Time gets wasted at traffic signals; report explores how much

March 12, 2021

Tyson Fisher

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How much time are motorists losing at traffic signals? A new study by Inrix has an answer to that question.

Known for its Global Traffic Scorecard, traffic data analysis company Inrix has expanded its congestion data by studying traffic signals with its new U.S. Signals Scorecard. The scorecard analyzed nearly a billion traffic signal interactions accounting for about two-thirds of the nation’s signals to find out how much time is being spent waiting for that light to turn green.

According to the report, nearly 7% of the total time of a random trip in the U.S. was spent waiting at one of more than 200,000 traffic signals studied.

The average trip in the study was about 10 miles lasting 17 minutes. During an average trip, a vehicle passed through about four signals and spent nearly 70 seconds in total delay at those signals. Scaling up to account for all traffic signals in the nation, the time spent waiting at a light is closer to 10% of total trip time.

Midday periods Monday through Saturday saw more demand. Consequently, traffic signals during that timeframe performed more poorly than the typical weekday morning commute. However, the effects on commuter travel caused by the pandemic has likely changes some of these patterns. Inrix estimates it could take months or years to establish a new normal in traffic patterns and adjusting traffic signals accordingly.

At the national level, an average about 17,400 vehicles crossed an average signal. Even accounting for about two-thirds of vehicles getting through on green, each vehicle was delayed 17 seconds for each crossing. Those that did not make the green light waited an average of 45 seconds. That time adds up. In total, the average traffic signal caused nearly 82 total hours of delay each day.

It may not seem like it, but motorists are more likely to arrive at a traffic signal when the light is green.

The weekly weighted average has two-thirds of motorists getting the green light on arrival. From noon through the afternoon peak period, the average green light arrival was just under 60%. The worst time to catch a green light is Friday 3:15 p.m. to 4:15 p.m. with only 56.6% of motorists arriving on green. For the early birds, about 80% of motorists driving at around 4 a.m. on a Tuesday catch a green light.

Traffic signal delay per vehicle by hour
Source: Inrix

Broken down by state, the traffic signal situation varies. Arrival on green ranges from 56% in Nevada to 69% in Nebraska. Nevada also has the highest stops per day per signal at more than 10,000 stops. South Dakota and Iowa tied for the lowest number of stops per day per signal with 4,500 stops. Nevada scored the highest in crossing per day per signal (24,000), total hours of delay per day per signal (144 hours) and average delay per vehicle (21.1 seconds).

There was a large gap between states when accounting for the total statewide daily delay. On the low end, vehicles in Vermont and Wyoming waited 17,000 hours each day. That is less than 1% of the highest statewide daily delay in California at 2.7 million hours per day. However, that is likely due to population size.

Among the 25 biggest cities in the nation, fewer Bostonians caught a green light with a rate of 56%. On the other hand, Denver motorists had a high of 68% arrival-on-green rate. The longest delay per vehicle was in New York City at 22.1 seconds. With an average wait of 14.5 seconds, St. Louis had the lowest delay per vehicle.

Broken down even further, Inrix found the worst urban intersections by traffic signals.

The top 10 worst intersections by delay per vehicle are (county and state):

  1. West Bailey Boswell Road and Saginaw Boulevard in Tarrant, Texas (110-second delay per vehicle).
  2. West Nine Mile Road and N. Palafox Street in Escambia, Fla. (75-second delay).
  3. Sands Avenue and S. Las Vegas Boulevard in Clark, Nev. (73-second delay).
  4. South Walnut Grove Road and Highway 287 in Ellis, Texas (72.5-second delay).
  5. Airport Boulevard and Schillinger Road S. in Mobile, Ala. (69-second delay).
  6. Azle Avenue and Boat Club Road in Tarrant, Texas (68-second delay).
  7. Hialeah Gardens Boulevard and NW 138th Street in Miami-Dade, Fla. (68-second delay).
  8. Lamb Boulevard and East Charleston Boulevard in Clark, Nev. (68-second delay).
  9. Randall Road and Algonquin Road in McHenry, Ill. (65-second delay).
  10. Airport Boulevard and University Boulevard S. in Mobile, Ala. (65-second delay).

The top 10 worst intersections by arrival on green at traffic signals are (county and state):

  1. Gravois Bluffs Boulevard and MO 141 in St. Louis, Mo. (17.8%).
  2. 34th Street and Grays Ferry Avenue in Philadelphia, Pa. (17.8%).
  3. 7 Mile Road and Haggerty Road in Wayne, Mich. (19.2%).
  4. Archer Avenue and S. Pulaski Road in Cook, Ill. (19.8%).
  5. Torrence Avenue and S. Brainard Avenue in Cook, Ill. (19.8%).
  6. Pulaski Road and W. Marquette Road in Cook, Ill. (19.9%).
  7. Manchester Boulevard and S. Western Avenue in Los Angeles, Calif. (20%).
  8. Dupont Parkway in New Castle, Del. (20%).
  9. Spur 63 and W. Marshall Avenue in Gregg, Texas (20%).
  10. Kings Highway Boulevard at Interstate 64 in St. Louis (city), Mo. (20.2%).

Check out the full report here. LL