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19 internal capture rates, and (2) lower regional accessibility re- A survey of TND residents found that TND households sulted in higher internal trip capture. This finding is rele- made about the same number of total trips, but made fewer vant when considering the relative attraction of an internal automobile trips and fewer trips external to the site when complimentary use destination given access to similar off- compared with households in the conventional neighbor- site opportunities of a similar type. According to this study, hood. A survey of the TND businesses found that 5.2% of easy access to regional areas decreases the attraction of ful- the employees live within the TND, 39.2% of the business filling several trip purposes without increasing trips on non- customers/visitors live in the TND, and 18.1% of trips to internal roadways. TND businesses are by walking. Rutherford et al. found that in multi-use neighborhoods, Based on the survey results and vehicle counts taken at the the total number of trips were about the same as for subur- neighborhood access points, the study estimated 20.2% inter- ban single-use neighborhoods but walk trips accounted for nal capture of all trips made to or from businesses and house- about 8% more of the total trips (33). Vehicle availability holds within the TND. The comparable surveys and counts did not seem to be a factor, but higher household income at the conventional neighborhood measured 5.5% internal was associated with fewer walking trips. Over 70% of the capture. The study postulated that the difference in internal walking trips were 1/2 mile or less, and about 40% were less capture (14.7%) is the product of the TND mixing of uses than 1/4 mile. Less than 10% were over a mile. This confirms and spatial characteristics. the importance of proximity and walkability in internaliz- ing trips. Other Related Findings Gordon and Peers note in their research on pedestrian design for a mixed-use community in Sacramento County One of the trip characteristics that may be needed to esti- (Laguna West) that based on the correlation that the National mate internal trip capture is trip purpose. The International Resources Defense Council has established between urban Council of Shopping Centers conducted surveys in 2003 to ob- density and automobile usage, this development may have a tain detailed information on typical office worker lunchtime reduction in VMT on the order of 20% to 25% (15, p. 144). activities and shopping habits during and after the workday Furthermore, they noted that the job capture rate in this area (37). Based on about 500 completed interviews in both subur- averaged between 15% to 20% of local residents holding jobs ban and downtown locations, retail density is not a crucial fac- internal to the area, thus reducing trips and increasing the tor: employee mode of transportation was more important, potential for walking (15, pp. 144145). with driving employees spending nearly 30% more per week A 2003 cordon count of Celebration, Florida--a 10-year-old, on each category (shopping, food, and convenience items). On self-contained MXD of 3,500 developable acres--compared average, office workers bought lunch outside their offices three a three-weekday cordon traffic count to estimated trip gen- out of five days a week (more often downtown than in sub- eration for development existing at that time based on ITE urbs). Some 62% shopped before, during, or after work at least trip generation rates. The comparison indicated that actual once a week (slightly more in suburban office locations), with daily external trips were 27.7% less than ITEbased estimates. an average of 2.6 shopping trips per week. Office workers were P.M. peak-hour counts were 31.8% less than ITEbased reported to make about twice as many shopping trips close to estimates (34). home than close to work. Of their shopping expenditures, al- When analyzing the impact of smart growth site design most 60% were on dry goods and about 40% on convenience using a travel modeling process for a project in Atlanta, items. In addition, 32% of respondents socialize after work at Walters, Ewing, and Schroeer suggested that good site design least once per week with most stopping one or two times dur- using TOD and MXD principles conservatively resulted in a ing the week. Those stopping after work for food and drinks 14% to 52% reduction in travel. This evaluation utilized were about twice more likely to stop closer to home than closer INDEX software in the modeling process, which is discussed to work. later in this chapter (35). TCRP Report 95, Chapter 15: Land Use and Site Design, A study was conducted to compare trip-making character- Traveler Response to Transportation System Changes contains istics between a traditional neighborhood development (TND) information related to analyzing transit ridership and other in Chapel Hill, North Carolina (Southern Village) and a con- travel relationships to land use and site design features (38). ventional residential neighborhood in Carrboro, North Car- This report is a compilation of a large number of sources, olina (36). The TND was comprised of 920 occupied dwelling some of which are related to internal trip capture. units (611 single-family, 197 apartments, and 112 condomini- This report concluded that transit mode choice and ridership ums); 30,000 sq ft of retail (including a 5,800sq ft grocery are highly related to development density if it is coupled with a store and a four-screen movie theater); 95,000 sq ft of office; higher level of transit service. Density alone is not enough (38, a 90,000sq ft elementary school (with 606 students); a p. 15-10). Similarly, non-motorized travel (primarily walking 6,000sq ft daycare center; and a 27,000sq ft church. and biking) increases with density, but in conjunction with

