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to assist the reader in assessing what is less or more reliable. These notes range from informa- tion on survey and analysis conduct--for the reader to weigh--to outright questioning or confirmation of likely reliability. Traveler Response Summary TOD concentrates trip generation and attraction around transit stops and stations resulting in more transit ridership per stop, even if one makes the hypothetical assumption that TOD transit mode shares are no higher than produced by conventional development in the same locations. Typically, however, the special attributes of well-designed TOD result in transit shares that are higher--and automobile mode shares that are lower--than for non-TOD. This outcome leads to even further elevation of transit ridership levels. With regard to vehicular traffic volumes, the extent to which TOD travel concentrations may result in more local area automobile travel in total depends on the degree of concentration on the one hand and the success in achieving lower auto driver mode shares on the other. Numerical examples of actual transit ridership gains that can be clearly attributed to TOD imple- mentation are few because of the many sources of ridership and multiple confounding factors typically present. One station where TOD or equivalent development is fairly clearly the primary cause of ridership gains is Gallery Place in the old downtown of Washington, DC. Weekday Metrorail boardings at the station grew from 6,500 in 1997 to 10,200 one year later with construction of a transit- oriented sports arena. By 2002, weekday boardings stood at 13,800 after a half-decade of TOD-like redevelopment in the area. An analysis of TOD across the Potomac in Arlington, Virginia, found each 1,000 additional dwelling units together with the effects of Metrorail service increases was associated with 500 new boardings/alightings (roughly 250 boardings and 250 alightings). Similarly, each 1,000 square feet of office/commercial space was estimated to be associated with nearly 500 new boardings/alightings. On a smaller scale, weekday boardings at the Downtown Plano LRT station in the Dallas suburbs--a station with no park-and-ride spaces--grew from 590 riders in 2003 to 770 in 2006 concurrently with construction and occupancy of nearby TOD. The difficulty of ascribing ridership changes directly to TOD is illustrated by the circumstance that the station's 31 percent 3-year growth was bracketed by the 21 and 38 percent 3-year growth experienced at the adjacent auto-oriented stations with no TOD. TODs may be categorized according to regional context, land use mix, and primary transit mode. A broad variety of factors appear to influence the traveler response to TOD including land use and site design, automobile ownership, relative transit and highway accessibility, parking supply, parking pricing, transit support, and evidently self-selection of residents as well. It also appears that the various influences on TOD travel behavior choices are decidedly interactive in nature. These factors are not all transportation-related, suggesting that it takes more than good transportation policy alone to develop high-quality and effective TOD. Density, diversity, and design influence TOD impacts in much the same way that they impact non-TOD land development. Higher densities, greater diversity of land uses, and better design are associated with more transit use and walking and fewer automobile trips per resident and per worker. TOD also facilitates accomplishment of activities within the devel- 17-6

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opment itself, on foot or via convenient transit connection, thereby eliminating the need for some automobile trips and helping make auto commuting less of a necessity. In Portland, Oregon, as of 1995, the average central area TOD transit share for non-work travel was roughly four times the transit mode share for outlying TODs, which in turn had over one-and-two- thirds times the corresponding transit share of mostly-suburban, non-TOD land development. The walk and bike non-work central area TOD share for trips produced at the residence was two-and- one-half times the share for suburban TODs (but essentially equal for trips attracted to commerce and other activities), while suburban TODs had roughly twice the walk/bike share of non-TOD areas. The auto mode share for trips produced at the residence in downtown TODs was 70 percent of the comparable share at suburban TODs, and the suburban TOD auto share was approximately 90 percent of the non-TOD auto share. The influence of socio-economic factors relative to land use design in producing these effects has not been quantified. Similar data for Portland work-purpose trips have not been developed. Station-area surveys made in the Washington, DC, region in 2005 show, however, that work-commute transit mode shares decline from 75 percent at downtown office buildings right at Metrorail stations to just over 10 per- cent on average at office buildings within roughly 1/2-mile of a station but located in the suburbs outside of the Capital