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54 land costs constituting 50% of the total market value of confirm whether TOD residents own cars at the same rate as housing. TOD site plan case studies suggest reducing park- conventional development, but use them less. ing ratios to reflect that the transportation performance of Some cumulative impacts of over-parking TODs are illus- TODs also can have the additional benefit of increasing the trated in the site plan case studies. The TOD site plan case number of housing units on the same piece of land by studies help to demonstrate that under the right conditions between 20% and 33%, which can translate into lower lowering residential parking ratios by 50% for TODs in station housing costs (Davis and Palumbo, 2006). areas with quality transit service can result in: The TOD housing affordability connection has received An increase in the density of a residential TOD by 20% to attention from some housing advocates because automobile 33% depending on the residential building type; ownership is one of a household's largest expenses, second Savings on residential parking costs from 5% to 36% after only to the cost of housing. [According to the Bureau of accounting for increases in the number of units to be parked Transportation Statistics, in 1998 the average household from increased residential density; and spent 33% of its income on housing and 19% on transporta- Potentially greater developer profits and/or increased hous- tion (Only 6% of transportation spending went toward travel ing affordability from higher densities, lower capital costs by air, taxi, and public transportation). Food related expen- for parking, and reduced traffic impact fees. ditures come in third, at 14%. Bureau of Transportation Sta- tistics. Pocket Guide to Transportation, U. S. Department of Rightsizing parking ratios and traffic generation to the ac- Transportation, BTS00-08, 2000.] tual performance of TOD is likely to result in some important The poorest families spend the greatest share of their income implications on the physical form and performance of TOD on transportation (Surface Transportation Policy Partner- developments: ship, 2001). Instead of paying a quarter or a third of their income for housing, low-income families sometimes pay half Local officials and neighborhoods may be more apt to sup- or even more for a place to live. Reducing transportation port increases in residential densities near transit if they are expenditures by living in TODs can free-up disposable in- shown proof that fewer trips result from TODs than in come to be used for other uses such as housing. conventional development. TOD developers likely would pay lower traffic related im- pact fees and exactions. Those savings can be passed on to Conclusion and Recommendations consumers as lower housing costs. This research helps confirm what had been intuitively ob- With lower levels of traffic generated from TODs, it can be vious: TOD housing produced considerably less traffic than argued that it simply makes no sense to construct roadway is generated by conventional development. Yet most TODs improvements for TOD related traffic that is not likely to are parked on the assumption that there is little difference materialize. between TOD and conventional development with respect Right-sizing new road and intersection improvements to to the traffic they generate. One likely result of this fallacious reflect the actual transportation performance can result in assumption is that fewer TOD projects get built. TOD de- more compact development patterns and a higher quality velopments that do get built are certainly less affordable and pedestrian environment since less land may be used for less sustainable than they might be because they are subject road improvements. to incorrect assumptions about generated traffic impact. Therefore many hoped for benefits (such as less time stuck Clear policy directions come from this research. The ap- in traffic and lower housing costs) from nearly $75 billion preciably lower trip-generation rates of transit-oriented in public dollars invested in rail transit (J. Neff, personal housing projects call for adjustments in the measurement e-mail, October 26, 2007) over the past 11 years are not being of traffic impacts. For peak periods (that often govern the realized. design of roads and highways), this research shows transit- One end result is that auto trip generation is likely to be oriented apartments average around one half the norm of overstated for TODs. This can mean TOD developers end up vehicle trips per dwelling unit. The rates varied, however, paying higher impact fees, proffers, and exactions than they from 70%-90% lower for projects near downtown to 15% should since such charges usually are tied to ITE rates. An- to 25% lower for complexes in low-density suburbs. Re- other implication of the research is that parking ratios for gardless, smart growth needs smart calculus; those who residential TODs also are likely to be overstated for TODs by build projects that reduce trips should be rewarded in the the same order of magnitude since they also are based on ITE form of reduced traffic impact fees and exactions. The ex- data. More research on parking generation will be needed to pectation is developers would pass on some of the cost

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55 savings to tenants, thus making housing near rail stations development approvals, better planned and more compact more affordable. communities, increased transit ridership, and more afford- To date, few jurisdictions have introduced sliding scale fee able housing. Tightening residential TOD parking ratios to structures to reflect the lowering of trip generation for TODs. reflect the actual transportation performance of TODs will be Santa Clara County California's Congestion Management a very important step toward realizing the expected commu- Agency has produced guidelines for a 9% trip reduction for nity benefits of TOD and enhancing their financial feasibil- housing within 2,000 feet of a light-rail or commuter-rail ity. In many TODs, the community and developer benefits station. While this is a positive step, according to our research have been understated because they have been over-parked. findings, this adjustment is a bit tepid. Similarly, the URBEMIS Additional research also is suggested to further address some software program sponsored by the California Air Resources of the questions addressed in the literature review. Board, used to estimate the air quality impacts of new devel- To help realize the benefits of TOD the team recommends opment, calls for up to a 15% lowering of trip rates for hous- the following: ing in settings with intensive transit servicesagain, likely on the low side based on these findings. More in line with the 1. Work with