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20 more land use mixing, compactness involving interacting uses, density, but (1) those elasticities reflect other urban area con- and pedestrian connections. This report concluded that density ditions and (2) the elasticities are derived from regional travel was not found to be significant by itself in some cases. This forecasting zonal databases and may not be directly transfer- report also reports more walking in traditional neighborhoods able for this internal trip capture research (38, p. 15-23). The (mixed use) than in late 20th-century planned unit develop- same report shows that good pedestrian environment and ments. This report also contains a finding that transit rider- transit versus bad results in about 21% less trips per house- ship declines with distance of housing to transit, falling 1% hold and 46% less household VMT (38, p. 15-28). to 2% per 100-ft increase in walking distance (38, p. 15-31). TCRP Report 95, Chapter 15 also examined the relationship A California DOT (Caltrans) funded study confirmed between jobs/housing balance and trip making. Most find- that residential density is insignificant (correlation -0.025) ings showed significantly better balance results in shorter in affecting transit ridership within a 1-mile radius of a tran- trips, but not fewer trips (38, p. 15-41). The quantified results sit station (36). Street connectivity was found to have the reported in this report varied widely, but one finding was that highest correlation (+0.373). Walking distance to the transit the "best new communities in the United States" are estimated station was found to have a significant affect, as Figure 1 to achieve 31% to 37% internal commutes (38, p. 15-41). Job shows. The number of walking conflicts is more influential balance was also reported to result in employees taking jobs (0.11 correlation) as is presence of sidewalks on one or closer to home, although the quantification relates to inside both sides of the street (+0.171 and +0.150, respectively). or outside city of residence rather than distance per se (38, That research concluded that sidewalk width, landscaping, pp. 15-44 through 15-45). The same report indicates that and number of intersections have insignificant influence on land use balance/mix has an elasticity of -0.10 related to transit ridership. household VMT and that land use balance/mix has an elas- TCRP Report 95, Chapter 15 also reports that vehicle trip ticity of +0.23 related to walk/bike trip elasticity (38, pp. 15-47 generation is 1% to 3% less when improved pedestrian access through 15-51). Another source quoted in this report indi- is provided at regional shopping centers and 6% to 8% less cates that local land use balance/diversity has an elasticity of for office employee vehicle trips at the edge city office build- 0.03 related to vehicle trips (38, p. 15-48). ings containing retail (38, p. 15-12). This source also reported The same report contains information on residence and that Steiner found decreased vehicle use in higher-density shopping land use mix in traditional neighborhoods--those residential areas because of closeness, safety in numbers, and with shopping in or adjacent to and well connected with hous- attraction of supportive lifestyles that support walking (38, ing areas. Table 22 shows the relationship between the percent- p. 15-18). The report contains elasticities of -0.10 for total age of survey respondents living within 1/2 mile of shopping and VMT related to density and -0.05 for vehicle trips related to the number who reported walking to shop (38, pp. 15-52 Source: 39, p. 101. Figure 1. Percentage of transit commutes by walking distance from station.

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21 Table 22. Comparison of shoppers who walk to shopping with percentage of residents within one-half mile of shopping. Residents Living Percent Walking Trips Traditional Shopping Area within 1/2 Mile of Shopping Area Weekday Saturday Rockridge--Market Hall (full array, restaurants) 24% 26% 28% Rockridge--Alcatraz (grocery, specialty) 40% 38% 41% Elmwood (convenience, specialty) 33% 28% 36% El Cerrito Plaza (full array) 12% 10% 10% Hopkins Specialty (food) 32% 23% 29% Kensington (convenience, services) 58% 20% 27% All Areas 32% 24% 28% through 15-53). This table shows a very close relationship than normal. The same source reported vehicle occupancy between residential location and the percentage of residents rates for 1 millionsq ft office buildings averaged 0.8 more who walk. passengers per work trip than for buildings half that size (38, Hooper showed in activity center surveys that an inte- p. 15-62). For activity centers with major office concentra- grated development--the Dallas Galleria--had a midday tions, for every 10% addition of retail or commercial uses, walking trip share of 17% while other suburban activity cen- there was a 3% increase in non-single occupant vehicle com- ters with nearby, but mostly auto-accessible, complementary muting (+0.30 elasticity) (38, p. 15-64). Similarly, it was re- uses had walk shares of only 2% to 7% (38, p. 15-61). ported for Seattle that walking is about twice as prevalent in TCRP Report 95, Chapter 15 reports that land use mix in mixed-use neighborhoods than for suburban-type neighbor- activity centers reduce midday vehicle shares, at least to major hoods, although walk percentages varied by location in the retail, and that land use mix influences choice of vehicle or region (38, p. 15-72). walk access, with greater mix associated with less vehicle use The same report shows that household income has more and more walk access (but not transit access) (38, p. 15-55). effect on mode choice and on total trips per household than Another researcher found that vehicle trip generation rates at does whether the development is a traditional or conven- office buildings in suburban activity centers were 6% to 8% tional suburban neighborhood (38, p. 15-78). Table 23 shows lower than normal and transit trips were about 3% higher results of a survey in Orange County, California. Similar walk Table 23. Trip rates and mode share in different neighborhood types, Orange County, California. Neighborhood Type Traditional Travel Parameter Income Planned unit neighborhood All types development development Low 6.4 7.2 6.5 Mean daily trips per Medium 8.8 10.7 9.9 household High 10.8 12.3 12.5 All 8.2 10.9 9.6 Low 5.1 6.6 5.6 Mean daily vehicle Medium 8.0 9.7 8.8 trips per household High 10.2 11.3 11.6 All 7.0 9.8 8.5 Low 80% 91% 86% Medium 91% 91% 90% Percent by vehicle High 94% 92% 92% All 86% 91% 89% Low 6% 3% 3% Medium 2% 2% 2% Percent by transit High 1% 1% 15 All 4% 3% 3% Low 15% 11% 11% Medium 7% 7% 7% Percent by walk High 5% 7% 7% All 9% 8% 8%