Beltway. All reported trips by residents of selected residential sites near sta- tions range from an average of 56 percent transit in the downtown to 32 percent transit beyond the Beltway. Whatever the location within the region, however, transit shares were found to increase markedly with closeness to a Metrorail station, a phenomenon also found around rail stations in Chicago, California, and Canada. Transit mode shares along the Washington Metro system were found to decrease by 7 percentage points for every 1,000 feet of distance from a station in the case of housing and by 12 percentage points in the case of office worker commute trips.1 A 2003 California TOD travel characteristics study found TOD office workers within 1/2 mile of rail transit stations to have transit commute shares averaging 19 percent as compared to 5 percent regionwide. For residents, the statewide average transit share for TODs within 1/2 mile of the station was 27 percent compared to 7 per- cent for residences between 1/2 mile and 3 miles of the station. Along Northern California's BART system, the two sets of HRT TODs reported on had in one case a 38 percent commute trip transit share within 1/2 mile versus a 3 percent share between 1/2 mile and 3 miles, and in the other case a 45 percent share versus 13 percent. The one set of California CRR TODs separately examined showed a 17 percent commute trip transit share within 1/2 mile versus a 5 percent share for areas between 1/2 and 3 miles. The two sets of LRT TODs examined had 13 percent versus 6 percent transit commute shares in one case but 3 percent versus 11 percent (the reverse of that expected) in the other. In the instance where transit commuting was less prevalent within the TOD than further from the station, survey responses on reasons for residential location choice suggested that non-transit attractions of the housing (cost and quality) had overwhelmed and rendered moot the transit service benefits offered, an unusual but apparently not totally unique situation. Quantitative information on BRT and other bus-oriented TODs is extremely limited, but clearly BRT service parameters are comparable to those of many LRT systems. Circa 1990 1 "Percentage points" refers to an absolute difference in percentages, rather than a relative difference. 17-7

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peak period transit mode shares at major mixed-use neighborhoods and universities along Ottawa, Canada's busway system, for all trip purposes combined, averaged 52 percent transit at three loca- tions directly served by BRT stations and 34 percent at two off-line locations. Over 90 percent of station-area TOD residents surveyed in the 2003 California study reached their neighborhood rail station by walking, a major vehicle trip reduction and air quality enhancement benefit. The greater the concentration of transit trip generation within station areas, the higher a station's overall walk access share will tend to be. For example, with the high TOD development densities along Arlington, Virginia's Ballston corridor, the Ballston Metrorail station achieved a 67 percent walk access share in 2002 for the 22,000 daily station entries and exits. Chicago area walk access shares for six high ridership Metra CRR stations reported in 2000 were 82 percent at up to 0.5 miles (TOD territory), 41 percent at 0.5 to 1.0 miles, 8 percent at 1.0 to 2.0 miles, and 1 percent at over 2.0 miles. Corresponding drive alone access shares were 8, 33, 53, and 64 percent with increasing distance from the stations. TOD residents are generally associated with lower automobile ownership rates. Reduced auto- mobile availability is important to TOD impact--residents or workers without access to an auto- mobile are more likely to forgo travel or to make trips on foot or by transit. Auto ownership in three New Jersey "Transit Village Areas," for example, averaged 1.8 vehicles per household compared to 2.1 outside the transit villages. Corresponding users of transit (at least 10 times per month) rep- resented 25 percent of households inside the transit villages and somewhat over 15 percent of households outside. Supportive policy or planning actions may be able to reduce auto ownership rates further still at certain TODs, achieving additional automobile mode share reduction as a result, or may be able to directly enhance use of alternatives to the auto. The 2003 California study found, for example, that among surveyed workers in TODs the work trip transit mode share was 25 percent for those receiv- ing an employer transit subsidy and 5 percent for workers without this benefit. It is a reasonable but only anecdotally-supported speculation that offering pass programs packaged with residence purchase options or rents may be a useful device for attracting low-auto-ownership, transit-using residents to TODs lacking the advantage of heavy-duty transit services fully competitive with the auto. Relative transit and highway accessibility exert important influences on TOD impacts. The frequent, highly connective transit service associated with most TOD offers a better alternative to