Once or twice a night, motorists heading out of downtown Minneapolis mistakenly turn onto the Interstate 94 or 394 ramps at N. 4th Street and begin driving the wrong way. It happens a bit more frequently on weekends.

Now the Minnesota Department of Transportation is testing a system that detects drivers going the wrong way on ramps that handle traffic coming off the freeways and into downtown. It hopes to learn whether "Wrong Way" signs equipped with flashing lights are effective in grabbing the attention of wayward motorists and getting them to reverse course before tragedy strikes.

So far, so good, said Derek Leuer, a MnDOT traffic engineer working on the pilot that went live about three weeks ago.

"We have caught a few people who have triggered the system," he said. "It seems they get turned around quickly. It is working."

Much more testing is needed, Leuer said.

The wrong-way detection system works like this: When a driver gets on either ramp going the wrong way, the system activates flashing lights on the "Wrong Way" signs. A camera records the infraction and sends a notification to Leuer and other members of the project team.

For now, that's as far as it goes. In the future, that information could be relayed to MnDOT's traffic management center, which in turn could alert the State Patrol. MnDOT could also warn other drivers that a motorist is coming at them by posting messages on electronic overhead signs.

All that, Leuer said, has yet to be decided and MnDOT needs to ensure that the system is reliable. Right now, he said, the primary goal is warning drivers they're "going where you ought not go."

MnDOT chose the busy and sometimes confusing freeway intersection at N. 4th Street to test its system after watching more than a year's worth of video from downtown. Most of the wrong-way offenses appear to take place between 2 and 4 a.m., Leuer said.

Westbound drivers leaving downtown on westbound I-94 or I-394 are supposed to use the ramp at N. 3rd Street, but videos showed many drivers inadvertently turning onto N. 4th Street west of Hennepin and 1st avenues and continuing onto the freeway ramps reserved for inbound traffic.

With no signs or traffic lights facing wayward drivers on N. 4th Street, the system might be the only warning to motorists informing them they are going the wrong way. Drivers on N. 2nd Avenue also were spotted turning onto the inbound ramps.

Leuer said he understands how it can happen.

"It's a pretty tight urban area with lots going on," he said, pointing out that the 94/394/4th Street intersection is near Target Center and Target Field has a large parking garage and lots of wayfinding signs conveying a bevy of information. "It's easy to get confused and turned around. It's been a known issue."

Neither MnDOT nor the State Patrol have reported any crashes on the downtown ramps resulting from wrong-way drivers. But the potential for a crash pops up more often than many people realize.

The State Patrol each year receives about 1,500 calls statewide about drivers going the wrong way, including 1,100 so far this year, said Lt. Gordon Shank of the State Patrol.

Between 2015 and 2019, there were 82 wrecks involving wrong-way drivers on freeways and ramps, leading to 21 deaths, according to the state Department of Public Safety (DPS). When other types of roads are included, such as state highways, county roads and city streets, the crash tally over the same four years jumps to 1,958 and 134 deaths.

The numbers include vehicles that crossed the centerline and struck another vehicle, according to the DPS.

"It's a scary situation" to have a vehicle coming toward you in your lane, Shank said. If there is time to react, he advises drivers to "move right or left to another lane or onto a shoulder because they are not going to move for you." He also said to call 911.

Shank said he welcomes tools like MnDOT's wrong-way detection system.

"Anything we can do to prevent [wrong-way drivers] or get them stopped quicker is good," Shank said. "They are a danger for everybody, including themselves."