SANDAG Stabilization Project Along Rail Corridor
San Diego Association of Governments (SANDAG) construction crews have reached another milestone by successfully grading the Del Mar bluffs and constructing a foundation that will strengthen the bluffs and rebuild the slope from the ground up.
“Stabilizing the Del Mar Bluffs is crucial to ensuring safe and reliable rail operations and creating a faster, fairer, cleaner transportation system through SANDAG’s 2021 Regional Plan,” said SANDAG Chair and Encinitas Mayor Catherine Blakespear.
Since 2003, SANDAG, in conjunction with the North County Transit District (NCTD) have been working in phases to stabilize portions of the coastal bluffs in the City of Del Mar. Routinely impacted by waves, wind and urban water runoff, the bluffs are an integral part of the 351-mile Los Angeles – San Diego – San Luis Obispo (LOSSAN) rail corridor.
This important stretch of railway has been an economic lifeline for the San Diego region and a key connection between Mexico and the United States. Used by Amtrak, COASTER, Metrolink and BNSF freight trains, both freight and passengers travel between San Diego County to Los Angeles and other points farther north. It is the second-busiest intercity rail corridor in the United States, serving 7.6 million passengers and moving $1 billion in goods and services each year.
Construction of Phase 4 occurred from May 2020 to January 2021. HNTB, an infrastructure design firm that provides innovative transit and rail solutions to the nation’s largest transit authorities, was awarded Project of the Year by the American Public Works Association for the design and implementation of this phase.
Improvements included the installation of additional support columns to stabilize localized areas and sea walls, construction of a drainage channel on top of the bluffs, repair of concrete channels and storm drain outfalls, and stabilization of existing headwalls.
When a portion of the bluffs collapsed in February 2021, train traffic was briefly halted and $11 million in emergency funding was obtained through a combination of state and local funds. With recent emergency work to the keyway at the base of the bluffs just south of Fourth Street now complete, crews will now begin construction of a new seawall, placing dirt at the base of the bluffs and building a new slope upwards.
To help prevent erosion, wooden beams known as lagging, will be placed between the exposed portions of the soil piles to create the seawall. The anticipated completion date for this part of the project is Fall 2021.
Phase 5 is anticipated to begin in early 2023; it is currently funded through construction and will address additional seismic and general stabilization needs. Phase 6 will continue to provide long-term rehabilitation and stabilization work, including protecting the base of the bluffs against additional bluff retreat.
With an estimated increase of 78 passenger trains and 22 freight trains traveling through this region by 2030, the stabilization of these bluffs will ultimately impact rail line reliability.
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