Hospital Road Bridge Low Water Crossing Replacement Project

The $10.6M Hospital Road Bridge Low Water Crossing Replacement Project realigned Hospital Road and replaced the existing low water crossing with a new bridge spanning across the San Benito River, providing safe public access for existing and future residential and commercial properties, and facilitating improved emergency vehicle response time in the area.

The project constructed a 580-foot-long, cast-in-place (CIP), post-tensioned box girder bridge and approximately 2,400 feet of new roadway approaches and improvements. Located west of State Route 25 to the south of the City of Hollister, the Hospital Road realignment and bridge is situated directly to the north of the existing low water crossing. The new bridge provides two 12-foot-wide travel lanes and two 5-foot-wide shoulders meeting the requirements of both Caltrans and County design standards. Abutment foundations are supported on 16-inch steel pipe piles (Class 140, Alt W), and each pier consists of two 48-inch pier columns built integrally with 72-inch cast-in-steel-shell (CISS) piles. Drop bent caps were utilized at each pier to facilitate structure deflections under seismic conditions.

The bents are founded on 72-inch diameter cast-in-steel-shell (CISS) piles ranging in length from 94 to 104 feet. Difficult driving conditions and pile driving refusal necessitated revising the pile tip elevations. Key environmental issues included impacts to the bank and channel of the San Benito River, protected trees, sensitive riparian habitat (e.g., mulefat thickets), and special-status wildlife species. Typical special-status wildlife species at the site include South Central California coast steelhead, California red-legged frog, California tiger salamander, western spadefoot, western pond turtle, San Joaquin whipsnake, western burrowing owl, American badger, and San Joaquin kit fox.

A primary project challenge was constructing the bridge within the limited four-month window (June 15 to October 15) that allowed for work to be performed within the river channel. Hence, even a small delay in critical path activities could have caused the project to lose the short work windows in any given year, necessitating an eight- to a nine-month waiting period or delay until another window became available the following year. Additionally, the project had many project stakeholders including the County, City of Hollister, Caltrans, California Department of Fish and Wildlife (CDFW), National Marine Fisheries Service (NMFS), US Fish and Wildlife Service (USFWS), US Army Corps of Engineers (USACE), Regional Water Quality Control Board (RWQCB), utility companies, and local residents. Therefore, the key to the timely completion of this project was anticipating and proactively resolving construction and coordination challenges before they turned into delays.

The project was funded under the Highway Bridge Program (HBP) administered by the Federal Highway Administration (FHWA).

MNS provided construction management services, including construction inspection, office engineering, and Stormwater Pollution Prevention Plan (SWPPP).