If you’re traveling down the highway some night, particularly in the Twin Cities area, you may notice brightly lit work zones and road crews in high-visibility clothing filling potholes, repairing guard rails, pouring concrete: you name it.

Doing some road construction and maintenance work at night is one way the Minnesota Department of Transportation is minimizing the impact to the traveling public and increasing motorist safety, according to a press release.

“Crews can sometimes work more efficiently at night when traffic volumes aren’t as high as during the day,” said Michael Beer, MnDOT Metro construction engineer. “Night time also is helpful for contractors to more efficiently get materials and equipment to and from a project in reduced traffic congestion.”

The Interstate 35W at 94th Street and Highway 100 projects in the Twin Cities involve bridge redecking work, which requires new concrete. Pouring concrete during cooler night temperatures prevents it from drying faster than it should and makes for a more durable, longer lasting deck, said Beer.

In Greater Minnesota, a project on I-35 in Owatonna required night work this season so crews could place bridge beams on the newly constructed abutments. In this project, a local road was closed from 9 p.m. through 5 a.m.

Maintenance projects are also sometimes done at night. MnDOT employs several maintenance crews specifically to work night hours.

“Many corridors and routes are so heavily traveled that night time is the only time we can do the work safely,” said Greg Coughlin, MnDOT Metro director of operations and maintenance. “If we’re filling in potholes or repairing guard rails, we might have lane closures that we can’t get by with other than nights or on weekends. At night, we’re also not impacting communities and people’s daily business.”

Crews often get projects done faster at night because of fewer traffic interruptions.

“Our lane closure policy limits windows of time on many corridors to do maintenance work. The 10-hour shifts are efficient since most night crews load up and go from site to site,” said Coughlin.

When a significant duration of night construction work is necessary, MnDOT sends a letter to people who live or work near the construction zone. The letter explains the construction activity, the expected noise levels, the duration of the work, and provides contact information. The letter is mailed, emailed or hand delivered to all residences and businesses within 500 feet of the work zone. Often, a news release or email alert is also issued.

Construction activities generally prohibited between 10 p.m. and 7 a.m. include pile driving, concrete pavement removal, pavement sawing, concrete crushing and jack hammering. There are times, however, when noise-producing operations occur at night due to the need for pavement to be cured or sawed.

Coughlin said a risk of night work is the potential of drivers who are tired, distracted or under the influence.

“With less traffic on the road, drivers’ speeds can be greater,” Coughlin added. “Motorists should be cautious in work zones at night, slow down and be alert for crews working.”