Could adding nighttime speed limit signs help decrease traffic deaths?

Reducing speed limits at night

TUCSON, Ariz. (KOLD News 13) - The City of Tucson is working on a plan to lower the number of traffic deaths around the city.

According to TDOT, this year there have been 19 fatalities on the roadways. Nine of them were pedestrians, and five each on motorcycles and in cars. There have been no bicycle fatalities so far in 2019. Compare that to the 69 who were killed on Tucson’s roads in 2018.

An idea proposed by Steve Kozachik during a study session was dropping speed limits at night, across the board, by five miles per hour.

Some of these signs are already in place throughout the city.

According to the City of Tucson, there are several hundred nighttime speed limit signs in Tucson.

There are 30 mph nighttime speed signs on:

  • Greasewood between Ironwood Hill and Speedway Blvd
  • Prince Rd, east of Campbell
  • La Cholla Rd, between Starr Pass and Ajo
  • 22nd St, between I-10 and approx. Euclid
  • Roger Rd, between Fairview and Oracle

There are 35 mph nighttime speed limit signs on:

  • 1st Ave, between Wetmore and Prince
  • Fort Lowell Rd, from Oracle to Country Club Rd
  • Ironwood Hill Drive, west of Silverbell Rd
  • Greasewood, between Speedway and Starr Pass Blvd
  • Valencia Rd, west of I-19
  • Old Spanish Trail, west of Houghton
  • Mary Ann Cleveland, east of Houghton
  • Tanque Verde Rd, west of Catalina Hwy
  • Harrison, north of Irvington

There are 40 mph nighttime speed limit signs on:

  • Mary Ann Cleveland east of the High school
  • Valencia Rd between Alvernon Way and Tucson Blvd.
  • Irvington Rd from Kolb to Houghton
  • Golf Links Rd near Barraza Aviation Pkwy
  • Wilmot Rd north of I-10
  • Silverbell south of Sweetwater

There are 45 mph nighttime speed limit signs on:

  • Valencia Rd west of Houghton
  • Wilmot Rd near Old Vail Connection

So what does the data say? In a study done by ProPublica, a person’s chance of survival goes up when speed goes down, depending on their age.

Chance of Survival:

At 20 MPH

  • 30 Year Old: 97 percent
  • 70 Year Old: 87 percent

At 40 MPH

  • 30-Year-Old: 64 percent
  • 70-Year-Old: 30 percent

At 45 MPH

  • 30-Year-Old: 48 percent
  • 70-Year-Old: 17 percent

Dropping the speed limit from 45 mph and 40 mph lowers the risk by 16 percent for 30 year olds and 13 percent for 70 year olds.

Getting the green light to add more nighttime speed signs is a pretty simple process.

Diahn Swartz, a manager in the Traffic Engineering Division with the City of Tucson said nighttime speed signs do not need to be approved by the mayor and council.

Instead, a list of suggested areas can be submitted to the city clerk's office.

There’s just a few roadblocks to get past first.

"We need to look at the data, for example we need to look at where crashes are happening what kind of crashes are happening, and how they can be prevented.” said Swartz.

To be clear, nothing is in the works just yet. But if the ball were to start rolling, the city, police, and citizens would have to work together.

"Partnering with the police department and also looking at what the data is telling us and identifying candidate corridors based on the data.” explained Swartz.

There is a lot of consideration when deciding what speed limit to set it at. Swartz said they want to aim for safety but be realistic at the same time.

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