‘Zipper lanes’ price tag is $24M | VailDaily.com

‘Zipper lanes’ price tag is $24M

Jeffrey Leib
The Denver Post
Vail, CO Colorado

DENVER, Colorado – Installing “zipper lanes” on Interstate 70 to reduce eastbound congestion on ski-season Sundays would cost at least $24 million, state transportation officials said Wednesday.

An updated review of the project shows there are no operational hurdles to a plan that, beginning in November 2011, would reverse the traffic flow on one westbound lane to provide three eastbound lanes on a 13-mile stretch of I-70 in the mountains.

The reversed lane would be in operation on winter Sundays from 1 p.m. to about 8 p.m., according to the Colorado Department of Transportation.

Such an effort would likely increase the number of accidents and would boost travel times for westbound drivers, officials said.

And it is still unclear how the state, which faces a budget shortfall next year of up to $1 billion, would pay for it.

In a presentation to the Colorado Transportation Commission on Wednesday, CDOT regional director Tony DeVito said using the reversed lane would cut average eastbound travel times between Georgetown and Evergreen during the busy winter Sunday travel period from 79 minutes to 41 minutes.

However, confining westbound traffic to one lane would double westbound travel times, DeVito said.

The department also is looking at a less costly alternative that would involve hardening the shoulders of I-70 through part of the Clear Creek County corridor for an extra lane for eastbound traffic on winter Sundays. That plan would require a reversed-lane operation for a 5-mile stretch of I-70 so that three lanes of eastbound traffic could be maintained through the Twin Tunnels near Idaho Springs, DeVito said.

Chief engineer Pam Hutton said the department does not yet have a price tag for the hard-shoulder alternative.

CDOT has worked for years on an environmental impact statement for the I-70 mountain corridor that has come up with long-term solutions, including highway widening and construction of a train line through the corridor, that would likely cost well over $10 billion.

Zipper lanes are considered a stopgap.

Colorado legislators passed a law earlier this year directing CDOT to explore the zipper- lane option. CDOT will present lawmakers with results of the department’s study next month.

Adding zipper lanes – so-called because the process of installing the movable barriers to create the reversible lane reminds some of opening a zipper – would likely result in an increase in the number of Sunday ski-season crashes in the I-70 mountain corridor from the current average of 10.2 a year to 12.8 a year, DeVito said.

More accidents are expected, in part, because adding zipper lanes unavoidably narrows lane widths.

Installation of zipper lanes on winter Sundays also would likely cause additional accidents on Floyd Hill as westbound vehicles would back up routinely for at least 2.5 miles initially and as much as 6 miles in the future, if historic traffic-growth patterns continue, CDOT said in its analysis.

Accidents in the reversible- lane portion of the corridor would be especially problematic because it would likely be more difficult to get emergency vehicles to the site.

Tow trucks would be prepositioned to respond to accidents, DeVito said. CDOT has a goal of a 30-minute response time to resolve an accident and restore the zipper-lane operation.

DeVito said CDOT would not deploy the zipper-lane barriers if it were snowing at a rate of more than an inch and hour, or if snow levels reached 6 inches.

He said it takes about 90 minutes to deploy the zipper-lane barriers and a similar amount of time to return the highway to normal two-lane traffic in each direction.

Clear Creek County Commissioner Kevin O’Malley said that due to snow and other factors, it could come to a point where CDOT would be spending too much for congestion relief on a limited number of Sundays.

“We’re looking at a situation where we’re spending a lot of money for a very limited benefit,” he told commissioners.

Approval from the Federal Highway Administration is needed for CDOT to proceed. Douglas Bennett, a senior regional official for that agency, told commissioners Wednesday that his agency is not convinced spending at least $24 million on a zipper-lane pilot project is the best use of CDOT’s money.

CDOT might end up with a cost of $1 million per Sunday installation of the special lanes, he said, especially if the department is not able to deploy it on some days.

“You need to convince us there isn’t a better solution,” Bennett said.

Both he and O’Malley asked whether it might be better to spend such a sum on permanent improvements to the Twin Tunnels – a perennial bottleneck – to get more reliable congestion relief.

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