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Table 17-37 Household Characteristics of California Station-Area Office Workers Characteristics TOD Sites Surrounding City Percentage Distribution of Household Size 12 persons 54.3% 55.4% 34 persons 37.6 30.6 5+ persons 8.0 14.0 Percentage Distribution of Household Income $30,000 or less 8.6% 29.0% $30,001 to $60,000 35.5 29.7 $60,001 to $150,000 50.2 34.1 Over $150,000 5.6 7.2 Percentage Distribution of Occupations Office/professional 92.1% 35.2% Craftsman/laborer 1.1 18.0 Sales service 5.6 38.6 Other 1.1 2.3 Note: Surrounding city figures are based on 2000 Census. Source: Lund, Cervero, and Willson (2004a). A projection of "potential demand" for smaller, compact housing near transit--as contrasted to "actual demand" affected by such factors as prices--has been prepared for the U.S. Federal Transit Administration. The projection was derived using demographic trends, consumer preference assumptions, and capture rates applied separately by metropolitan region and transit zone type. In the year 2000, a total of 6.2 million households lived within 1/2 mile of existing urban rail stations, representing 12 percent of the total population in the 27 regions examined. The analysis results indicate that by 2025 over 14.8 million households nationwide could want housing within 1/2 mile of rail stations on existing systems and 15 extensions or new systems. Of the potential 2025 demand, 64 percent was projected to consist of singles and couples without children, 15 per- cent other households without children, 12 percent married couples with children, and 9 percent single parents and other households with children. Disproportionately high representation by households headed by persons aged 65 or older was forecast, as was disproportionately low representation by the mid-age group. The projected household age group representation was 35 percent in the 65+ age category, 42 percent in the 35 to 64 category, and 23 percent in the age 15 to 34 category (Center for Transit-Oriented Development, 2004). Trip Characteristics and Congestion TOD typically features higher-density development, leading to greater concentrations of residents, workers, or shoppers in a localized area than otherwise would occur--especially in suburban contexts. It is also a reality, in most instances, that the majority of travelers will use automobiles to access the development. Obviously this combination of factors may lead to congestion. Mitigating against such an outcome is the higher transit ridership associated 17-83

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with TOD. Also, some trips that would otherwise require an auto may be replaced with internal walking trips, at least to the extent the TOD offers an appropriate mix of uses and a good walking environment. The relevant, interrelated topics of TOD trip generation, trip chaining, midday trip making, and congestion are examined here. Trip Generation Trip generation can be viewed from either a person trip perspective or a vehicle trip perspective. Development planners tend to adopt the latter perspective. There is at the present time no TOD equivalent of the generally accepted Institute of Transportation Engineers (ITE) vehicle trip generation rates for stand-alone suburban development, nor is there an equivalent for mixed-use, pedestrian-oriented development in general (Millard-Ball and Siegman, 2006). Individual entities have developed procedures to follow ITE recommendations that the ITE average trip generation rates be adjusted for reduced automobile use in environments with substantial transit use and other vehicle-trip-reducing features. These procedures draw upon the available trip-reduction literature to estimate suggested adjustments. One such procedure developed for California air pollution control districts facilitates estimation of trip-reduction adjustments for residential density, mix of uses, local-serving retail, transit service, pedestrian/bicycle friendliness, affordable housing, and selected TDM measures including parking supply and pricing (Nelson\Nygaard, 2005). A student research project that focused directly on both vehicle trip and non-automotive person trip generation at eight residential projects adjacent to transit in Portland, Oregon, is reported on in the case study, "Travel Findings for Individual Portland, Oregon, Area TODs." The research found evidence of generally lower vehicle trip generation than unadjusted ITE trip generation rates for stand-alone development, although there was wide variation from development to develop- ment (Lapham, 2001). Findings such as these and studies for mixed use developments in general align with the practice of some planning agencies of offering credit or reductions in standard vehi- cle trip generation rates for TOD roadway infrastructure planning (Millard-Ball and Siegman, 2006; Nelson\Nygaard, 2005). Lower vehicle trip generation rates translate into the possibility of more development per given amount of allowable traffic than for non-TOD development with its standard rates for trip generation. An example is provided by the planning of the White Flint Metro development in Montgomery County, Maryland, outside Washington, DC. This 34-acre mixed-use project at a Metrorail heavy rail transit (HRT) station was granted a 45 percent reduction in estimated vehicle trip generation rates as follows: mixed-use credit--10 to 25 percent; proximity to transit credits--40 percent for apartments, 50 percent (AM peak) to 28 percent (PM peak) for offices, 25 percent for retail, and 5 percent for cinema; and traffic management credit--10 to 23 percent. At build-out the project is to consist of 1.2 million square feet of office, 212,000 square feet of retail, and 1,400 high-rise apart- ments (Cervero et al., 2004). The lower reductions offered for the retail uses are consistent with findings and treatment elsewhere. Mode share differentials relative to non-TOD areas, especially in the suburbs, are the dominant factor allowing lower vehicle trip generation rates. Nevertheless, auto use remains substantial for both work and non-work purpose trips. The 2003 California TOD travel characteristics study found that, overall, 88 percent of non-work trips made by station-area residents were made in an automobile as compared to 72 percent of work trips. Auto ridesharing was more common for non-work trips, however. Transit was used for 8 percent 17-84

