Slower speeds, longer trip times, and lots more company on the roads. That’s the future of Twin Cities traffic.

Congestion on metro area highways and freeways jumped by 2 percentage points in 2015 over the previous year, and traffic on the metro’s busiest corridors is only expected to worsen in the coming years as the population grows and increased demand pushes the system closer to capacity, the Minnesota Department of Transportation concludes in a new report. (To view the complete 2015 Metropolitan Freeway System Congestion Report, click here.)

The forecast for more gridlock won’t bring the Twin Cities anywhere close to the snarls endured by drivers in traffic-riddled Los Angeles, Washington, D.C., and New York. But it does mean we will be creeping, rather than cruising, along more often.

“Congestion in metropolitan areas is often inescapable,” said Brian Kary, MnDOT Freeway Operations Engineer. “We try to strike a reasonable balance between existing road capacity and the demand for roads by managing traffic particularly at peak-travel times.”

MnDOT defines congestion as when traffic moves at 45 miles per hour or slower. Its Metropolitan Freeway System Congestion analysis found highways and freeways were clogged 23.4 percent of the time during morning and afternoon rush hours. That was up from 21.4 percent in 2014.

Using field observations and data collected from 3,500 ­sensors embedded in the pavement, MnDOT measured congestion levels on 758 miles of Twin Cities freeways and found that traffic flowed at speeds less than or equal to 45 miles per hour nearly a quarter of the time during the morning and afternoon rush hours. The readings were taken in October 2015, a month when traffic conditions are most typical.

Motorists were most likely to get stuck in traffic on Interstate 94 in the vicinity of I-35W in downtown Minneapolis, eastbound Crosstown (Hwy. 62) between Hwy. 169 and Hwy. 100, both directions of Hwy. 169 approaching I-394, and on I-694 between 35E and 35W through Shoreview. Those routes saw congestion, as defined by MnDOT, five or more hours a day.

By 2028, MnDOT suggests that highways and freeways may be congested close to 30 percent of the time during the hours of 5 and 10 a.m. and 2 and 7 p.m.

While moving at 45 miles per hour or slower may not seem painful, “from driver perspective, anything below 45 for long periods of time and long lengths of time and distance becomes stressful,” said David Schrank, a researcher with the Texas A&M Transportation Institute.

With transportation funding already stretched, MnDOT can’t continue adding lane capacity, so MnDOT’s efforts have turned to congestion management, Kary said. That includes expansion of the MnPass lanes, effective use of ramp meters to space out traffic and encouraging use of mass transit to move more people rather than more vehicles.

“It’s not just about adding concrete,” Schrank said. “Props to MnDOT for what they are doing. They are doing a masterful job at managing the transportation system.”

A bid to increase transportation funding imploded in the final minutes of the legislative session that ended in May, and efforts to reach a deal that could be passed in a special session have not borne fruit.

The new MnDOT report points out the need to beef up public transportation, said Met Council Chair Adam Duininck.

“It’s no surprise to see congestion on our highways is increasing,” he said. “We know our region is growing. By 2040, we’re expecting an additional 750,000 people to live in the region. It’s not practical to build more highways — without an expansion of our regional transit system, our roadways will only continue to get more congested.”

Tim Harlow • 612-673-7768