, and educational efforts (e.g., producing TOD guidebooks). TOD Resident/Tenant Characteristics 1. What are the demographic profiles of TOD residents and employers? 2. What motivates residents or employers to locate in TODs? Examples of motivators may include the quality of schools, access to jobs, housing affordability, presence of transit ser- vices, neighborhood services and amenities, and community perception. The majority of TOD residents along new transit systems are childless singles or couples. The age spectrum is wide: often younger working professionals or older empty-nesters. TOD residents may have low, medium, or high incomes; this is driven by the design and price of the specific TOD housing. TOD developers are researching the market and proactively building products for tar- geted market sectors. The demographic characteristics allow developers to more finely target their 3

4product to potential end users. More higher incomes are being served as the United States con- tinues to go through a robust construction phase of denser urban residential product. TOD households typically own fewer cars because they have smaller households and because they may forgo extra cars due to transit’s proximity. TOD households are almost twice as likely to not own any car and own almost half the number of cars of other households. The top three reasons households give for selecting a TOD are housing/neighborhood design, housing cost, and proximity to transit. TOD Housing Transportation Performance Actual transportation performance of 17 TOD built projects was assessed by using pneumatic tubes stretched across the driveways to count the passage of motorized vehicles. The housing projects of varying sizes are in four urbanized areas of the country: Philadelphia/N.E. New Jersey; Portland, Oregon; metropolitan Washington, D.C.; and the East Bay of the San Francisco Bay Area. To help understand the physical implications of the research, eight residential TOD site plan case studies were developed to test some of the physical implications of reducing residen- tial parking ratios at a range of potential densities on a theoretical eight acre TOD. One motivation for this research was to provide original and reliable data to help seed an update of the Institute of Transportation Engineers (ITE) trip generation and parking genera- tion rates, from which local traffic and parking impacts are typically derived, and impact fees are set. (A specific objective of the research has been to help prepare the way for ITE and ULI to update their guidance on parking for TODs to better reflect actual performance.) Some analysts are of the opinion there is a serious suburban bias in current ITE rates. Typically, empirical data used to set generation rates are drawn from suburban areas with free and plentiful parking and low-density single land uses. Since ITE’s auto trip reduction factors are based only on a few mixed-use projects in Florida (to reflect internal trip capture), there has been little or no obser- vation of actual TODs. The end result is that auto trip generation is likely to be overstated for TODs. This can mean that TOD developers end up paying higher impact fees, proffers, and exactions than they should since such charges are usually tied to ITE rates. Results of this research clearly show that TOD-housing results in fewer trips in the four urbanized areas that were studied. The research confirms the ITE trip generation and parking generation rates underestimate automobile trip reduction for TOD housing. The ITE manual presents weighted averages of trip generation. The weighted average vehicle trip rates for this study were computed for all 17 projects combined for weekday, AM peak, and PM peak. Over a typical weekday period, the 17 surveyed TOD-housing projects averaged 44% fewer vehicle trips than estimated by the ITE manual (3.754 trips versus 6.715). Weighted average differentials were even larger during peak periods: 49% lower rates during the AM peak and 48% lower rates dur- ing the PM peak. To the degree that impact fees are based on peak travel conditions, one can infer that traffic impacts studies might overstate the potential congestion-inducing effects of TOD-housing in large rail-served metropolitan areas, such as Washington, D.C., by up to 50%. One implication of the research is that parking ratios for residential TODs are likely to be over- stated by the same order of magnitude since they also are based on ITE data. Some of the cumulative impacts of over-parking TODs are illustrated in the site plan case studies. TOD site plan case studies help to demonstrate that under the right conditions lowering residential park- ing ratios by 50% for TODs in station areas with quality transit service can result in: • An increase between 20% to 33% in the potential density of a residential TOD, depending on the residential building type; • Savings from 5% to 36% on residential parking costs, after accounting for increases in the number of units to be parked from increased residential density; and

• Potentially greater developer profits and/or increased housing affordability from achieving higher densities, lower capital costs for parking, and reduced traffic impact fees. Rightsizing parking ratios and traffic generation to the actual performance of TOD would likely result in some important implications on the physical form and performance of TOD developments: • Local officials and neighborhoods may be more apt to support increases in residential densi- ties near transit if research shows TODs result in fewer trips than conventional development. • TOD developers would have easier development approvals and the benefits of TOD would not be compromised away. • TOD developers would likely pay lower traffic-related impact fees and exactions. Those savings could be passed on to consumers as lower housing costs. • With lower levels of traffic generated from TODs, it could be argued that it makes no sense to construct roadway improvements for TOD-related traffic that is not likely to materialize. • Rightsizing new road and intersection improvements to reflect actual transportation per- formance could result in more compact development patterns and a higher quality pedestrian environment since less land may be used for road improvements. • The potential for higher densities in TODs because of the decreased amount of land dedicated to parking and the reduced cost of parking. Smart growth requires smart calculations; impact fees, parking ratios, and road improvements need to account for the likely trip-reduction effects of TOD. Research study results indicate that residential TOD parking ratios can be tightened and fees lowered to reflect the actual trans- portation performance of TODs. Given that TODs have historically been over-parked, the incorporation of research results into revised parking ratios is an important step toward national recognition of the expected community benefits of TOD. 5

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TRB’s Transit Cooperative Research Program (TCRP) Report 128: Effects of TOD on Housing, Parking, and Travel explores the demographics of transit-oriented development (TOD) residents and employers, and their motives for locating in TODs. The report also examines the travel characteristics of residence before and after moving to a TOD and ways to increase transit ridership among these residents. In addition, the report reviews the potential effect of land-use and design features on travel patterns, transit ridership, and the decision to locate in a TOD.

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