What’s the time in the traffic light line?

KELOLAND.com Original

Traffic signal light at a 26th Street Intersection. KELOLAND News

SIOUX FALLS, S.D. (KELO) — Stop at a traffic light in Sioux Falls and your total wait could be as long as two minutes for the lights to cycle through. Or it could be shorter, as in 60 seconds.

Heath Hoftiezer, the principal traffic engineer for the city of Sioux Falls, said the light cycle is 60 to 150 seconds at the city’s 282 traffic signals.

“The busier a road is, the longer the cycle is,” Hoftiezer said. “Also, the more phases an intersection has, the longer the cycle is.”

Phases include left-turn signals and the like. Hoftiezer said about 60% of the city’s 282 traffic signals have left-turn signals. That’s about 169 traffic signals that may have a longer phase cycle.

There are 86,400 seconds in a 24-hour day. If a traffic signal was at a 60-second cycle for 24 hours, there would be 1,440 60-second cycles throughout the day.

Let’s say a commuter hits those 60-second cycles at three traffic signals on the way to work. That’s 180 seconds or three minutes at traffic signals.

The National Association of City Transportation Officials (NACTO) has said the ideal short cycle for urban roadways is 60 to 90 seconds.

Not all Sioux Falls traffic signal intersections are on a 60-second cycle all day.

Hoftiezer said, “Depending on traffic volumes at an intersection we will have anywhere from one to seven plans that run throughout the day.”

NACTO said that “Cycle lengths may be adjusted according to the time of day to account for fluctuating vehicle or pedestrian volumes. Cycle length adjustments should be minimal and consider both pedestrian and vehicle volumes at peak and off-peak times.”

Traffic count data is used to direct traffic flow to the downtown in the morning and out of the downtown in the afternoon, Hoftiezer said.

According to the Foresite Group’s “Beginner’s Guide to Traffic Signal Timing,” the most common peak periods are in the morning, late afternoon and midday.  These peak periods are typically driven by traffic patterns or daily commutes by direction, the Foresite Group said.

The city has categories of major and minor intersections and the typical wait time is different at each.

The typical delay at major intersections during peak times is 30 to 50 seconds, Hoftiezer said. The wait at a minor intersection is 15 to 30 seconds, he said.

In general, 41st Street would have some major intersections in Sioux Falls. For example, the traffic count between traffic signals at the intersections of 41st Street and Valley View Road and Marion Road was 20,900 on weekdays in 2020.

But traffic counts in 2020 were generally down in Sioux Falls because of the pandemic.

The number was 21,700 in 2019.

The traffic count signal on Amidon Avenue between the intersections of 4th Avenue and Cliff Avenue was 2,500 in 2020.

The wait decreases during non-peak times to 20 to 40 seconds at major intersections and 10 to 15 seconds at minor intersections.

Drivers at a red light have more time to cross through the intersection on a green light than to turn left.

Drivers typically have 35 seconds to pass through on green, Hoftiezer said. The time varies from 20 seconds to 40 seconds.

Drivers typically have 12 seconds to turn left on a green left turn light. The range varies from seven seconds to 25 seconds.

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