Best traffic policies for megacities

Urbanisation has many advantages. By bringing people togetherphysically, cities inspire innovation and fuel opportunity. They bringworkers closer to jobs and facilitate the diffusion of arts and culture.But the benefits of urban life are often accompanied by costs.Perhaps none feels more burdensome – and downright infuriating – thantraffic congestion. Packed roads and bumper-to-bumper traffic mean timewasted and workdays shortened. And stationary vehicles still emit hugequantities of exhaust fumes, damaging the environment and human health.Many governments have tried to develop policies to reduce trafficcongestion by making it more expensive to get behind the wheel. Since2003, London has successfully implemented a congestion charge, whileSingapore wants to use GPS technology to police its owncongestion-pricing strategy.But such policies are harder to implement in poorer countries, wheretechnological capabilities and infrastructure are often lacking. That iswhy developing countries typically seek more basic policies to improvetraffic flows.For example, in India, Delhi’s suffocating air pollution has led thegovernment to experiment with “even-odd” policies: individuals can driveonly on certain days, based on the numbers on their license plates. Butthis approach has had minimal impact. Gabriel Kreindler of theMassachusetts Institute of Technology has shown that while the policyreduced congestion slightly, drivers circumvented the rule by switchingto other vehicles. Vendors also started selling old plates so thatdrivers could change their tags as needed.Sadly, India did not learn from other countries’ experience. Research byLucas Davis of the University of California, Berkeley, had alreadyshown that a similar policy, implemented in Mexico City in 1989, did notreduce air pollution – the intended goal – or significantly easetraffic congestion. As in Delhi, households in Mexico City foundnumerous ways to skirt the rules.With these documented failures in mind, I worked with colleagues tostudy policies that might be more effective. With MIT’s Benjamin Olkenand Kreindler, we examined the impact in Jakarta, Indonesia, of thewidespread policy of high-occupancy vehicle (HOV) restrictions, whichlimit travel based on the number of passengers in a car.Jakarta has some of the worst traffic gridlock in the world. Since theearly 1990s, Jakarta’s government has sought to improve traffic flowswith a rule that private cars driven during rush hours in the city’scentral business district must contain three or more passengers. Justabout everyone despised this “three-in-one” policy, and people oftencomplained that it created further inconvenience, without reducing timespent on the road. Our research sought to quantify the policy’s trueimpact.In defending the view that the policy was onerous and ineffective,drivers often pointed to an informal business of enlisting“professional” passengers. These “jockeys” would wait near the entrypoints of Jakarta’s three-in-one roads, and, for about 15,000 rupiah($1.10), accompany drivers so their vehicle would be in compliance. Lonedrivers in need of two additional passengers could hire a mother andbaby. According to the policy’s opponents, what looked like carpoolingwas an evasion of it.Eventually, the Jakarta government sided with the policy’s naysayers,announcing in March 2016 that the rules would be suspended indefinitely.For researchers, this created a golden opportunity to measure the impactof a policy before its adoption and immediately after its repeal. To dothat, we queried a Google Maps interface every ten minutes, 24 hours aday. With this real-time, crowd-sourced traffic data for each routepreviously under restriction, we were able to ascertain what happened totraffic flows after the policy was suspended.The results were striking. Despite what drivers – and eventually thegovernment – believed, the three-in-one policy was highly effective inreducing congestion. Our data showed that traffic congestion worsenedsignificantly after the policy was rescinded. On Jakarta’s regulatedroads, average speeds fell from 28kph (17.4mph) to 19kph during themorning rush, and from 21kph to 11kph during the evening rush.Moreover, we found increases in traffic at times of day that were notpreviously regulated, and more vehicles appearing on non-regulated roadsin general. Thus, suspending the three-in-one policy produced moretraffic and less carpooling.These findings have implications for traffic-control measures in othercities. For example, our data imply that Jakarta’s HOV restrictions weremore effective than London’s congestion pricing or Delhi’s even-oddpolicy. The findings also suggest that while Jakarta’s “jockeys” were avisible presence, they did not weaken the effect of the policy.As megacities continue to emerge in many developing countries,strategies like Jakarta’s three-in-one approach can help reducegridlock. But they can succeed in delivering benefits only if they arecrafted wisely, enforced effectively, and studied well. People willalways seek to circumvent regulations, but policymakers must considerall the evidence before they decide to take the off-ramp. – ProjectSyndicate* Rema Hanna is Co-Director of the Evidence for Policy Design research programme at Harvard University.