WHAT HAVE BEEN ACCOMPLISHED:

JMEC has been prime design professional for designing the replacement of one of the two bridges under the Federal HBP and in accordance with Caltrans LAPM. The two projects are funded by the California Department of Transportation (Caltrans) through the Federal Highway Bridge Program (HBP), hence will require both compliance with the National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA). The Town is the lead agency for CEQA compliance; Caltrans, as assigned by the Federal Highway Administration (FHWA), is the federal lead agency for NEPA compliance.

The 24-foot long x 22-foot wide bridge, which carries Old La Honda Road over a drainage swale, is replaced by installing a 84-in reinforced concrete pipe culvert below the existing bridge and backfill with concrete around culvert from the outside edge of the exterior girders, up to the bottom of the existing reinforced concrete T-beam bridge deck. The inside of the pipe is partially filled with native materials and natural substrates per the recommendations of the RWQCB. Headwalls at each end of the pipe will be supported by reinforced concrete footings and CIDH piles. This structure type is required to preserve the existing historical nature of the bridge and to maintain one traffic lane during construction. The culvert also waives the current Caltrans new bridge requirements for bridge width and bridge barriers, allowing the Town to keep the historical bridge railings.

Due to deterioration and substandard load carrying capacity, load rating was performed on existing bridge using CSiBridge to determine probable load capacity.

Schedule:  Construction was completed in 2020

Special Issues:  The existing bridge was badly deteriorated beyond repair with corroded reinforcement and exposed reinforcement and spalling concrete. Complete bridge replacement was not feasible due to right-of-way with new constraints and the local historical significance of the bridge. The solution was to turn the existing bridge into a concrete culvert and fill the voids between the new RCP and existing bridge with lean concrete. Construction impact was minimized and through traffic was maintained except when moving materials and equipment. The existing concrete strength was field tested by Schmidt Rebound Hammer and embedment lengths of drill and bond dowels were adjusted to satisfy design requirements.

Feedback:  The local residents and the bicyclists have good review about the improvements.