Project No. 347 – CR 56 Bridge Replacement North of State Highway 287

CR 56 Bridge Replacement:

Larimer County is replacing a bridge on County Road 56 near Highway 287.  The existing bridge, originally constructed in 1930, was rated “poor” when last inspected in 2023.

While several different structure types were investigated for the replacement, an aluminum box culvert was ultimately selected.  The aluminum box culvert is a long term and cost effective solution for this relatively low volume gravel road and comes with the added benefit of being able to be constructed in-house by Road and Bridge crews adding to the cost savings over other structure types.

The existing bridge structure is a timber superstructure supported by a stone masonry substructure, both of which had seen significant deterioration over the past +90 years.

The Larimer County Road and Bridge and Engineering Departments worked together to select a consultant to provide a new bridge and road design and then worked to select a vendor to provide the aluminum box culvert.  Permits were obtained from the State of Colorado and the Irrigation Company and construction began in October of 2024.

The road is being slightly re-aligned in order to improve the tight curvature through the structure which has allowed the existing structure to remain in place during construction of the new structure helping to improve construction access to the site.

The structure erection is complete (+10,000 bolts installed) and we are working on backfilling the structure.  Following the completion of backfilling, we will install the new roadbase surfacing, install new guardrail, and remove the old bridge structure.

We are currently scheduled to complete the project and open the road in February.  Seeding and final restoration will occur in the spring of 2025.