California Incline Bridge and Idaho Avenue Pedestrian Overcrossing Replacements

Location: 

Santa Monica, CA

City or County Responsible for Project: 

City of Santa Monica

Award Category: 

Narrative Description Of Your Entry: 

Constructed by the City of Santa Monica, working closely with Caltrans, the California Incline Bridge and Idaho Avenue Pedestrian Overcrossing (Idaho Avenue POC) are two interrelated bridges that replace deteriorating, seismically deficient structures. The California Incline Bridge is a major connector street, beginning atop the steep slopes of Pacific Palisades Park and carrying vehicles, pedestrians, and bicyclists down to Pacific Coast Highway (PCH) at the base of the bluffs near Santa Monica State Beach. The 750-foot-long bridge has a total width of 52 feet to incorporate a new barrier-separated, multiuse bicycle/pedestrian path. Project challenges included a tightly confined construction site and the protection of erodible bluff slopes in an urban environment alongside the PCH. The bridge was designed to accommodate the site’s corrosive marine environment and high seismic demands, including up to 18 feet of potential bluff erosion that could occur over its 75-year life span. A high-resolution LIDAR laser survey of the bluff face was performed to produce the design of the bridge and special falsework. Since the bluffs are a protected resource, the bridge spans and 96 deep concrete piles were specifically located to minimize damage and erosion. Over 1,000 soil nails were installed in the slopes above the roadway to increase stability and seismic resilience. The project also called for the replacement of a 12-inch water main in the roadway and under the bridge. The waterline is placed in a protective casing to allow replacement from either end without damaging the bridge. Additional drainage inlets were also added to the roadway. Aesthetic elements include a replicated balustrade railing maintaining the historic features of the original bridge. The Idaho Avenue POC emerges seamlessly from the historic Idaho Trail and spirals tightly around the vertical clearance envelope of the California Incline to connect to a new bicycle/pedestrian path. The sculptural profile resembles a nautilus shell, facilitating a connection to the Pacific Ocean. Its primary architectural feature, the curved V-pier on the west side of the roadway, provides a “window” to views of the Santa Monica pier and ocean. The overcrossing transitions from the trail grade to a code-compliant staircase that integrates smoothly into the bridge, progressively widening on the descent into a grand staircase. Project challenges included working with an existing trail with a steep 10% grade, space limitations over the California Incline, the bridge location between steep, erodible cliffs and the City property line, and a large elevation drop between the trail and roadway. Completed on schedule and under budget, the California Incline Bridge and Idaho Avenue POC are constructed of corrosion-resistant concrete, reducing long-term maintenance, and feature LED lighting, reducing operating costs. User benefits include significantly improved safety, ease of use, and panoramic ocean views.

Submitted by: 

Zach Pollard, PE

Title: 

City Civil Engineer/Project Manager

Organization: 

City of Santa Monica

Address: 

1437 4th Street, Suite 300, Santa Monica, CA 90401

Phone: 

310-458-2200

Fax: 

Email: 

zach.pollard@smgov.net

Leave a Reply

Your email address will not be published.