How does MDOT determine when traffic lights go into flash mode?

How does MDOT determine when traffic lights go into flash mode?

Traffic lights are an essential part of travel that add both safety and efficiency to every road trip. While many of us are enjoying some much-deserved sleep, the usual red-yellow-green signal pattern also takes a break.

Those who commute during the late night and early morning hours are likely familiar with the flash mode that replaces the typical traffic light. The timetable signals on state-run roads in the Upper Peninsula follow when a flash mode is set up by the Michigan Department of Transportation through ongoing traffic pattern analyses.

“Basically, there’s black hoses out on the street and we’re counting the cars,” MDOT Upper Peninsula traffic and safety engineer Steve Cadeau said. “We’re looking for that time period when traffic goes to less than 50% of its normal operation, and that’s when we’ll consider going into a flash mode. Typically, we’ll extend the normal operation an hour into the slower times, just for an extra added measure of safety.”

The most common range of start times for a flash mode is between 10 :00 p.m. and midnight. The choice of which road gets the red light is based on the volume of traffic.

“The major street is the one with the higher traffic volumes,” Cadeau added. “In a lot of cases it is (a) state trunkline. If it does happen in a situation where, let’s just say, for example, here at Lincoln and Ludington, if Ludington Street ends up having more traffic volume, we would assign that as the major street. We give them the caution yellow at night and most of the green time during the day.”

The traffic lights at the intersection of Lincoln Road and Ludington Street in downtown Escanaba never go into flash mode, and that’s somewhat rare in the Upper Peninsula. These types of intersections maintain a high enough rate of traffic to warrant 24-hour operation.

Currently, many of the computers controlling intersections in the U.P. operate independently, without central communication to MDOT.