Q. Why don’t all pedestrian walk signals automatically change when the vehicle signals change, rather than only when a pedestrian pushes a button to request a walk light?

A. “Every intersection is different,” notes city spokesman Robert Kellar. “As you move away from the core of the city, many of our signalized intersections have far less frequent pedestrian use and may have wider crossings due to the number of vehicle lanes. These locations are best served by push-button calls for service.”

Pushing the button provides an input to the system, which is weighed with other inputs to determine signal timing. Ann Arbor’s signals system has been quietly incorporating increasing amounts of sensor information to make it more responsive to traffic, but some intersections continue to use older approaches. “We generally won’t alter an intersection with an older pedestrian system until there are other alterations to be made there, too,” Kellar says.

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