DENVER - Temporary roads on badly damaged mountain highways will be in place by Dec. 1, after historic flooding rendered them impassable.
Gov. John Hickenlooper has called for temporary access to be complete before the winter.
On Thursday, the Colorado Department of Transportation revealed the damage to major roadways in Boulder and Larimer counties.
- 85 percent of U.S. 34 is a total loss
- 50 percent of Highway 7 is a total loss
- 40 percent of U.S. 36 is a total loss
- 20 percent of Highway 119 is a total loss.
"This is unprecedented, at least in my career with CDOT, that we have to do something of this magnitude," said CDOT engineer Corey Stewart.
7NEWS has learned that CDOT will start accepting bids on Friday morning for the temporary fix to U.S. 34.
"We don't even know if the roadway is safe to drive on to access the site," said Stewart. "The flood waters washed out portions of the roadway, got underneath the wall and basically removed all the embankment that supports the roadway."
Aerial images show much of the retaining wall next to the Big Thompson River still intact, but CDOT will likely have to replace the structure.
"The water's actually flowing behind the wall," said Stewart. "We think we have to get a geotechnical engineer into the site to assess whether we can even salvage the wall."
Much of the U.S. 34 pavement is missing, revealing the horizontal tiebacks that hold the wall in place by connecting it to the mountain rock.
The temporary fix on U.S. 36 between Lyons and Estes Park will begin next week.
"National Guard is coming in and will start rebuilding the road bed, for a temporary road on that roadway starting Monday," said Stewart. "They can probably get that done in a month to two months."
On U.S. 36 in Lyons, a bridge going over the St. Vrain is still standing, but is badly compromised. The rushing water scoured the supports and the bridge is basically standing on stilts.
The temporary fix will include an Erector Set-type temporary bridge that will be installed about 10 feet on either side of the current bridge. The temporary bridge could be in place in the next two weeks.
The temporary roads may be paved, but they may also be gravel.
"We don't know, at this time, if we can get it fully paved," said Stewart. "There's a good chance that there will be pieces of it that will have to be speed reduced. It will not be a driving service similar to the roadway before the floods happened."
If there is any good news, CDOT found many of the bridge structures still standing.
"The design for our bridge structures were able to handle in excess of what we would have designed those to handle," said Stewart. "It's exceeded a 100-year event all over. The (U.S. 34) wall, it's still there, but from our assessments we've determined in some locations that we've had as much as a 500-year event."
Even though the temporary fixes should be in place by the end of the year, the permanent work will likely be years away.
After the 1976 Big Thompson flood, temporary roadways were built in a few months, but it took 3 to 4 years to reconstruct U.S. 34.
"I don't think it would be an inappropriate estimate to assume that it could take an additional 3 to 4 years to get back to a position of a permanent fix," said Stewart.
CDOT has already pledged its $100 million contingency fund for emergency repairs. The Federal Highway Administration has provided $35 million.