SIOUX FALLS, S.D. - Many drivers have probably sat at a red light in the car, watched the opposite crosswalk timer count down to zero and think their light is about to turn green. Then, all of a sudden the timer starts right back at the top. In this week's Have You Ever Wondered... KSFY News reporter Vanessa Gomez finds out why all of the crosswalk timers aren't synced up to the stoplights in Sioux Falls.
If you've walked in Downtown Sioux Falls, you may have noticed that there aren't any buttons to push for the crosswalk. That's because the majority of them are on self automated timers.
"Pre-timed in the downtown is good. It's a pedestrian friendly system because the pedestrians come up all the time," said Heath Hoftiezer, the principal traffic engineer for the city of Sioux Falls.
Stoplights change to yellow when the pedestrian countdown timer hits zero in Downtown Sioux Falls. Essentially, the timers match to the changing lights. This is called a pre-timed operation in an intersection, which is one of three different types of intersections in Sioux Falls. Another is a semi-actuated operation.
"So what happens on those intersections is for the most part, the countdown timers along a major street like on West 12th Street- most of the timers on 12th Street will count down to zero right when it changes to yellow," said Hoftiezer.
But on a side street like Western Avenue, the light will only stay green for however many cars it detects because these streets aren't as busy.
"If 10 cars come through, the vehicle phase might end up being 20 to 30 seconds," said Hoftiezer. "Maybe that's longer than the pedestrian was. So the light stays on an extra 5 or 6 seconds after the pedestrian phase got done."
The last type of intersection is a fully actuated operation.
"Every single phase of the intersections, we're detecting vehicles. The operation of the intersection is different every single cycle," said Hoftiezer.
So it doesn't depend on the crosswalk timer. The new camera detection on Minnesota Avenue is a good example of this.
"So the idea there is that if traffic gaps out from any approach, it will move to the next approach quicker," said Hoftiezer.
Most detection systems are underground though. So Hoftiezer said to make sure you're pulled all the way up to the stop bar to change the light. Hoftiezer said outside of downtown, it makes sense to have traffic signals run off of car detection because there aren't that many pedestrians.
If you have a question you'd like Vanessa Gomez to answer, send her an email at firstname.lastname@example.org.