Revisit employer-based travel demand management: A longitudinal analysis

Employer-based travel demand management (TDM) programs have been implemented worldwide for decades, but rarely are longitudinal analyses implemented. This study utilizes a longitudinal dataset to assess the effectiveness of TDM measures on vehicle trip rates (VTRs) over time. The results suggest: (1) VTR grows over time, and TDM measures may decelerate the growth but cannot reverse the trend; (2) for organizational tools, collective bargaining is negatively associated with VTR; (3) distributing transit passes is negatively associated with VTR; (4) ride match is positively correlated with VTR; (5) guaranteed ride home measures, including emergency rides and employer-provided vehicles, are positively associated with VTR; (6) subsidies promoting multimodal transportation (transit, walking, biking) incentivize vehicle trip reduction; the more subsidies, the lower VTR, and such effects are reinforced over time; (7) in contrast, subsidies promoting carsharing are associated with more vehicle trips; (8) larger companies and areas with higher job densities have a lower VTR. To inform practice, when rewarding employees, distributing transit passes is a preferred strategy. Collective bargaining builds agreements between employers and employees and helps promote trip reduction. Carpooling-related and guaranteed ride-home measures should be applied with caution.