CDOT photo shows the old steel truss bridge on US 34 in Big Thompson Canyon while it was being dismantled last week. The new bridge opened Thursday night, four days ahead of schedule.

By Kevin Flynn
Inside-Lane.com

SEMA Construction once again completed the replacement of an aging steel truss bridge on U.S. 34 in Big Thompson Canyon four days ahead of schedule, reopening the major route between Estes Park and Loveland Thursday night – and completing the $3.8 million project.

SEMA replaced two bridges, including one that was the single poorest rated bridge on the state highway system (see photo of old bridge here), during two separate closures of U.S. 34 that were supposed to last 12 days each but wrapped up in eight.

“This is a huge accomplishment as it usually takes months to replace a bridge, but by prefabricating much of the new bridge and working nearly 24 hours a day, we were able to complete the new bridges ahead of schedule,” said Scott Ellis, resident engineer for the Colorado Department of Transportation.

The bridge that was completed Thursday is the downstream one of the pair. The upstream bridge was replaced in February. During the two closures, CDOT had recommended a route through Lyons via CO 66, with a net difference in distance of 16 miles between Loveland and Estes Park.

While the two bridges are structurally complete and available for traffic, SEMA still has minor work over the coming months to wrap up the project. It still has some drainage structures to install and asphalt paving to complete, which cannot occur until the weather gets warmer. It also has some guard rail installation to finish.

When that work starts, motorists will encounter some single-lane alternating traffic at the work sites, but no full closure.

The upper bridge that was replaced was rated 6 on a scale of 100 for structural deficiency, the lowest on CDOT’s list of bridges needing to be replaced – and the only one rated in single digits. Its companion downstream was rated 34. Both bridges were built in 1937 and were the last two remaining steel truss bridges in the canyon. U.S. 34 crosses 11 bridges in the canyon.

CDOT started the year with 124 poor-rated bridges on its system. Many of them will be replaced with revenue from the FASTER bill passed last year that levied new bridge and road safety user fees on vehicle registrations to dedicate to the work. The U.S. 34 bridges were replaced, however, with regular CDOT funding allocations.

Check out the map below to see all of the bridges on the poor-rated list. Click on the blue balloons to see each bridge, complete with pictures and descriptions including year of construction and where each bridge stands in the replacement process.

View Colorado’s Poor-Rated State Highway Bridges in a larger map