An answer from Denys Vielkanowitz, signal systems management engineer for the city of Wilmington.

The situation could be due to any one of several reasons, said Denys Vielkanowitz, signal systems management engineer for the city of Wilmington.

He said that under certain circumstances, there is a minimum amount of time, or delay, that a vehicle must wait to be recognized by the traffic signal controller.

“For this type of left turn, 15 seconds is typical. This delay is useful in light traffic conditions because the green arrow is not always necessary for someone to make the turning movement. Under heavy traffic conditions, a vehicle will typically meet this delay and the arrow will appear at the next available time,” Vielkanowitz said.

He said the second possibility is that the vehicle detector loop, located in the road behind the stop line, may be malfunctioning.

“Any time you put electronics outside, it is constantly being subjected to Mother Nature and the stress and friction of vehicles that drive over it,” Vielkanowitz said.

A third possibility, he said, is that a vehicle stopped to turn left may have stopped past the stop line.

“Vehicle detector loops are located behind the stop line. Therefore, it is important to remember not to cross the stop line while waiting for a traffic signal,” Vielkanowtiz said.

“We will inspect this location and take the necessary action to repair the issue,” he said.

Date posted: April 21, 2011

User-contributed question by:
Bill Trant