Exploration of the contributing factors to the walking and biking travel frequency using multi-level joint models with endogeneity

The enormous advantages of active transportation lead the transportation research focus towards enhancing the walking and biking trips. The present study explored the influential factors to the walking and biking travel frequency based on data obtained from the National Household Travel Survey California add-on survey. The study features some highlights. First, bivariate models were used to account for the common unobserved heterogeneity shared at both household and personal levels. Second, endogeneity was explicitly considered. Third, both variable importance ranking and correlation analysis are employed to determine the different features to be fed into each of the joint models. The results illustrated that the models developed with endogeneity performed better than the models without endogeneity. Four influential variables which includes mode to work by bicycle, public transit usage, count of household members, and multiple race responses, tend to have statistically significant impacts on walking and biking trips.