Wyoming DOT Launches Variable Speed Limit Sign Test

The Wyoming Department of Transportation recently launched a pilot program to semi-automate Variable Speed Limit or VSL signs this winter along selected state highways in an effort to increase motorist safety by adjusting speed limits to quickly changing weather conditions.

[Above photo by the Wyoming DOT]

This automated pilot program uses data from Wyoming DOT highway sensors to adjust the speed indicated on the VSL signs when employees may not be in the area to initiate the changes themselves.

Photo by the Wyoming DOT

This results in quicker speed adjustments, which can match how quickly conditions change on Wyoming highways, the agency said.

The program will start with two sections of VSL signs, one located along I-80 between Laramie and Rawlins and another on Wyoming Highway 28 over South Pass. If the program is successful, the agency said it could expand it to other VSLs around the state.

“[VSL] automation still has a human component,” stressed Vince Garcia, Intelligent Transportation Systems program manager at Wyoming DOT, in a statement.

“Speed limit changes prompted by the program can be adjusted or even vetoed by a boots on the ground employee like a trooper or highway maintainer,” he added.

Photo by the Wyoming Highway Patrol

For example, if sensors indicate traffic can resume normal interstate speeds, but there is an active crash investigation and cleanup in the area, troopers can hold the lower speed to protect first responders and keep the traveling public safe, Wyoming DOT said.

Several state departments of transportation are using VSL technology as part of their efforts to improve overall highway safety.

For example, in August 2021, the Idaho Transportation Department deployed VSL technology within an I-84 work zone in Canyon County as a way to enhance safety for its work crews and motorists alike.

In July, the Ohio Department of Transportation deployed VSL signs as part of a broad safety technology test at highway construction sites where I-70, I-71, and State Route 315 meet in downtown Columbus.

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