Driverless vehicles will safely wiz through intersections at the full speed limit, according to researchers from Virginia Tech Transportation Research.

Autonomous vehicles will turn themselves over to an automated intersection controller, with the controller tweaking their trajectory to prevent crashes, explained Ismail Zohdy of Cairo, Egypt, a Ph.D. student in civil engineering at Virginia Tech, and Hesham Rakha, director of the Center for Sustainable Mobility at the transportation institute and professor of civil engineering at the university.

Driver behavior is considered to be the leading cause of more than 90 percent of accidents, so safety is the primary motivation for driverless vehicles. A driverless vehicle can much more accurately judge distances and velocities, and react instantly to situations that could cause an accident due to a delayed human reaction, the researchers say.

Proposed intersection traffic-control system

The proposed system considers the vehicles’ location, speed, and acceleration plus the surrounding environment, such as weather and intersection characteristics. An intersection controller would allow vehicles to keep moving, reduces the delay for each vehicle compared to traditional intersection control.

Intelligent transportation systems are an interaction of many complex entities that communicate with each other, such as vehicles, traffic signals, and advisory signs. Driverless vehicles would be capable of interacting with these other entities, according to the researchers.

In Zohdy and Rakha’s research, the intersection controller governs vehicles within 200 meters (218.7 yards) from the intersection. The vehicles report their physical characteristics, such as power, mass, speed, location, and acceleration. “The aim of giving complete authority to the controller is to overcome any selfish behavior by an autonomous vehicle and benefit all vehicles in the intersection zone,” said Zohdy.

“The controller determines the optimum speed and acceleration at each time step for every vehicle within the intersection zone by processing the input data through a real-time simulator/tool.”

The research was done based on a four-way intersection with one vehicle entering from each direction and moving straight through. It has since been expanded and tested on more congested intersections involving not fully deployed systems and comparing this type of control to traffic signal and roundabout control.

Zohdy and Rakha will also be testing their system on a roundabout on the Virginia Tech campus as part of the Connected Vehicle/Infrastructure University Transportation Center.

Their research on Optimizing Driverless Vehicles at Intersections, presented at the Intelligent Transportation Society World Congress in Vienna, won the Best Scientific Paper Award for North America (ITS stands for intelligent transportation systems).

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