December 10, 2023

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How Wrong-Way Highway Driver Detection Systems Work

A red wrong-way sign posted alongside a highway

The red wrong-way sign is the literal first line of defense for every state DOT.
Photo: Artur Widak/NurPhoto (Getty Images)

Wrong-way highway driver detection systems are becoming more commonplace across the country. Unfortunately, the implementation of these safety systems is a response by state departments of transportation to an increase in fatal collisions caused by drivers taking their cars the wrong way. According to the National Transportation Safety Board (NTSB), about 500 people per year were killed in wrong-way crashes between 2015 and 2018. Between 2010 and 2014, 375 people were killed each year in wrong-way collisions.

Systems vary from state to state but counter wrong-way drivers by using the same broad three-step system: detection, verification and response. The detection step is primarily automated and focused on detecting wrong-way drivers as quickly as possible, driving up the highway off-ramp. Arizona uses a thermal camera array. Florida uses a radar system. Connecticut uses a system of 360-degree cameras. Once a driver is detected, flashing red lights are triggered on the roadside wrong-way signs, and an alert is sent to the state DOT’s traffic management center.

A diagram of the Arizona Department of Transportation's wrong-way detection system

A diagram of the Arizona Department of Transportation’s wrong-way detection system
Graphic: ADOT

The next two steps are intended to be done in quick succession. The traffic management center needs to verify the alert isn’t a false alarm through its CCTV camera system. Once the wrong-way alert is verified, the response to the emergency situation immediately begins.

The appropriate law enforcement agencies are dispatched to intercept the wrong-way driver. At the same time, electronic message signs will alert drivers going in the correct direction about the wrong-way driver and instruct them to take the nearest exit off the highway. Highways with ramp meters will also show a permanent red light to drivers until the wrong way driver passes the on-ramp. Ideally, the driver should realize their life-threatening error or be stopped by the police before colliding head-on with traffic.

The NTSB found drunk drivers were most likely to be wrong-way drivers. The agency reported that 60 percent of wrong-way drivers had a blood alcohol concentration equal to or higher than 0.08 grams per deciliter, the legal limit in every state. Obviously the easiest solution should be to stop people from drinking and driving. Though, we should be making an effort to prevent drivers from being seriously injured or killed due to someone else’s reckless misdeed, regardless.