ITE and ULI to develop new trip generation findings presented here are the vehicle trip reductions granted and parking guidance for TOD. to the White Flint Metro Center project, a mega-scale, mixed- In the opinion of the authors, the highest priority should use joint development project being built at Washington, be placed on working with ITE and the ULI to develop and D.C. Metrorail's North Bethesda Station. With some 1.2 mil- implement new guidance on trip generation and parking lion square feet of office space, 250,000 square feet of for TOD housing. The research suggests developers are commercial-retail, and 375 residential units scheduled at being charged impact fees for non-existent trips and re- build out, the project was granted a 40% reduction in esti- quired to build expensive parking spaces that are not mated trip rates for the housing component based on prox- needed. Parking ratios developed using ITE trip generation imity to transit. rates over-park TODs by as much as 50%. In developing The trip reduction benefits of TOD call for other develop- new guidance on parking, it will be important to account ment incentives, like lower parking ratios, flexible parking for a variance in trip generation factors such as the quality codes, market-responsive zoning, streamlining the project of transit service and the distance of a station from the CBD. review and permitting process, and investments in support- The project team contacted ITE to share the panel's in- ive public infrastructure. Trip reduction also suggests TODs terest in working with ITE to develop new guidelines. In are strong markets for car-sharing. Recent research in the response, Lisa M. Fontana Tierney, P.E., Traffic Engineering San Francisco Bay Area reveals that those who participate in Senior Director ITE, commented, "Once the results of the carsharing lower their car ownership levels around 10%, with study are finalized and submitted to ITE, we will review higher vehicle-shedding rates among those living near rail the information and consider it for inclusion in a future stations (Cervero, Golub, and Nee, 2007). The combination ITE resource. Based on my understanding of the work, it of reducing off-street parking and increasing carsharing seems that it would be appropriate to consider the results options would yield other benefits, including reducing the of your study as part of a future edition of the ITE Trip amount of impervious surface (and thus water run-off and Generation Handbook. We expect to begin the update heat island effects) and the creation of more walkable scales process for this Handbook in early 2009." of development. Such practices are not heavy-handed plan- 2. Broadly disseminate the findings of this research. ning interventions but rather market-oriented responses, Benefits of TOD are muted since most TODs parking namely efforts to set design standards and provide mobility and traffic impacts assessments are oblivious to the fact options in keeping with the market preferences of those who that a rail stop is nearby. Broadly distributing results of the opt to live near rail transit stations. research can help lead to right-sizing TOD-housing regu- lations for parking and transportation impact fees and higher intensity of development appropriate for TODs. Recommendations With information in hand to confirm TOD housing With this research data to support the belief that people produces fewer trips than conventional development, it living in TODs drive less often than their neighbors in con- should be somewhat easier to get local approval to build ventional developments, public officials and government additional TODs without unnecessarily negotiating away regulators have the evidence needed to develop new, more the intensity of development envisioned in adopted realistic standards for assessing impact fees and mitigation for TOD plans. TODs. Developing residential TODs based on an accurate As an interim step, the findings of the research have assessment of their traffic impacts should result in easier been presented at the 2007 Rail~Volution Conference in

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56 Miami, Florida, the 2008 Congress for the New Urbanism uses have different annual peak parking demands, and Conference in Austin, Texas, and a transportation semi- how the annual peak parking demands differ from the nar at Portland State University. Findings also are slated to average daily demand. Parking utilization information be presented at the 2008 ITE Annual Conference in Ana- is needed for all TOD land uses. heim, California, and have been accepted for publication b. Research into self selection and change in travel pat- by the Journal of Public Transportation. terns after residents move into a TOD. A mode share The findings also will be shared with other researchers survey could be mailed to residents of selected TODs doing similar research, including the mixed-use trip and analyzed at a cost of approximately $3,500 per generation research being done at the Texas Transporta- TOD. The before and after study of Center Commons tion Institute and NCHRP Project 08-66, "Trip Genera- referenced in the literature review was done in this tion Rates for Transportation Impact Analysis of Infill manner. Development." c. Research on the impact of design features (e.g., mixed 3. Seek funding for additional research on TOD land uses. land-use, traffic calming, bus bulbs, short blocks, street The research presented here covers only one land use furniture), travel patterns, transit ridership, or the deci- type found in TODs. Additional research will be necessary sion to locate in a TOD. Intuitively we know "design to broaden the knowledge of the trip generation, the park- matters" but there is very little data to show the impact ing characteristics of TOD land uses, and the impact of of design on transit use, location decisions to live in a TOD on ensuring ridership in TODs. TOD or what design features have the greatest impact. The research needs identified by the team and the panel d. Research into what motivates employers to locate in flow from the field research, the literature review and the TODs. There is a growing body of information on res- state-of-the practice of what we know and don't know idential TODs and locational decisions. At the same about ensuring ridership from TOD: time, there is very little understanding how to impact retail and commercial locational decisions to be part of a. Research into the parking demand and trip generation a TOD. As a starting point, phone interviews of com- characteristics of office, retail, and mixed-use in TODs. mercial leasing agents and tenants in TODs could be This research also should consider the parking demands taken to distinguish the role TOD/transit may play in of the land uses and the degree to which different land locational decisions.