Rush hour traffic on Twin Cities metro highways is slowing — and expected to get slower.

Drivers were caught in congestion 25% of the time during the morning and afternoon commutes in 2018, according to the Minnesota Department of Transportation. That’s the highest level of congestion since the state began its annual highway traffic surveys in 1993.

And things are not likely to improve, said Brian Kary, MnDOT’s director of traffic operations. “This is an upward trend that we have been seeing for quite a few years,” he said. “There is only so much we can do. The best we can hope for is that things plateau.”

In the 2018 Metropolitan Freeway Congestion Report, released Monday, MnDOT cited a variety of factors that boosted congestion, which it defines as highway or freeway traffic moving at 45 mph or less. The Twin Cities metro area grew from 3.08 million people in 2017 to 3.11 million in 2018, according to Metropolitan Council figures, and that means more vehicles on the roads. Lower gas prices and a drop in transit ridership also factor into the increased congestion, Kary said.

Motorists are more likely to hit a snarl in the afternoon than in the morning, though drivers on the most traffic-choked routes can plan on riding the brakes part of the way to and from work.

In the mornings between 5 a.m. and 10 a.m., bottlenecks are most likely on Interstate 35W between the cities of Lexington and Arden Hills in the north and from Burnsville up to the Minnesota River in the south. Drivers also are likely to encounter a very slow roll on both directions of Interstate 94 in downtown Minneapolis.

In the evenings, the worst travel spots are on Interstate 494 through Bloomington and Interstate 94 in downtown Minneapolis, where speeds drop below 45 mph for a majority of the peak period from 2 to 7 p.m.

MnDOT collected data from more than 4,000 in-pavement and roadside radar sensors along 782 miles of metro freeways and highways to put the report together. It collected the data in October 2018 and compared it with previous Octobers because that month represents regular traffic patterns with decent weather, school in session, vacation season largely over and road construction projects winding down.

To help alleviate congestion, MnDOT uses ramp meters to control the number of vehicles entering congested roads, displays information about crashes and road conditions on overhead electronic message boards, and has Freeway Incident Response Safety Team trucks respond to crashes and provide traffic control.

MnDOT operates MnPass lanes for carpools, buses, motorcycles and for single drivers who pay to use them. The lanes are designed to move more people efficiently by improving traffic flow in adjacent lanes and allowing for transit services to travel at higher speeds.

When MnDOT completes construction on I-35W in downtown Minneapolis and a new MnPass lane on I-35W from Roseville to Lino Lakes, that may add some short-term improvement, Kary said. But without adding more capacity on highways across the metro, he said, those improvements may just push the problems downstream.

“There is just a lot of stress on the roads,” Kary said. “You will be sharing the roads with more travelers.”

Money for mitigation efforts has been tough to get from the Legislature in recent years.

“As the Twin Cities grow, and our roads continue to age and deteriorate, it’s imperative that we identify a long-term, dedicated funding solution to invest in transportation, improve our system’s efficiency and keep Minnesotans moving,” MnDOT Commissioner Margaret Anderson Kelliher said in a statement.

Commuter Matt Steele of Minneapolis drives on Twin Cities freeways a few times a week and thinks motorists should pay for using the roads.

“Unpredictable trip times can be a frustration, which is why I want to see MnDOT pursue dynamic tolling [congestion pricing] of our urban freeways,” he said. “I’d rather pay a few dollars and ensure I can drive at speed, rather than sit idling in congested traffic.”