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May
23
2019
City improving traffic signal response at intersections
Video detection system in use on 4th Avenue

The City of Yuma has been changing the way its traffic signals receive and process information about the number of vehicles waiting at red lights to improve the efficiency of the signal response.

However, the new equipment – video detection systems that look like cameras – has generated some confusion and discussion among residents. These devices do not store pictures and cannot capture data such as a vehicle’s make and model, or license plate number, etc.

Traffic video detection systems capture and process video signals that indicate one or more vehicles are present at an intersection. These devices detect an object in the roadway – car, truck, motorcycle, pedestrian or bicycle – and send an alert signal to the intersection’s traffic signal controller. The controller then uses this information to determine how long that direction’s light should stay green and which lane movements the signal needs to serve.

Though the City is increasingly using video detection systems, 59 of the City’s 77 intersections equipped with traffic signals still use inductive loops, which motorists can see in roadways. In those systems, a loop wire embedded into the asphalt roadway detects a vehicle by the change in magnetic field that a waiting vehicle resting over the loop causes; that sends a signal to a controller to activate the traffic signal for that lane. In cases where the vehicle moves off the loop, such as a right-turn-on-red situation, the signal for lane activation is canceled.

However, these loop wires can become damaged with construction or disruption to its surrounding pavement. Also, the City also receives occasional complaints that inductive loops may sometimes not recognize a bicycle waiting in the lane for a signal change.

The video detection systems, on the other hand, are less susceptible to damage as they are mounted on traffic signal arms. They can cover a wide detection area – multiple lanes – and it is easy to modify zones from the ground. So in the event of a temporary lane restriction due to construction or work in a manhole or adjacent sidewalk, the City can modify the processor’s detection area.

Traffic video detection systems should not be confused with the nodes the City plans to install atop its streetlights, per its agreements with Siemens and anyCOMM.

The video detection systems will not be part of the anyCOMM system and do not have the same or similar capabilities.

The City plans to continue moving toward the use video detection systems in place of the inductive loops in the future. However, no plan or timetable currently exists for total replacement, so both methods of activating traffic signals will continue to be in use.