Citywide Effects of High-Occupancy Vehicle Restrictions: Evidence from the Elimination of ‘3-in-1’ in Jakarta

In cities worldwide, the widespread use of single occupancy cars often leads to traffic congestion and its associated ill effects. Using high frequency data from Google Maps, we test whether high-occupancy vehicle (HOV) policies can be an effective tool to combat congestion. Using the unexpected lifting of Jakarta’s HOV policy, we show that after the policy was abandoned delays rose about 39 percent on affected roads during the morning peak—and nearly 69% during the evening peak. Importantly, this was not due to simply a substitution from other roads to the former HOV routes: the lifting of the policy led to worse traffic throughout the city, even on roads that had never been restricted or at times of the day when restrictions had never been in place. The increase in traffic persisted long after the policy was lifted. In short, we find that HOV policies can greatly improve traffic conditions.