This project included roadway, hydraulic, and structural design services along US 36 and CO 7 in and near Lyons, Colorado. The improvements on US 36 covered roadway and structure repairs on a 10-mile segment of US 36, and 0.1-mile segment of CO 7. The extreme rainfall event in September 2013 caused damage to these roadway segments and several structures. At the request of CDOT, Muller’s engineers acted quickly to inventory the damaged roadway and structures, to determine where emergency fixes were necessary. Once the structures had been temporarily stabilized, Muller began to design permanent improvements.

A double-celled concrete box culvert carrying US 36 over Left Hand Creek was particularly hard-hit by the flooding. The floodwaters overwhelmed the structure and overtopped the highway, washing out the downstream wingwalls and creating a large scour hole at the downstream end. CDOT wanted to replace this undersized structure with a more resilient bridge that could convey the next major flood and associated debris and sediment. In response, Muller’s engineers designed a 155-foot single span prestressed I girder bridge to increase the hydraulic capacity for Left Hand Creek. The bridge and roadway were also widened to allow for auxiliary lanes at the Middle Fork Road intersection just south of the new bridge. The channel was armored with rock and gravel to simulate a natural stream bed and provide protection for the bridge foundations.