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July 29, 2021

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Stop-and-go expert keeps traffic flowing

EDITOR’S note:

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To pedestrians, riders and drivers, traffic lights are just stop-and-go signals, but to Jiang Yunkan, they’re like plugs in a large water tank that control the flow of water.

Jiang, 41, is a senior engineer with the road administration and facility squad of the traffic police in Shanghai’s Pudong New Area.

The main job of him and his colleagues is to ease traffic congestion by adjusting traffic lights according to road conditions.

Jiang’s trade is highly technical, but he would say it’s more of an art in balancing needs.

“We seek solutions that might not serve the maximum needs of everyone on the road but that facilitate smooth traveling for all,” he said.

In 2020, traffic in Pudong was twice as busy as 10 years ago. Over the past decade, the congested parts of the area expanded from its downtown area in the north to the south where a large number of people relocated from other parts of the city. But the road space didn’t grow at the same pace.

Cars, bikes and pedestrians go in all directions at larger intersections in Shanghai, making traffic lights instrumental in relieving congestion.

“Let’s say it takes 15 minutes to drive from point A to point B via an expressway, and it takes 25 minutes to cover the same distance via streets with intersections,” Jiang said. “The 10 minutes lost otherwise might to a large extent be the result of inefficient traffic light schemes.”

The solution is to provide more green lights to travelers and thus reduce the waiting time for them before red lights.

In recent years, traffic lights that can automatically adjust according to road conditions have replaced those that are preset, based on an intelligent and adaptive traffic control system from Australia, known as SCATS. Jiang and his colleagues replaced the electric cables of the SCATS system with optical cables to enable the expansion of its communication network.

The schemes, tailor-made for each intersection, are planned and programmed by Jiang and his colleagues and triggered on real-time traffic data generated by sensors and traffic cameras, and in the latest cases radar, on the streets.

Together with the data, over 2,000, or two in three, intersections with traffic lights in Pudong under the system have been integrated into an intelligent traffic monitoring and analysis platform, thanks to which over 20 major thoroughfares in the new area, including Zhangyang, Jinxiu and Gaoke roads, are configured as “green corridors.”

“Not only was the efficiency of passage for cars increased by 20 percent, but it also contributed to the reduction of carbon emission from cars,” Jiang said. Cars that aren’t moving tend to produce more emissions than those moving relatively fast.

Their work didn’t stop there. Streets of smooth traffic tend to draw more traffic and thus become congested again. In this case, the traffic light schemes have to be adjusted again and, where necessary, traffic lanes reassigned to traffic in different directions.

Jiang works from 7:30am to 6:30pm. During morning and evening rush hours, he usually stays in the monitoring room to observe traffic flow through the busiest parts of the new area to spot problems that need to be addressed. But his job constantly sends him out on foot, too.

“We simulate the traffic flow on the computer, but no computer model can perfectly take into account all minute details and needs on the ground,” Jiang said. “Nor can we get an idea just by looking at the cameras from the monitoring room, because cameras after all have blind spots.”

Bikers, bus stations and the vicinity of smaller streets near major ones could all potentially affect traffic flow, and the needs of pedestrians and people using non-motor vehicles have to be taken into account. In this case, computer models need to be tweaked.

“The role of the traffic police officers at intersections also can’t be ignored, because they often improvise solutions when congestion happens, and that should also be reflected in designing the schemes of the traffic lights,” Jiang said.

For example, sometimes at an intersection, when the straight lane with a green light is clear, a traffic police officer will allow cars waiting on the left-turning lane to go even when their red light is on. Jiang has incorporated this human flexible element into his computer control system.

After 13 years on the job, Jiang says it’s exciting to serve his fellow residents by solving their problems, but he thinks road travel in the city will be made more pleasant if motorists can develop good driving habits.

“Electronic devices distract people a lot nowadays when they drive,” he said. “If you concentrate on driving, you might save a few seconds for others and others will do the same for you.”




 

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