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and walking for 4 percent of non-work trips and 26 and 1 percent, respectively, of work trips (see Table 17-17). The reported trip purpose distribution for non-work trips by station-area residents was 26 percent shopping, 17 percent meal or snack, 9 percent transporting children, 17 percent other errands, and 30 percent social or recreation. The transit mode share varied depending on the stated purpose of the non-work trip. Table 17-38 provides a mode share summary that includes both work and non-work travel (Lund, Cervero, and Willson, 2004a). Table 17-38 Mode Shares by Trip Purpose for Station-Area Residents in California Pick up, Meal or Drop off Other Social, Travel Mode Work Shopping Snack Children Errands Recreation Drove (alone) 66.4% 55.6% 55.6% 58.3% 72.8% 62.6% Carpool 5.3 29.0 33.3 31.7 22.8 18.6 Rail Transit 24.3 4.1 2.8 0.0 1.8 10.1 Bus Transit 2.2 3.6 3.7 6.7 0.9 2.5 Bicycled 0.6 0.0 0.9 0.0 0.0 1.5 Walked 1.3 7.7 3.7 3.3 1.8 2.5 Took Taxi 0.0 0.0 0.0 0.0 0.0 2.0 Number of trips 877 169 108 60 114 198 Note: Based on surveys of residents of 26 California station-area projects. Source: Lund, Cervero, and Willson (2004a). Trip Chaining Trips requiring an intermediate stop are more difficult to conduct using transit. Looking at findings from the 2003 California TOD travel characteristics study for all trip purposes, station- area residents were much less likely to use transit for trips that included an intermediate stop. Transit was used for only 10.7 percent of chained trips compared to 25.7 percent of non-chained trips. The binomial-logit model of station-area resident transit choice developed by the researchers also reflected the negative influence of trip chains on transit usage propensity (see Table 17-30). The researchers found 25.4 percent of non-work trips made by station-area residents to involve a chain of several non-work activities and 15.1 percent of work trips to involve intermediate stops between home and work or vice versa. Intermediate stops on commute trips by station area residents were for meal or snack (24 percent), shopping (21 percent), and transporting children (16 percent). Station-area employees were more than twice as likely as station-area residents to report intermediate stops during a commute trip. Intermediate trips were reported by 35.2 percent of employees. This higher rate could be because station-area workers may have driven to access their origin transit station and thereby be able to easily make intermediate stops on the auto access portion of their trip, whereas station-area residents are likely to walk to their origin transit station. TOD development has the potential to address the need for at least some of these 17-85

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intermediate stops if the appropriate mix of uses and good walking connections is present, either for residents or workers (Lund, Cervero, and Willson, 2004a). Midday Trips TOD offers the potential for substitution of walking, and perhaps transit trips, for midday auto- mobile trips. Midday trips made by station-area workers surveyed in the 2003 California TOD travel characteristics study were for the following trip purposes: meal or snack (48 percent), business-related (21 percent), shopping (14 percent), and other (17 percent). Midday mode shares varied, with an overall average of 56.7 percent walk mode share as compared to 39.5 percent auto- mobile. Only 2.7 percent of midday trips made by station-area office workers were by either bus or rail transit, however. This outcome may in part be a reflection of the deterrent represented by the working or lunch break time that would have to be dedicated to waiting for a transit vehicle to arrive. Midday mode shares around specific groups of California stations were previously pro- vided, in Table 17-18. Particularly in comparison to stand-alone non-TOD suburban development, mixed-use TOD appears to offer significant opportunities for midday workplace-related vehicle trip reduction (Lund, Cervero, and Willson, 2004a). Station area employee survey information from the Washington, DC, region paints a similar pic- ture with regard to vehicle trip reduction potential, but with midday travel via transit a much big- ger factor than reported for California. Washington station-area office worker midday trip mode shares range from a low of 16 percent Metrorail and 3 percent bus for trips for meals or snacks to 36 percent Metrorail and 9 percent bus for education-purpose trips (WMATA, 2006a). Possible explanations for the California versus Washington-region transit-share contrast may be structural differences between the urban geographies studied in California and Washington and lower HRT, LRT, and CRR service frequencies in California as compared to higher Washington Metrorail HRT frequencies. Mode shares for the full array of midday trip purposes surveyed in Washington were presented earlier in Table 17-13. Congestion While TOD has been shown to have higher non-automobile mode shares than traditional subur- ban development, it is not fully clear how this translates into regional impacts or degree of increased localized congestion. On balance, TOD would appear to offer regional travel benefits, especially in terms of making transit investments more productive. In addition, a general rela- tionship between the presence of land use characteristics similar to those found with TOD and reduced household daily vehicle miles of travel has been observed. See, for example, the case study, "Baltimore Region TOD and Smart Growth Analysis." The concentration of activities associated with TOD brings potential, however, for local area congestion. Concerns about traffic associated with TOD have been a factor in shaping the ultimate size and scale of projects. Ultimately, many communities have determined that some level of congestion can be accepted and that there may be some trade-offs when creating TOD. Examples of TOD clearly exist, for example in Arlington, Virginia, where development density was greatly increased without incurring paralyzing automobile traffic levels (Cervero et al., 2004). For more on Arlington's experience see "Response by TOD Dimension and Strategy"--"Response to TOD by Primary Transit Mode"--"Heavy Rail Transit." 17-86