A co-worker dropped by my desk the other day and commented on how sparsely populated the MnPass express lanes are on weekends and during off-peak hours on weekdays and holidays. She wondered: Is it ever legal for solo ­drivers to use them?

MnPass lanes on Interstate 394 between Hwy. 100 in Golden ­Valley and I-494 in Minnetonka, and on I-35W between Burnsville and downtown Minneapolis, revert to general traffic lanes outside weekday rush-hour periods. They can be used by any motorist at those times, said Brian Kary, freeway operations engineer for the Minnesota Department of Transportation.

Signs above the high occupancy toll (HOT) lanes marked with a diamond will display the word "open" when general traffic can use them. No fees are charged and vehicles do not have to be carrying more than two people. But still, motorists who opt to drive in the HOT lane are not allowed to cross the double white line that separates it from the general traffic lanes. Drivers must also enter or exit the lanes at designated points along the corridor. Violations come with a fine of up to $142.

The MnPass lanes on I-35W are reserved for carpools, motorcycles and all types of buses from 6 to 10 a.m. and 3 to 7 p.m. on weekdays. Solo motorists can pay to drive in the lanes during those hours. They must have a transponder on the windshield that MnDOT uses to deduct the appropriate fee. The cost to drive in the lanes is ­displayed when fees are charged.

One place on I-35W where motorists should NOT be driving during non-rush hour periods is on the dynamic shoulder that runs from 42nd Street to downtown Minneapolis. That restricted lane is part of the MnPass system and is to be used only during peak periods by carpoolers and toll-paying solo drivers. Except in special circumstances, a red "X" is displayed on signs above the lanes and general traffic is not allowed to use them.

The HOT lanes on I-394 west of Hwy. 100 are restricted to carpools, buses and motorcycles and toll-paying drivers from 6 to 10 a.m. and 2 to 7 p.m. on weekdays. The reversible HOT lanes east of Hwy. 100 to downtown Minneapolis are tolled 24 hours.

For drivers who know their route

While we are on the subject of freeways, Dick Trickel said he appreciates the overhead ­electronic message boards that display travel times, but wonders why they can't add the distance to the travel time calculation. If you are not from the Twin Cities or are in a part of town you are not familiar with, adding the mileage information would be valuable, he said.

Kary said MnDOT considered adding the distance element to the popular signs. But since they already show two or three destinations, adding mileage would be tough because space is limited.

Kary said MnDOT considered putting up two-panel signs that would allow travel times with mileage to change every few seconds. MnDOT declined because the constant switching could become more of a distraction than a help.

"We want to limit what's up there because it becomes a lot to read," Kary said. "It becomes too distracting and people slow down to read it."

Kary said the travel times are geared for commuters who probably know their route. He said MnDOT picks major destinations and matches those with the green guide signs along the freeway to tell motorists how far they have to go.

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