Wrong-way driver detection

Wrong-way driver detection uses sensors on freeway off-ramps to detect vehicles driving in the wrong direction. The system alerts the driver of their mistake, warns nearby travelers, informs agency staff at a central traffic management center of the need to monitor the situation, and notifies law enforcement so that they can prevent a collision.

Key characteristics




Other names

  • wrong way incident detection
  • wrong way detection

Strategy description

Wrong-way driver detection alerts drivers that they are entering the freeway in the wrong direction, so that they can self-correct before causing a collision. If they do not self-correct, then the system can notify nearby travelers, a central traffic management center, and law enforcement.

All freeway ramps must, at a minimum, include basic “Do Not Enter” and “Wrong Way” signage. Additional low-cost wrong-way driver detection treatments include lowering the mounting height of signs, coloring signposts red to make them stand out, and painting large “wrong-way arrows” on the exit ramp pavement.

More advanced wrong-way driver detection systems apply the following components:

  1. It detects vehicles on the ramp using technologies like radar or video cameras
  2. When the system detects a vehicle entering an off-ramp the wrong way, it communicates to nearby devices. For example, it could flash additional warning indicators, like red flashing lights in the pavement or around a Wrong Way sign. After detecting a wrong-way driver, the system might also trigger a special variable message sign, causing the sign to light up with a “wrong way” message.
  3. If the driver does not self-correct, the system will broadcast wrong way driver information
    • Informing other travelers of the wrong way driver using nearby variable message signs
    • Informing agency staff at a centralized traffic management center so they can track the wrong way driver via video cameras along the corridor
    • Alerting law enforcement officers in the area so they can intercept the wrong way driver before a collision occurs

When to use this strategy

One challenge to installing wrong-way driver detection is determining where drivers are accessing the freeway heading the wrong way. Crash reports indicate where the collision occurred, but are unlikely to indicate where the driver entered the freeway. If a full understanding of where drivers access the freeway is not known, safety experts recommend a systematic approach to installing a wrong-way notification system.

To help prioritize which locations require wrong-way driving detection along a corridor or primary route, agencies can also evaluate road junctions and how intersection visibility and geometrics can affect wrong-way driving. A location with confusing geometry and/or low intersection visibility may be a good candidate for wrong-way driver detection.

Wrong-way driving is relatively rare, and wrong-way driver collisions are even less frequent, but when these incidents occur on high-speed, divided highways, the results can be severe. For example, wrong-way driver collisions accounted for 38 percent of fatalities on Interstate 90 in Washington (1). Nationally, more than 300 people die each year in wrong-way driving collisions (2).

Strategy benefits:

A detection and notification system can help prevent collisions, enhancing safety as well as supporting incident response and management. Recent reports from across the United States show that it can reduce wrong-way collisions by over 40 percent.

  • In San Antonio, the number of wrong-way driver reports fell from 269 to 162 in the five years since the wrong-way driving notification system was installed.
  • In both Rhode Island and on Florida’s turnpike system, 99 percent of detected wrong-way drivers self-corrected after the wrong-way driving notification system was installed (3).

What you need in order to implement

Policy needs:

  • Wrong-way driver detection systems should follow current agency policies related to each element: signing, pavement marking, detection, variable message sign messages, and incident communication protocols. Agencies should coordinate with other stakeholders on these policies.

Planning needs:

  • Implementing wrong-way driver detection requires planning, design, and construction. Due to its cost, it will likely be part of an agency’s normal planning process that includes public involvement, environmental impact analysis, and funding discussions.

Coordination needs:

  • Agencies should coordinate with the centralized traffic management center and law enforcement to determine the number of collisions related to wrong-way movements and other wrong-way incidents (even if a collision did not occur). Agencies should share the value of this information for analysis purposes.
  • Agencies, law enforcement, incident management responders, and the traffic management center should co-develop policies related to wrong-way detection and response.

Equipment needs:

  • Detection equipment (loops, video, radar), signing, communications. Detection equipment can also include loop detectors, video cameras, or radar.
  • Communications from the detectors to the signs, either wired or wireless.
  • Sign installation equipment that includes power supply (typically a hard line to an existing electrical pole or solar power installation).

Maintenance needs:

  • Requires regular maintenance and testing to ensure the system is working properly. To succeed, it also requires regular maintenance of signage and pavement markings.

Agency resources needs:

  • Traffic engineers to place signs and establish proper messaging on variable message signs.

Learn more about this strategy

Federal Highway Administration (FHWA), Wrong Way Driving Road Safety Audit Prompt List, FHWA-SA-13-032, Washington, DC. 2013. 

Illinois Center for Transportation, Guidelines for Reducing Wrong-Way Crashes on Freeways, ICT-R27-90, Urbana, IL. 2014. 

Highway Special Investigation Report: Wrong-Way Driving. National Transportation Safety Board. NTSB/SIR-12/01. PB2012-917003. Adopted Dec 11, 2012 (PDF). 

Works cited:

(1) Washington State Department of Transportation, Final Report: I-90 Operations Study, Olympia, WA, May 2018.

(2) FHWA Office of Safety, Wrong-Way Driving website

(3) Technology Is Turning Wrong-Way Drivers Around. Jen Fifield. Dec 19, 2017. 

(4) Washington State Department of Transportation, Final Report: I-90 Operations Study, Olympia, WA, May 2018.

About key characteristics

Location notes:

Wrong-way driver detection is most useful at freeway off ramps in urban, suburban, and rural areas.

Cost notes:

In order to receive the full benefit of wrong-way driver detection, the cost to install at all ramp locations is significant. For example, a recent report recommending wrong-way driver detection at 16 off-ramps on I-90 in Eastern Washington was estimated at an initial capital cost of $6.2M, and $10,000 to $25,000 in annual operations and maintenance costs (4).

Technology notes:

A basic wrong-way driver system includes detection (often using video or radar) and flashing red lights. A more advanced system communicates wrong-way driver activity to agency staff and law enforcement.

Collaboration notes:

Collaboration among agencies, central traffic management center, and law enforcement is required due to the real-time communication required for a fast response.