With opening day less than a month away, Metro Transit is in the final phase of testing on the D-Line, the agency's newest bus rapid transit line.

"We are working to make sure all systems work together," said Katie Roth, Metro Transit's director of arterial bus rapid transit projects.

Those systems include components such as real-time transit information signs, security cameras, emergency telephones, card readers, vending machines, heat lamps and lighting at the 40 stations along the line. The D-Line largely will replace Route 5 and run between Brooklyn Center and the Mall of America starting Dec. 3.

Testing also includes Transit Signal Priority (TSP) technology, which is designed to keep buses running on time and will be in place at more than 50 intersections on Chicago, Fremont and Emerson avenues.

TSP allows computers on buses to communicate with traffic control signals to request longer green lights or shorter red lights. The signal control unit gets a request from the bus, then decides if it can grant it. The request cannot disrupt other traffic movement.

TSP does not allow buses to preempt a signal to change from red to green, such as police cars, fire trucks and ambulances can.

This week, bus operators will practice driving the 60-foot buses that will be used on the 18-mile line, Roth said.

The D-Line will be Metro Transit's fourth bus rapid transit (BRT) line and comes on line about a year after the opening of the Orange Line, which connects downtown Minneapolis to Burnsville. The agency's other BRT lines include the A-Line, connecting Roseville with the 46th Street Transit Station in south Minneapolis, the C-Line, which runs from downtown Minneapolis to the Brooklyn Center Transit Station, and the Red Line, which travels on Cedar Avenue between Apple Valley and the Mall of America.

Rapid buses operate like light-rail trains on wheels, stopping only at stations and platforms about every quarter- to half-mile. Riders pay fares on the platform before boarding and can board or exit buses through the front or back doors.

With fewer stops and less time taken at stations, BRT offers trips up to 25% faster than traditional bus lines, Metro Transit said. That could be a boon to riders who use Route 5, the state's busiest bus route. Prior to the pandemic, Route 5 provided an average of 15,000 rides every weekday and was one of Metro Transit's slowest.

When service begins, the D-Line will run about every 10 to 15 minutes at most hours of the day. Route 5 along Fremont and Emerson avenues in north Minneapolis will be reduced to every 30 to 60 minutes, and the "F" branch along 26th Avenue will be eliminated. In south Minneapolis, Route 5 will end at 56th Street and Chicago Avenue and no longer serve the Mall of America.