CO 92 Gunnison River Bridge Design Phase

About the Project

Gunnison River Bridge

The Colorado Department of Transportation is designing a new bridge that will replace the historic structure on CO Highway 92 over the Gunnison River. The existing bridge is a 383-foot three-span steel Camelback Pony truss built in 1938. It is located at mile point 6.42, just east of Delta and the junction with CO 65. The current 82-year old steel truss bridge has both structural and functional deficiencies, making it eligible for funding through the Colorado Bridge Enterprise (CBE), the government-owned business within CDOT that finances, repairs, reconstructs and replaces designated bridges meeting specific criteria. The CBE is funded through vehicle registration fees.

Project Schedule

Design Complete: May 2021

Construction Begins: November 2021

Projected Completion Date: November 2022

project map of co92

Project Priorities

  • 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. In addition, the bridge is load restricted and is posted for low-truck-weight capacity.
  • The existing bridge also has structural deficiencies, including 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.
  • 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.

What has been established through the design to date is that the new bridge will be a three-span concrete girder structure with two sets of concrete piers that 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. It will be constructed with two 12-foot lanes with 10-foot shoulders and standard bridge railing, while being designed for a 100-year lifespan.

Once construction begins, anticipated in November 2021, CO Highway 92 will not need to be closed to accommodate the work. A temporary two-lane detour will send vehicles, including trucks, over a temporary bridge installed on the south side of the existing structure. The speed limit for the detour and temporary bridge will be posted at 55 mph to reduce traffic impacts. The estimated completion date for the project is November 2022.