In March 2016, Jakarta, Indonesia, with a population of more than 30 million, abruptly ended a high-occupancy vehicle (HOV) policy that required three passengers in a car during peak hours. The sudden halt provided a team from Harvard and MIT with valuable insights into how carpooling affects traffic flow within the megacity.
In a paper published in Science, the team reported that after the policy was abruptly abandoned, delays rose from 2.1 to 3.1 minutes per kilometer (min/km) in the morning peak (a 46% increase) and from 2.8 to 5.3 min/km (an 87% increase) in the evening peak.
The lifting of the policy led to worse traffic throughout the city, even on roads that had never been restricted or at times when restrictions had never been in place. In short, the team found that HOV policies can greatly improve traffic conditions. . . .
