Click for next page ( 5

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 4
4 product 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

OCR for page 4
5 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.