Special to the Montrose Daily Press
The Colorado Department of Transportation and contractor Ralph L. Wadsworth Construction Co. have begun construction of a new bridge that will replace the historic structure on Colorado 92 over the Gunnison River.
Work began this week on replacing the bridge, which is located on CO 92 at Mile Point 6.42, just east of Delta and east of the CO 92 junction with Colorado Highway 65. During construction, a temporary bridge will allow motorists to continue using CO 92. Winter travel impacts are anticipated to be minimal.
The project includes repaving a section of CO 92. Repaving work will take place during summer 2022, and completion of the new bridge is expected in November 2022.
Bridge work and paving are both scheduled to minimize impacts to detour traffic from the US 50 Little Blue Creek Canyon Safety Improvements project. The US 50 project is located further south, between Montrose and Gunnison.
The new bridge will be a three-span concrete girder structure with two sets of concrete piers and will span the Gunnison River at the same location as it is today. The total proposed bridge span length will be shortened by roughly 17 feet and raised to accommodate freeboard requirements.
Designed for a 100-year lifespan, the new structure will be constructed with two 12-foot lanes, two 10-foot shoulders and standard bridge railing. The existing bridge is a 383-foot, three-span steel Camelback Pony truss built in 1938.
The 82-year-old steel truss bridge has both structural and functional deficiencies, making it eligible for funding through the Statewide Bridge and Tunnel Enterprise (SBTE), the government-owned business within CDOT that finances, repairs, reconstructs and replaces designated bridges meeting specific criteria (click here for more information).
The SBTE is funded through vehicle registration fees.Two spans from the historic structure will be adopted by the City of Delta and one by Montrose County.
Functionally, the bridge is too narrow to safely and efficiently handle the volume or weight of traffic it receives today. The structure is geometrically substandard and rated as “poor,” with a 30-foot width that is narrower than the 40-foot width of the roadway approach.
The current average daily traffic (ADT) across the bridge is 5,300; the projected 2040 ADT is 5,998. Its load capacity was reduced in 2016, rendering the structure in serious condition. The existing bridge also has the following structural deficiencies:
• The bridge has narrow, three-foot shoulders, providing only a small margin for error for vehicular travel across the structure. Additionally, narrow shoulders present a safety hazard for pedestrians crossing the bridge or for maintenance workers accessing the bridge next to traffic. The need for continual maintenance heightens safety risks for maintenance crews.
• The existing bridge has a sufficiency rating of 27 out of 100. In addition, the bridge is load restricted and is posted for low-truck-weight capacity.
• The bridge is at risk of scour, which is the removal of stream bed material caused by swiftly moving water from around bridge abutments or piers. The existing structure does not meet freeboard requirements (referring to the clearance for high water).
Currently, the Gunnison River flow hits the lower portion of the structure during periods of high flow, requiring CDOT maintenance crews to remove debris off the bridge following the event. In some instances, high-flow debris has damaged the structure, as well as its west pier.
• The concrete curbs have areas of deterioration and spalling, requiring patching in the past. The deck, piers and abutments have all experienced cracking; the stringers (longitudinal steel support beams) are rusted; and the trusses have extensive corrosion.
Initially, motorists may encounter single-lane, alternating traffic during daytime hours, Monday through Friday, as crews construct a two-lane detour and install a temporary bridge south of the existing structure. With this detour in place, CO 92 will remain open to vehicles — including trucks — during bridge construction.
The speed limit for the detour and temporary bridge will be posted at 55 mph to increase safety for both motorists and workers.
When surface treatment of CO 92 is underway in the summer of 2022, motorists will likely encounter single-lane, alternating travel during daytime hours — these details will be posted at a later date on the project website and on CDOT’s traveler information site.Project Information For additional information about this project:
• Call the project information line at (970) 901-2180
• Email the project team at: firstname.lastname@example.org
• Visit the project website at: https://www.codot.gov/projects/co92-gunnisonriverbridge