At the time of publication J.Y. Guo was at the University of Wisconsin-Madison; and C.R. Bhat and R.B. Copperman were at the University of Texas at Austin.It has become well recognized that non-motorized transportation is beneficial to a community's health as well as its transportation system performance. In view of the limited public resources available for improving public health and/or transportation, the present study aims to (a) assess the expected impact of built environment improvements on the substitutive, complementary, or synergistic use of motorized and non-motorized modes; and (b) examine how the effects of built environment improvements differ for different population groups and for different travel purposes. The bivariate ordered probit models estimated in this study suggest that few built environment factors lead to the substitution of motorized mode use by non-motorized mode use. Rather, factors such as increased bikeway density and street network connectivity have the potential of promoting more non-motorized travel to supplement individuals' existing motorized trips. Meanwhile, the heterogeneity found in individuals' responsiveness to built environment factors indicates that built environment improvements need to be sensitive to the local residents' characteristics.Civil, Architectural, and Environmental Engineerin
