After seven bridges across the state were hit by truckers in the past month, the Minnesota Department of Transportation is cautioning truck drivers to take extra care.

MnDOT is using social media and e-mail to alert truckers that all bridges in the state are generally 14-feet, 6-inches high — those that are lower have signs warning drivers.

"We figured social media and e-mail would be an effective way to alert commercial drivers to things they know but may not be thinking about," said Kevin Gutknecht, MnDOT spokesman. "With a little care and caution, they can keep their vehicles whole and the infrastructure damage free."

In the past month, five bridges have been hit by trucks in the Twin Cities, including a Sept. 8 incident in Minneapolis where a container truck traveling west on Lake Street struck the northbound I-35W bridge. A 44-year-old Mounds View man who was driving the truck was arrested for driving while intoxicated, according to a Minneapolis Police Department report.

The accident caused $335,000 worth of damage to the bridge, which was paid by the trucking carrier's insurance company, Gutknecht said. The I-35W bus stop at Lake Street is still closed, however.

Another two bridges in Minnesota were hit, including a Sept. 8 accident where a semi truck severely damaged a pedestrian bridge on Highway 14 in Winona. The 51-year-old bridge near St. Mary's University was removed a day later and, on Thursday, MnDOT installed a temporary pedestrian bridge in its place.

MnDOT said it plans to construct a permanent pedestrian bridge on the site in the next two to three years "if funding can be obtained."

The causes of bridge accidents vary.

Some truckers are driving on unapproved routes, their cargo may be too tall or their loads may not be secured properly, causing the vehicle to shift or bounce. Other incidents are caused by "human or equipment failure," MnDOT said.

John Hausladen, president of the Minnesota Trucking Association, said the Roseville-based organization was aware of MnDOT's alert and worked with the state agency to advise truckers.

The number of bridge collisions in the past month "does raise concerns, but it's not like it's the same problem repeating over and over," he said. "It's been a flurry of hits in different locations over a short period of time."

Typically, commercial trucks and agricultural equipment are the types of vehicles that hit bridges, MnDOT said. MnDOT doesn't track bridge collisions, but will begin doing so in 2016.

Truck drivers with questions about lane closures and other restrictions are encouraged to access MnDOT's 511mn.org page for more information.

Janet Moore • 612-673-7752