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Frequently Asked Questions

How does a traffic signal know if there’s a car waiting?

When a traffic signal is installed, we also embed a vehicle detector loop under the road to indicate when a vehicle is waiting.. The detector loop is a wire coil that’s connected to the controller equipment. A small electrical signal is present on the wires and when a car drives over the loops it sends a message to the controller and the controller responds. Vehicles should always stop at the white stop bar painted on the road so that the detector loops can be activated to change the signal.

If I back up and drive forward again, will the signal change quicker?

walk signal

No. Detector loops don’t count the number of vehicles waiting and you may actually end up resetting the system and having to wait longer.

If I get out of my car and push the pedestrian button, will the green light come on quicker?

No. If the traffic control signals are functioning properly, the pedestrian push-button does not make the light turn green sooner. However, it can make the green light last longer since it takes a person longer to walk across a street than it takes for a car to drive across a street.

Why does the left-turn green arrow sometimes work, and other times not?

Left-turn green arrows can be programmed to work during specific periods of the day. Sometimes these features are programmed to operate during the morning and afternoon rush hours, when left turn demand is highest.

Left-turning vehicles are detected by detector loops, which are embedded in the pavement at either the stop bar or approximately three car lengths back from the stop bar in the left-turn lane. This helps to keep traffic moving.

I have to wait a long time to turn left because the existing left turn green arrow is too short. Why can’t you make the left turn light last longer?

Developing traffic signal timings is a balancing act where we try to move traffic fairly in all directions. In some cases, it would be great to have a longer left-turn green, but we can’t because of all the traffic arriving at the intersection from other directions.

red traffic light

Why do I sometimes get stopped at every signal, while at other times I can travel through lots of signals without having to stop at a red?

The traffic signals are generally synchronized or coordinated to minimize stops and delays on the major roadways. The effectiveness of traffic signal coordination is influenced by a number of factors including such things as the spacing of the signals along the road, the operating speed of traffic, the vehicle or pedestrian demand on the side street and the traffic signal cycle length.

The goal of signal coordination is to get the greatest number of vehicles through the system with the fewest stops in the most safe and efficient manner. It would be ideal if every vehicle entering the system could proceed through the system without stopping. Unfortunately, this isn’t possible, even in the best-spaced, best-designed systems. Therefore, in traffic coordination, the majority rules, and the busiest traffic movements are given priority over the
smaller traffic movements.


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