A concrete median is all that separates the traffic on I-94 at the east end of the Lowry Hill Tunnel. On Wednesday, it wasn't enough to stop a speeding westbound semitrailer truck from jumping the 32-inch-high barrier and setting off a crash in the eastbound lanes involving at least three vehicles, including one that rolled over.

No one was seriously injured in the crash, which occurred in rainy weather about 5:30 a.m. and tied up traffic for hours.

A similar scene played out in February when a milk tanker struck the same barrier and flipped over. In 2011, a semi carrying car parts overturned, killing the driver.

From 2007 to 2012, MnDOT data show there have been 70 crashes in the immediate area. The latest have renewed discussions on how best to improve safety for the 153,000 motorists who pass through the tunnel each day.

"MnDOT is concerned with this and will determine with the Federal Highway Administration what the best solution or solutions could be to make the area as safe as possible," said West Area Engineer Ron Rauchle. "We don't want this situation to persist any longer than it needs to."

MnDOT crews were actually on the scene the day before the crash, studying ways to improve safety. One possibility is a higher barrier. But that could bring a new set of dangers in the form of reduced sightlines, and there is no guarantee that it would prevent a truck from flipping over it, said West Area Manager John Griffith. Banning all trucks from the tunnel would just shift problems to city streets, he said.

There are other factors, too. Pavement conditions caused by weather and aging, whether a vehicle is top heavy, and how fast motorists are driving also have to be taken into consideration, he said.

MnDOT is planning a major pavement rehabilitation project on I-94 between Nicollet Avenue and I-694 in 2016 or 2017. But because the freeway's near right-angled turn is wedged between the Walker Art Center and two historic churches (Hennepin Avenue United Methodist and St. Mark's Episcopal), there is little room for reconfiguration.

"We would like to do something different there … but those buildings are still there," Griffith said. "We need to be careful on what we are trying to design, and not do something just because two trucks went over it. We need to know what caused it."

Speed was identified as a factor in 20 percent of the crashes. The posted speed limit in the area is 55 miles per hour, but large yellow signs advise motorists to slow to 35, the speed MnDOT says motorists can drive without taking unnecessary risks.

Reducing the speed limit would seem arbitrary, Rauchle said, because many drivers go above it. In Wednesday's crash, driver Cynthia Ockwig was estimated to be traveling 60 mph, according to the State Patrol.

Besides a higher barrier, new pavement surface and markings, and improved lighting and signage — all being considered — the best antidote might be driver education, Rauchle said.

"Are they seeing signs and saying, 'I can handle a faster speed?' " Rauchle said. "How do we raise driver awareness and let them know that there is something ahead that you need to slow down for?"

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