Drivers who venture onto Interstate 70 in the mountains in two-wheel-drive cars with standard tires during colder months — even on sunny days — are expected to be put on notice soon: That won’t fly anymore.

Such vehicles will need specialized tires or will have to carry traction devices, no matter the weather, between Sept. 1 and May 31 under a bipartisan bill that is heading to Gov. Jared Polis. The legislation, once signed, will beef up the state’s traction law, which currently kicks in before and during winter storms — sometimes catching travelers off guard.

Boulder skier Jeffrey Robinson, 35, had one word for the I-70 drive during this year’s drumbeat of storms: “hellacious.”

He recalled the recurring sight of vehicles with worn-out tires struggling to get moving on the slick interstate after traffic had come to a halt. Many appeared to be rental cars, and some had all-wheel-drive. “They fit the traction law that’s in effect,” said Robinson, a financial adviser whose Audi sedan has snow tires, “but they’re on either all-season tires or just don’t have good traction.”

Four-wheel-drive and all-wheel-drive vehicles already pass muster under the current law if they have sufficient tread, but the bill would set a higher standard. It would increase the minimum tread depth from an eighth of an inch to three-sixteenths of an inch. Little would change for semi-trailers, whose drivers already are required to carry chains at all times during colder months.

But amid talk of the stricter law and the potential for more proactive enforcement by the Colorado State Patrol, the bulk of the concern has focused on two-wheel-drive vehicles.

Their drivers often are under-prepared, state officials say, and they repeatedly are involved in slideoffs, crashes and other traffic-blocking incidents along the busy corridor.

“Ideally we will see fewer closures and less damage to cars involved in accidents,” said state Sen. Kerry Donovan, D-Vail, who is among the bill’s prime sponsors. “We’ll educate the public that if you are going to travel along this section of interstate, you must be prepared.”

From the start of the snowier-than-normal ski season through March, the Colorado Department of Transportation recorded 426 crashes involving passenger vehicles. Another 156 vehicles were involved in slideoffs or spinouts or had mechanical issues, CDOT data shows. Both figures were on pace to exceed the previous two seasons.

“If this new bill prepares all drivers to be adequately equipped when on I-70, we could see fewer closures, which would be a big win for fellow motorists and our maintenance team,” said CDOT spokeswoman Tracy Trulove. “It would keep our team on the road plowing, as opposed to working incidents where motorists are involved.”

Heavy use of traction law

CDOT’s records show that it activated the current traction law for passenger vehicles 164 times between October and March, making for the most frequent use of the law since 2016.

Lawmakers looked to California and some of Colorado’s neighboring states, which in some cases have stricter requirements on mountain passes, as a guide in beefing up the traction law. House Bill 1207 won House approval 46-18 last month, and the Senate approved it 27-6 on April 8.

Under the bill, the existing traction requirements, along with the stricter minimum tread depth for four-wheel-drive vehicles’ tires, would apply to any road where the law is activated during a storm.

But the I-70 corridor — from Dotsero to Morrison — is the only one that would have the traction law automatically active for nine months each year. It has gotten busier than ever the last two seasons, and its interstate width makes it easy for drivers to forget they’re traversing challenging high-altitude terrain.

“Traveling over Vail Pass and through the Eisenhower and Johnson tunnels takes you over the Gore Range and under the Continental Divide — both of those geographic features bring with them extreme conditions, and we want travelers to be prepared,” Donovan said.

But making sure the traction law has teeth will continue to be a vexing issue.

Drivers now are cited with a violation after a crash or spinout if they block traffic. Bills similar to HB-1207 have floundered in the past, but it won more support this year, including from skeptics such as Sen. Ray Scott, R-Grand Junction. He pushed successfully for an amendment that requires CDOT and the Colorado State Patrol in coming months to propose ways to step up enforcement before wrecks occur, either through new rules or legislation.

Among the potential options are routine checkpoints to check equipment and tread depth.

CDOT and the state patrol already have been proactive in other ways.

To clear crashes or allow snow plows to do their work, they pulled the trigger on 180 safety closures from October to March, varying in length from minutes to hours, along the I-70 mountain corridor. That outstripped 121 safety closures during the ski season last year and 159 in 2016-2017, when CDOT began using those closures routinely.

The front fender of a semi-truck ...
Helen H. Richardson, The Denver Post
The front fender of a semi truck lays along westbound Interstate 70 after a multicar pileup near mile marker 208 on March 3, 2019, in Silverthorne.

Rental cars among challenges

Colorado long has faced challenges in getting out-of-state travelers and visitors driving rental cars to comply with the traction law, and that challenge likely will continue, legislators say.

For weekend warriors with two-wheel-drive cars, though, the law is lax in one area: Besides buying a separate set of snow tires for the winter, they also can use all-season tires with a mud/snow designation (often marked on the sidewall with “M+S”). The tire industry acknowledges that they are much less grippy on ice and in slush than proper snow tires, which are made of a rubber compound that’s softer — and grabbier — in subfreezing conditions.

The other option is to buy a set of chains or an “AutoSock” set, which includes traction wraps for tires, to keep handy in the trunk.

Robinson, the Boulder skier, saw a big difference when he put snow tires on his Audi.

“It’s like driving a Sno-Cat,” he said. “It’s actually quite remarkable how good snow tires are.”

Though some lawmakers cited varying concerns in voting against the changes — including the stricter tread depth — Colorado’s trucking industry supported it.

“We have the toughest chain law and penalties within the country for trucks, and we’ve supported that,” Greg Fulton, president of the Colorado Motor Carriers Association, said in an interview. “What’s challenging for us is that … we’re affected by how the rest of the traffic is operating out there.”

He added: “These (crashes) have more of a ripple effect than in the past, when you have that much more traffic.”

Sen. Bob Rankin, a Carbondale Republican who also was a prime sponsor of the bill, called it “one more step toward solving a very difficult and troublesome set of problems” on I-70 during a committee hearing this month.

“This bill will be much appreciated by those of us who travel I-70 a lot,” he said, “but also by the folks who live along that corridor and depend on it.”