Evaluate the Impact of Permanent Emergency Routing Signs on Incident Response and Traffic Diversion

Abstract: Severe traffic incidents and emergency events on interstate highways can lead to significant disruptions, causing delays and compromising safety. Successful detour operations are essential for mitigating these impacts by effectively and efficiently diverting traffic through alternative routes. However, the activation of detour operations is often delayed due to the time and resources required to set up temporary signage, and questions remain about how effectively these signs direct drivers to follow the designated detour routes. To address these challenges, the Virginia Department of Transportation (VDOT) is piloting the use of MUTCD-compliant permanent emergency routing signs along a section of the I-81 corridor, which carries heavy truck traffic and serves as a vital freight route.

While permanent emergency routing signs have been deployed in several states such as New York and Pennsylvania, the effectiveness of these signs in expediting incident response and diverting drivers to the designated detour routes is not well studied in the literature. This study evaluated the impact of these signs on reducing response times and resources expenditures, as well as their effectiveness in directing traffic – especially trucks – to follow designated detour routes during both full lane closures and partial lane closures.

Incidents, traffic volume and speed data were collected before and after sign installation, and statistical analyses were conducted to assess changes in driver behavior and detour efficiency. Traffic data were gathered from continuous count stations on the interstates, temporary traffic sensors, and traffic signal detectors at key locations along the designated detour route. Information on the time and manpower needed to activate detours was collected through interviews with VDOT staff. Regression models were developed to estimate expected traffic volumes under normal conditions, providing a baseline for comparison during detour operations. This study examined how effectively the permanent signs influenced traffic diversion during both mandatory detours (due to full lane closures on the interstate) and voluntary detours during partial lane closures.

Results indicated that the use of permanent emergency routing signs significantly reduced the time and manpower required to activate detours, leading to quicker response times. Interview with DOT staff revealed that such reduction was mainly due to the elimination of the need to set up temporary guide signs. There was a notable increase in driver compliance with designated detour routes, particularly among truck drivers during partial lane closures. By keeping truck traffic on the designated detour route, the impact on local municipal roadway network was significantly reduced.

The research demonstrated the effectiveness of permanent emergency routing signs in directing traffic – especially trucks – along designated detour routes during both full and partial lane closures. It provides valuable insights for Infrastructure Owner Operators (IOOs) in refining incident response strategies and detour operations. This approach holds promise for enhancing the resilience and efficiency of transportation infrastructure and ensuring safer and more reliable travel for the public.