AASHTO Journal - Idaho Adding More ‘Safety Signage’ to State Highway 55

The Idaho Transportation Department (ITD) plans to increase safety signage this spring on seven miles of State Highway 55/Eagle Road, from I-84 to State Highway 44; part of a safety corridor pilot project aimed at reducing crashes by enhancing driver awareness as they travel through 18 signalized intersections on Idaho’s busiest non-interstate highway.

[Above photo by ITD]

The agency explained in a statement that, in 2023, it initially partnered with the Idaho State Police and local cities to form the State Highway-55 Safety Task Force to consider a range of safety enhancement options for the roadway; teaming up with Meridian city staff and the Meridian Police Department as part of that process.

Based on that task force’s findings, the agency will install variable speed limit signs and driver speed feedback signs on SH-55/Eagle Road, to provide better information to motorists regarding traffic conditions.

Other state departments of transportation are engaged in similar efforts.

In December 2024, the Nebraska Department of Transportation began testing Variable Advisory Speed or VAS signs along I-80 from the Wyoming State line east to Exit 95. VAS signs are new safety devices that the agency said would help motorists adjust their behavior for rapidly changing roadway conditions, such as adverse weather, reduced visibility or traffic congestion.

By implementing VAS signs, Nebraska DOT noted that it aims to inform drivers to adapt their speeds proactively, reducing the likelihood of high-speed crashes and their associated risks, such as fatalities, serious injuries and traffic congestion.

The agency added that that, according to Federal Highway Administration data, VAS signs can reduce fatal and injury crashes by up to 51 percent and also help lessen the chances of secondary crashes by preparing motorists for slower traffic ahead.

Additionally, a report issued by the Ohio Department of Transportation in February 2024 found that the use of Variable Speed Limits or VSLs along a section of I-90 in Lake County reduced crashes by 35 percent over a seven-year period.

The Ohio DOT and Lake County Sheriff’s Department worked together to develop the state’s first VSL section of highway on I-90 in 2017; using digital speed limit signs to reduce the speed limit during adverse weather.

The agency noted in a statement that the Ohio General Assembly also played a key role; modifying the state’s speed limit law to give Ohio DOT the authority to temporarily reduce the statutory speed limit along this specific stretch of I-90.

From 2005 to 2015, the agency said I-90 between State Route or SR 44 and SR 528 suffered a yearly average of 76 reported crashes, with 37 occurring in the winter. Since the implementation of the VSL in 2017, crashes along that stretch of I-90 dropped by over 35 percent to an average of 49 per year, with 21 occurring in the winter.

Additionally, since the VSL system went live in 2017, crashes have been reduced by more than half, rear-end crashes dropped from 19 to eight, and fatal and injury crashes decreased from 20 to nine crashes per year, the agency said.