Han Ximin

ximhan@126.com

A NEW traffic organization method called a continuous flow intersection, also known as the displaced left turn, was introduced at the intersection of Caitian Road and Fuhua Road in Futian District recently to reduce congestion.

A continuous flow intersection is an unconventional intersection that displaces the right turn bay to the opposite side of oncoming traffic, called a “CFI Leg.”

At a traditional intersection, through traffic must wait while left-turning traffic has an “arrow.” Heavy left-turning vehicles at conventional intersections almost always have their own traffic signals. These separate signal phases increase safety but reduce efficiency.

The introduction of the CFI, which removes the conflict between left-turning vehicles and oncoming traffic, allows opposing left-turning vehicles and through traffic to occur simultaneously by using one signal at the main intersection.

For example, while east-west traffic is moving, left-turning vehicles on the north-south street cross over oncoming traffic. Then when the north-south signals turn green, traffic can travel both straight and to the left at the same time, because the left-turning vehicles are already on the opposite side of the oncoming traffic.

The signals at the main intersection and the sub intersection are operated by two-phase fixed-time signal controllers with signals coordinated to provide smooth traffic flow.

Shenzhen is the first city in China to introduce CFI, which has already shown great potential for improving traffic flow at intersections.

A nine-day trial operation at the Caitian-Fuhua intersection has proven that the method is simple for drivers to understand. Most drivers were able to move their vehicles into the left-turn area by following the road signs and directives. Statistics showed the intersection delay was lowered by 24.1 percent and intersection efficiency had been improved by 29 percent.

Police said at a news conference yesterday that CFI will be a standard setup at major intersections with heavy traffic.

Shenzhen has introduced multiple measures in the past years, such as tidal lanes, HOV lanes and reversible lanes, to improve traffic efficiency and reduce congestion. Unlike these methods, which maximize the use of intersection space, CFI uses time differences to optimize traffic flow.