GETTING THERE: I-25 problems at Rockrimmon exit persist

Despite the new higher speed limit on Interstate 25 through Colorado Springs, it isn't all clear sailing for motorists.

The contractor that rebuilt and widened the interstate two years ago, a $150 million project called COSMIX, is working to correct a thorny problem near the Rockrimmon/North Nevada exit.

Northbound interstate traffic in that area has been constricted from three lanes to two and the speed limit has been lowered from 65 mph to 45 mph, causing delays at rush hour and panic braking by motorists not paying attention.

The problem? The roadway, particularly the right shoulder and right lane, has settled, creating an unacceptable dip in the road just before it meets a bridge that takes traffic over Mark Dabling Boulevard.

The problem first surfaced just weeks after COSMIX was completed in July 2007.

At the time, engineers believed the dip occurred when earth near the end of the bridge settled during construction. Sections of the interstate and the new bridges they connect to were completed at different times to avoid disruptions to motorists, and that may have contributed to the problem.

Engineers also suspected the settling may have been aggravated by the use of concrete instead of asphalt for the interstate roadway. Although much longer-wearing, concrete has a tendency to settle more than its plain-Jane cousin, asphalt, because it's heavier.

Rockrimmon Constructors quickly ripped up the concrete roadway, brought in new fill dirt, compacted it and then repaved the roadway, believing that would solve the problem.

It didn't.

Now, Rockrimmon engineers have determined the settling problem is caused by unstable earth far deeper under the roadway, said Bob Wilson, spokesman for the Colorado Department of Transportation.

The problem is at its worst on the right side of the northbound lanes, but settling has occurred in the center and left lanes, too.

Crews in December began ripping up the concrete in the right lane and shoulder and will be adding even more fill dirt under the roadway base. Once that work is done and the lane can be reopened, crews will tackle the other lanes. That means motorists should expect lane shifts and closures until the end of March, when the work is expected to be completed.

CDOT engineers will walk the area in February to assess the work.

Although an inconvenience to motorists, the work is not costing taxpayers anything. Rockrimmon Constructors is responsible for warranty work. The warranty on COSMIX will extend another year beyond the end of March.
Wilson said earth-settling problems are not unusual when building new roads. He said settling occurred in widening I-25 through Trinidad.

On a remotely related item, CDOT is having a problem with a high-tech de-icer system installed on both sides of the interstate near the Tejon Street exit south of downtown.

The system, installed about six years ago, senses both friction and temperature on the roadway. When both of those drop, nozzles in the road automatically squirt de-icer solution. The automated system isn't working, and it will be early to mid-spring before crews can fix it, CDOT's Wilson said. Meanwhile, CDOT snow plow drivers are using remote controllers - much like garage door openers - to signal pumps to squirt de-icer onto the roadway.