Repairs to the U.S. 50 bridge over the Blue Mesa reservoir could take anywhere from four weeks to several months after crews finish inspecting for additional cracks, state transportation leaders said Tuesday.
The Colorado Department of Transportation is considering four repair options, all of which depend on the extent of damage to Middle Bridge, a 1,500-foot-long bridge carrying U.S. 50 traffic over the lake, officials said during a community meeting in Gunnison.
Since the sudden April 18 shutdown of the bridge, which has complicated critical travel between Montrose and Gunnison, crews have identified 118 areas where ultrasonic testing needs to be conducted to determine the integrity of the steel bridge, said Jason Smith, a regional transportation director for CDOT.
Crews are about 40% complete with its inspection, officials said, calling it a “slow process” that involves scraping off the paint, grinding down or sandblasting the area and conducting ultrasonic testing on each location. Inspectors did not find any “visual issues” with the shorter bridge 2 miles to the west, made of the same type of steel, but will conduct further inspection in the future.
The ultrasonic testing results are then sent to experts to review and look for “anomalies,” Smith said. So far, 40 locations have been scanned and 25 anomalies have been found, he said.
Officials said they hope to get enough repairs completed before Halloween, when inclement weather would likely complicate or stop the work. The bridge is made of type T-1 steel, which is three times the strength of normal steel and makes repairs more challenging, Smith said.
The best repair option for the bridge will depend where and on how severe the anomalies are, Smith said.
The best-case scenario — and quickest option — for repairs involves attaching 12-foot plates in areas along the bridge where anomalies are found, said Jason Proskovec, a project manager with Kiewit Engineering Co., a company that has completed major infrastructure projects in Colorado, including the rebuilding of U.S. 34 in Big Thompson Canyon after the 2013 floods.
The worst-case scenario would be a complete replacement of the bridge’s three spans, which could require construction crews and engineers to work from man lifts and cranes in the water to make the repairs.
“I think right now it’s low probability, but it is still a possibility,” Proskovec said. Kiewit has already obtained the first 88 tons of steel needed for repairs, he said.
Keith Stefanik, a CDOT engineer, said he did not have an exact date as to when a single lane of traffic may be allowed over the bridge.
“Our short-term goal is to make enough repairs to get this open to some type of interval traffic. We’re not sure on that perspective yet, but we will weigh all the options on how we can repair it with traffic intermittently closed or how we can repair it with traffic closed at all times of the night,” Stefanik said.
“We need to know exactly what’s failing, what’s good, where the defects are, so that we can shore up this bridge and make the proper design decisions,” he said. “We will hit the ground running and make sure that we try to reduce the closure period of this bridge to the shortest range possible.”
State officials have discussed temporary options to get travelers from one side of the reservoir to another in the meantime — from ferries to floating bridges — but said their attention is focused on repairing the bridge.
The bridge closure has complicated critical commutes along the vital route that connects Gunnison to Montrose. Some students took a 30-minute ferry ride across the choppy waters to get to school. Gunnison Valley Hospital shifted to disaster management mode to figure out how to deliver critical care to kidney and cancer patients.
“The group’s consensus has been that focusing our immediate efforts on doing everything we can to fortify local groups is the best bang for our buck in getting more people to and from,” CDOT Director Shoshanna Lew said.
Starting Thursday, trailers and commercial vehicles under the Colorado legal maximum weight (85,000 GWR) will be allowed to join other travelers along the County Road 26 detour route. A pilot car will continue to guide traffic along the rugged, dirt road four times a day to local travel.
CDOT crews have spread thousands of pounds of gravel along the high mountain road that typically has between 100 to 125 cars during its peak traffic periods. Since opening the 87-mile detour route, traffic along the road has increased 40 fold, officials said.
Crews continue to work 10- to 12-hour days to clear Kebler Pass when weather permits, officials said. On Tuesday, the pass got 6 inches of snow and strong wind downed 16 trees across the road.
A date for reopening the pass is still unknown.
No oversize loads or hazardous materials will be allowed on County Road 26, also known as the Lake City cutoff. Transportation officials are advising prohibited vehicles to use two alternative routes — Interstate 70 to the north or U.S. 160 to the south.