Travelers on Interstate 70 will get the chance this week to sound off on proposed toll rates on a soon-to-open express lane for ski traffic — a lane that could rank as the nation’s priciest per mile.

The eastbound-only lane, designed to relieve the crushing congestion of a return trip to the city from Colorado’s mountain ski resorts, is scheduled to open to vehicles in December.

Colorado Department of Transportation staff members have suggested a tolling range of $3 to $30 for the 13-mile stretch, which lies between the Empire exit and Central City Parkway, near Idaho Springs.

At the maximum suggested toll rate, motorists would be paying $2.31 a mile to ride the express lane — a higher rate than any other toll road in the United States.

CDOT spokeswoman Amy Ford said that although the suggested cap for use of the lane is $30, it’s far from certain that price level will ever be reached.

“We may never even touch $30,” she said. “This will be a market-driven process.”

In other words, the amount of traffic on the highway will set the toll — a concept known as “congestion pricing.” The nastier the snarl, the more it will cost to shift into the express lane to escape the gridlock.

Ford said the idea is to have the toll adjust throughout the day so that a speed of 40 mph to 45 mph is maintained in the express lane, which equates to 750 to 900 vehicles per hour.

“The guarantee of this lane is that we will always have one lane with reliable travel speeds,” Ford said.

And unlike traditional toll roads, eastbound I-70 still will provide two general-purpose lanes that will be free for those unwilling to pay a toll.

“It’s about choice,” Ford said.

CDOT’s High Performance Transportation Enterprise Board is expected to vote on exact tolls in the next few weeks. A public meeting on the issue will be Tuesday at the Elks Lodge in Idaho Springs.

Ford described the I-70 mountain corridor as unique in the nation because of its strong connection to recreational traffic. For a family that has just spent thousands of dollars on a ski vacation weekend, she said it may be worth $30 to ensure an on-time arrival at the airport.

High-occupancy vehicles will not be allowed to ride the express lane for free because most of the weekend traffic in the corridor is made up of cars carrying three or more passengers, Ford said.

The I-70 express lane was carved out of the inside shoulder of the highway and, as such, is not considered a proper lane for year-round use. Federal transportation officials will allow the lane to be operational 72 days a year, which most likely will be on weekends and Monday holidays.

The lane should save eastbound travelers 30 minutes during peak travel times, compared with those traveling in the general-purpose lanes, she said. For those in the regular lanes, Ford said CDOT’s hope is that the extra lane will add enough capacity to prevent things from getting worse.

The $72 million project was paid for with a mix of federal and state funds, in addition to a loan taken out by CDOT. Ford said the tolls collected will be used to pay back the $24.6 million loan.

Margaret Bowes, program manager for the I-70 Coalition, said the express lane represents the first major capacity addition to the highway since the Eisenhower-Johnson Memorial Tunnel was completed in the late 1970s.

“It’s just hard reality that with state and federal funding being so limited, we need to be creative,” Bowes said.

She said businesses up and down the corridor have grown increasingly concerned about the negative effects of stop-and-go traffic on I-70. Bowes said the eastbound effort is a good start but “we would love to see it implemented in both directions.”

Clear Creek County Commissioner Tim Mauck said there needs to be a more “holistic” approach to solving the congestion conundrum on I-70 as the state’s population continues to burgeon.

The bigger issue is the Eisenhower Tunnel has been outgrown, “and that problem is a $2 billion fix.” At least the express lane, he said, will “buy us some time for the next 10 years.”

John Aguilar: 303-954-1695, jaguilar@denverpost.com or @abuvthefold