A pair of overhead signs emblazoned with the words “Exit Only” in black letters on a yellow background warn drivers on westbound Interstate 94 near the Lowry Hill Tunnel in downtown Minneapolis that the right lane ends a mile ahead and is reserved exclusively for motorists who plan to get off the freeway at I-394.

But Drive reader Joyce Johannson discovered that motorists heading west on the Crosstown in the right lane at Penn Avenue get no such notice. The right lane abruptly ends, and drivers are forced to take the exit ramp to Penn or make a sudden and dangerous maneuver to the left to jump back into traffic.

“It’s an exit only lane, but there is no sign that tells you that,” she wrote in an e-mail to the Drive. “If you’re not familiar with the area, you get caught, and when traffic is heavy, it can be hard to merge left at the last minute.”

She wanted to know why there isn’t a sign designating the far right lane on the westbound Crosstown at Penn Avenue as “Exit Only.” And she wondered how the Minnesota Department of Transportation (MnDOT) decides when to put up such signs.

The Drive took Joyce’s concern and question to MnDOT metro sign engineer Eric Peterson.

Under an old practice from decades ago, MnDOT put up “Exit Only” signs only when auxiliary lanes were a half-mile long or greater. An auxiliary lane is an extra lane between interchanges that gives drivers more time to merge onto the highway or get off. Since the auxiliary lane on the Crosstown between I-35W and the Penn Avenue interchange is less than a half-mile, the lane did not qualify for signage, Peterson said.

Over the years, however, MnDOT studied auxiliary lanes, looking at what other states did and gathering feedback from the public. That resulted in MnDOT removing the half-mile distance threshold as a requirement for “Exit Only” signage, Peterson said.

“MnDOT recognized the benefits of adding ‘Exit Only’ signage for these shorter auxiliary lanes as well,” he said.

With the change in policy, many of the shorter auxiliary lanes across the Twin Cities, such as the one on westbound Crosstown near Penn, now qualify for “Exit Only” signage provided that traffic engineering standards and other criteria are met, Peterson said.

MnDOT has been updating signs in recent years as it carries out construction projects, he said. But the agency still hasn’t gotten to some places on the highway system, including the lane that our Drive reader pointed out.

“Look for it and others on the highway to be updated in future construction,” he said.

Short of an “Exit Only” sign, a series of small dotted lines — rather than full-length lane stripes — painted on the pavement tell drivers that a lane is ending.

In memory of MnDOT workers

The segment of Interstate 94 between Alexandria and Sauk Centre, Minn., is now known as the Kenneth E. Sellon and Eugene B. Schlotfeldt Memorial Highway. Legislators approved the name change in memory of two MnDOT workers who were killed Nov. 14, 1968, while on the job.

Family members of the fallen workers raised money to purchase two memorial signs, which went up in late January.

With them, MnDOT reminds drivers to slow down and watch for signs, equipment and workers when driving through work zones.

Follow news about traffic and commuting at The Drive on startribune.com. Got traffic or transportation questions, or story ideas? E-mail drive@startribune.com, tweet @stribdrive or call Tim Harlow at 612-673-7768.