Virginia will put tolls on Interstate 81 to fund a series of upgrades meant to address intermittent hourslong traffic jams that can seemingly strike at random.

WASHINGTON — Virginia will put tolls on Interstate 81 to fund a series of upgrades meant to address intermittent hourslong traffic jams that can seemingly strike at random.

Gov. Ralph Northam and Republican lawmakers representing the I-81 corridor announced their support Tuesday for tolling rather than a regional gas tax that was also considered

The legislative proposal that’s expected to be approved in the short session beginning Wednesday would set limits on toll prices and provide for a discounted annual pass for cars that would allow unlimited use of the highway. The unlimited pass is expected to cost somewhere around $30 depending on final negotiations and other considerations.

Electronic toll gantries are expected to be set every 40 to 60 miles or so along I-81, with regular rates set at up to 11 cents a mile for cars and 17 cents a mile for trucks. That would equate to about $55 for trucks to travel the length of I-81 during daylight hours. Tolls would be discounted overnight to encourage truck drivers and others to travel at less-busy times, but the tolls would be a fixed price, unlike the variable cost of lanes on interstates 66, 95 and 495.

The I-81 tolls are expected to bring in about $150 million per year.

That would pay for an estimated $2.2 billion in projects along I-81 and parallel routes regularly used as detours. The projects include efforts to more quickly clear crashes, add message boards to warn drivers of crashes ahead, and to widen several parts of I-81, including the area where I-66 traffic merges to head south.

I-81 backups are most frequently due to crashes that can take hours to clear, as drivers sit at a standstill due to the long distance between exits.