The Minnesota Department of Transportation spent two years adding traffic lanes in both directions on Interstate 94 between Maple Grove and Rogers and putting in a new interchange at Dayton Parkway.

The agency also put in two cameras in the vicinity of Dayton Parkway with both of them focused on westbound traffic. None were installed on the eastbound side. Drive reader Jeff noticed them and wondered what they are for.

"Are the cameras to track traffic or are they license plate readers?" he asked the Drive in an e-mail. "Why are they there? What is their purpose especially since only facing one direction?"

The cameras are not license plate readers, nor are they hooked into the department's network of cameras that allow motorists to check traffic conditions. The cameras are part of the state's weigh-in-motion truck enforcement system, said MnDOT spokeswoman Anne Meyer.

The cameras are one of 17 weigh-in-motion systems around the state, said Sgt. Jesse Grabow of the State Patrol.

The weigh-in-motion system is used by the Minnesota State Patrol's Commercial Vehicle Inspection (CVI) Section to determine if there are any violations with a commercial vehicle, such as a semitrailer truck, box truck or charter bus or limousine transporting passengers.

The weigh-in-motion system takes a photo and weight reading of all vehicles that cross the sensors in the pavement. The photo helps troopers identify a commercial vehicle if the system indicates it may be violating one of Minnesota's weight laws.

The images obtained by the cameras are not transmitted anywhere or monitored by anyone except troopers who are actively working that site, Meyer said.

If the system identifies a possible violation, troopers can stop the vehicle and investigate to determine if the vehicle is compliance with weight regulations, Grabow said.

The technology is widely used across the United States and in many countries throughout the world, and "helps identify potential violations with commercial vehicles, while allowing those in compliance to continue their route without having to be stopped to have their weight checked," Grabow said.

Minnesota also has six sites where commercial vehicles pull off the highway into a station to be weighed. In 2016, there were 1.89 million vehicles weighed at the stations in Erskine, Lakeland, Moorhead, Ramsey, Saginaw and Worthington, according to MnDOT. The state also has sites without scales or buildings where troopers can use portable scales for roadside weighing.

Troopers conduct about 26,000 commercial vehicle inspections annually, according to the 2018 Minnesota Weight Enforcement 10-year Investment Plan. The report outlined a goal to raise the number to 55,000 annually. To reach that goal, the plan calls for three more weigh stations, with one on I- 94 near St. Cloud, one on I-35 south of Minneapolis, and one on I-90 near Rochester.

The plan said the new facilities and upgrades to current stations are needed since truck traffic is forecast to increase 10 to 11% over the next decade.