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The recent research on interplay between attitudes and travel choices, summarized in the "Self- Selection of Residents"--"Self-Selection Effects on TOD Regional Travel Impacts" subsection at the end of the "Underlying Traveler Response Factors" section, also contributes to understanding of VMT reduction potential. Urban-oriented residents of a TOD-like traditional urban neighbor- hood were found to produce 46 percent less VMT than urban-oriented residents of suburban neighborhoods, while suburban-oriented residents of the urban neighborhood produced 38 per- cent less VMT than suburban-oriented suburbanites (Schwanen and Mokhtarian, 2005b). Caution must be used in extrapolating from these findings, however, as they speak primarily to urban TOD relative to conventional suburbs and would undoubtedly overstate the achievable VMT reduction if applied to suburban TOD. TOD can contribute to energy efficiency and pollution reduction to the extent that it leads to vehicle trip and VMT reductions. The degree to which TOD is able to reduce VMT is dependent on the underlying travel response factors covered earlier: pre- versus post-TOD travel modes effects as presented in the preceding subsection, and the VMT implications as discussed above. The evidence is particularly compelling, although not complete, that TOD favorably impacts the mode of access for transit trips, reducing the proportion of auto access. Since short drive-to-transit trips can generate nearly as much pollution as longer drive-to-destination trips, conversion of drive-to-transit trips to walk-to-transit trips may have significant air quality benefits. A California Air Resource Board study estimated a 20 to 30 percent reduction in VMT for TOD households as compared with non-TOD households and a corresponding reduction in CO2 emissions of 2.5 to 3.7 tons per household per year (Parker et al., 2002). TOD can also have energy and environmental benefits in terms of housing and workplace efficiency improvements. TOD uses less land than comparable standard development. Suburban TOD dwelling units and offices may be smaller than in standard suburban spaces, and smaller spaces are generally more energy efficient. In any case, the party walls, multi-family dwellings, and multi-story offices typical of TOD are, in general, more energy efficient than a series of single- family dwellings or one-story buildings because of lesser exterior heat loss areas per dwelling unit or employee (Newman and Kenworthy, 1999). Health and Safety Benefits A variety of health and safety benefits can logically be ascribed to TOD, falling in three main categories: health benefits attributable to increased walking opportunities, health benefits from improved regional air quality, and safety benefits deriving from an improved pedestrian environment. More findings on the subject of pedestrian improvements and health and safety benefits are presented in Chapter 16, "Pedestrian and Bicycle Facilities." Within Chapter 16 see "Health Relationships and Benefits" and "Safety Issues and Experience" under "Related Information and Impacts." While cataloging the health and safety impacts of TOD is beyond the scope of this chapter, it is useful to note that they likely exist. Compact development in general increases opportunities for walking. To the extent that TOD creates more opportunities for walking it can contribute to a healthier lifestyle. A 2003 study looked at the correlation between a sprawl index and the body mass index for 448 counties in urban areas across the United States. It found that people in more sprawling counties were likely to walk less and weigh more than people living in less sprawling 17-95