automobile usage than the lesser transit service associated with more typical low-density development. Competitive transit travel times and short waiting times are important contributors to transit usage in TODs, just as they are outside the context of TOD. Parking management is also key to TOD traveler response. In the 2003 California study, surveyed TOD office workers were over three times as likely to use transit where parking availability was less than one parking space per two workers as compared to offices with more parking. (Factors other than parking supply alone were undoubtedly at play.) Constrained and priced parking may lead to lower park-and-ride ridership but potentially higher transit mode shares for the development within the TOD. TODs provide a number of parking efficiencies including reduced parking needs and shared parking opportunities. A TOD relationship that is quite poorly established at present is the degree to which TOD can reduce vehicle trips and vehicle miles of travel (VMT) from a regional perspective. The seemingly ideal measure would be the change in travel choices made by individual TOD 17-8

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residents when they move and settle in. Only four studies were encountered that provide comprehensive observations in terms of mode share changes made by TOD or other station-area residents, with three of these offering published quantification of overall net changes. The documented and inferred travel mode shifts upon relocation into TODs range from 2 percentage- point or smaller shifts into the transit mode for commuting (average of surveyed California sites, two statewide studies) to 15 or 16 percentage-point shifts to transit commuting (two Portland, Oregon, studies, one providing an 8-site average). The Portland results must be taken in context with Portland's highly transit-supportive conditions and medium-sized urban area environment and pertain only to LRT-based TODs. In California, the shifts were larger and more clearly beneficial for the survey subset of residents along the BART HRT system as compared to TOD survey respondents statewide. Taken together with shifts in and out of walk, bicycle, and other modes, the apparent effect on automobile commuting ranged from indiscernibly small effects on average across surveyed California residential sites to an 18 percentage-point drop in auto use found in the 8-site Portland survey. Faced with the uncertainties introduced by this sparse data, reliance must also be placed on mode share comparisons between TODs and non-TOD areas such as those presented earlier in this summary. One of the most clear-cut transportation benefits of TODs is the positioning of large numbers of transit riders close enough to their transit stop that they can and will walk to it in pref- erence to auto use for the access mode. Some reviewers of TOD efficacy have postulated that the higher transit mode shares normally observed in TODs may simply result from attraction of "transit-oriented" residents to TOD hous- ing and that the outcome may be a lack of significant increase in transit use when viewed from a region-wide perspective. This overall hypothesis has received the somewhat confusing "self-selection" short-hand labeling. Survey findings do indicate that modest proportions of TOD residents have indeed made their housing choice with the good TOD transit use opportunities as one of their top reasons. For there to be no increase in regional transit use, however, the transit usage of such indi- viduals must--on average--not change overall. Recent research on the interplay between attitudes and travel choices does not appear to support the likelihood of this part of the proposition. The new research indicates that there are actually greater differences between the travel choices of "urban-oriented" residents of conventional suburbs and similarly inclined persons residing in TOD-like traditional city neighborhoods than there are between the travel choices of "suburban- oriented" residents located in one or the other of these two disparate environments. The cause appears to be inability of urban-oriented residents to act on their preferences and make much practical use of transit and walking within conventional suburbs, whereas it remains inherently feasible for suburban-oriented residents to choose to drive even in highly urban environments. The logical conclusion from this finding is that "transit-oriented" residents should not be written off as persons who will use transit and walk with or without TOD benefits--they may well be the ones who respond most enthusiastically with shifts away from auto travel when provided with the realistic transit use and walking options that effective TOD offers. Under these circumstances, TOD resident self-selection could actually be a positive force in reducing regional auto travel and enhancing transit ridership. Suggested values for essential indicators of a "TOD Index" to describe development project "TOD- ness" (see also Tables 17-44 and 17-45) include: Centrally located transit with walking distances no more than 1/4 to 1/2 mile. 17-9