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Crews working on repairing Highway 36 during a mid-July evening following the collapse.
Crews working on repairing Highway 36 during a mid-July evening following the collapse.

Highway 36 Investigation and Plan to Prevent Future Collapse

Editor's note: The Colorado Department of Transportation has announced that as of Friday morning, October 4, all lanes are open on Highway 36, following completion of the actions described below. Continue for our previous coverage.

In July, barely three years after the completion of a major express-lanes project, a section of U.S. Highway 36 collapsed, causing a closure of the route between Denver and Boulder for days and resulting in lane reductions from three to two both eastbound and westbound ever since. But that's about to change.

Weather permitting, eastbound and westbound traffic will be reduced to a single lane tonight, October 1, with the same drill for tomorrow night, October 2, in order to complete repairs on the roadway between Wadsworth Boulevard and 104th/Church Ranch Boulevard. By the morning of Thursday, October 3, those traveling in either direction should have three lanes at their disposal: two for which there's no charge, and a third that carries a toll.

For the Colorado Department of Transportation, the speed with which this massive undertaking has been accomplished is a point of pride, and no wonder. Unlike the Central 70 and C-470 projects, which have recently announced sizable delays, the Highway 36 task is being completed on the shorter end of projections.

But that doesn't mean questions about why a segment built a few years ago (the express lanes project ran from July 2012 to the winter of 2016) crumbled so quickly. Lawrence Pacheco, spokesperson for Colorado Attorney General Phil Weiser, confirms that an investigation into what happened is ongoing. There's currently no timeline for its conclusion, but most observers expect a hefty amount of liability to fall on Ames Granite Joint Venture, the original contracting entity.

CDOT communications director Matt Inzeo draws a distinction between the inquiry by the AG's office, which is serving as the department's legal counsel, and the repairs. "One of the reasons we're in a place where we can reopen the road this week is because we've avoided focusing on blame and responsibilities," he says. "We're letting the investigation happen, letting those guys do their work, so we can focus on getting the road open again."

At the same time, Inzeo emphasizes that a different contractor was put in charge of the partial Highway 36 rebuild: Kraemer North America, which is also toiling on the current I-25 South Gap project. The following graphic outlines how Kraemer approached the challenge:

As Inzeo points out, "Just to the east of the site is a bridge over a railroad. That kind of bridge is typically taller than a lot of bridges, because you need to have more clearance to allow trains to pass underneath, and so there was an unusually high earthen ramp leading up to that. There was also an old wetlands nearby, so there were a couple of unique factors, and we think the clay layer in the soil got saturated and gave way."

To prevent the same thing from happening again, he goes on, "we used Geofoam, a product that's been used a few times in the state, but even more extensively in Utah. It's a high-strength foam, but it weighs less, so the load on the soil underneath is dramatically reduced. And we also drilled 140 caissons down to the bedrock right at the foot of the wall. That's a significant factor in safety, too."

By closing one lane each direction on October 1 and October 2 between 8 p.m. and 5 a.m., Inzeo says, "we'll be able to give crews a little bit of a buffer as they work on pulling back the barrier we've had up, then re-striping the lanes and getting back to the normal traffic configuration" — one that's been in place since the express lanes were installed.

There will still be tasks to accomplish after October 3. A bike path is supposed to be available that morning, but it's temporary. According to Inzeo, "The permanent bike path will be done when the project gets buttoned up" in December, after final touches are made to the wall and assorted fencing. "The path sits on a concrete pad, and as the engineers have explained it to me, that slab actually adds the weight and tension to hold the wall panels in. But the footprint of the final bike path is just a couple of feet over from where we're going to have the temporary bike path. In terms of travel distance, it will be virtually the same as what it usually is."

Getting to this point hasn't been easy, he admits. "The crews doing the permanent rebuild have been working 24/7, doing overnight shifts. They've been incredible, and that's why we're in a position where we're prepared to get traffic back to normal this week."

The next potential developments? A settlement or a lawsuit. For more help navigating Highway 36 and beyond, visit cotrip.org.

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