CA: Railroad’s failing retaining wall near Mission Bay needs emergency repairs

Emergency repairs are needed for a failing retaining wall on one of the busiest sections of the only railroad connecting San Diego with Orange County, Los Angeles and the rest of the United States.

The concrete wall was built as part of the $95 million Elvira to Morena double-track completed in 2020, according to the San Diego Association of Governments, the region’s planning agency. The project added 2.6 miles of a second main track between state Route 52 and Balboa Avenue, along with new railroad bridges, traffic signals, and utility and drainage improvements.

The 2,604-foot-long wall, up to 24 feet tall, is built in rectangular sections along Santa Fe Street near Damon Avenue east of Interstate 5 in Clairemont near the northeast corner of Mission Bay.

The railroad above the wall carries two sets of double tracks. One set is used by the Metropolitan Transit System’s light-rail trolley system and carries the Blue Line that serves the UC San Diego main campus and other nearby destinations. Another set of double tracks carries North County Transit District’s Coaster commuter trains, Amtrak and BNSF freight.

“NCTD is aware of the necessary improvements that need to be made to the retaining wall … and is collaborating with SANDAG on the improvements,” NCTD Chief of Staff Mary Dover said in an email Thursday.

“At this time, NCTD does not anticipate that the improvement project will result in any impacts to passenger rail operations through the area,” Dover said.

“Monitoring equipment has been installed on and adjacent to the wall which provides real-time notification on movement of the wall,” she said. “SANDAG and NCTD are monitoring this data to verify there are no changes to conditions that warrant modifications to passenger operations.”

A preliminary estimate indicates emergency repairs could cost $15 million, SANDAG CEO Mario Orso said recently. The money is available in the agency’s capital reserve fund.

“The need for additional monitoring was brought to our attention by NCTD during the fall of 2022. Additional monitoring was conducted between fall 2022 and winter 2024,” SANDAG officials said in an emailed response to The San Diego Union-Tribune’s questions.

“In winter 2024, the monitoring revealed slope movement of concern and further analyses were initiated to gain a deeper understanding of the movement,” the email states. “Once these studies were completed in May 2025, SANDAG began emergency stabilization work on the retaining wall.”

Design alternatives are being developed and evaluated, officials said. About 300 feet of the wall appears to be affected so far.

“Preliminary geotechnical findings indicate that emergency stabilization work is required,” officials said. “SANDAG is conducting daily monitoring of the retaining wall. A full analysis is underway to determine the root cause and extent of wall movement.”

On Wednesday, one of Santa Fe Street’s two lanes was closed below the wall, as employees from the consulting firm Stacy Whitbeck with trucks and a drilling rig bored deep beneath the roadway to take ground core samples.

A notice SANDAG issued early in the week said workers will be directing traffic on Santa Fe as work proceeds between 7 a.m. and 7 p.m. weekdays for about the next four months.

Double-tracking is intended to improve the safety and efficiency of rail traffic, allowing more trains and faster service. So far, SANDAG has added a second set of tracks on more than three-quarters of the 60-mile route from Santa Fe Station in downtown San Diego to the Orange County border, with plans to eventually double-track the entire route.

SANDAG has been battling instability for more than 20 years in at least one other area — about 1.7 miles of track on the eroding coastal bluffs at Del Mar.

A fifth phase of stabilization work, including the construction of seawalls, soldier piles, and drainage structures, is underway in Del Mar. SANDAG’s long-term plan calls for moving the tracks off the bluffs into a tunnel bored beneath the city’s steep hillsides. Construction costs have been estimated at up to $5 billion, with completion no sooner than 2035.

Del Mar is one of the remaining bottlenecks in the rail corridor where SANDAG has been unable to add a second set of tracks because of the limited space available.

Another bottleneck is at San Clemente, where several miles of track follow the edge of the beach near sea-level.

The Orange County Transportation Authority, which oversees the rail corridor there, recently completed emergency repairs to a rock revetment that protects the tracks from coastal erosion. Beach replenishment also is planned, but the narrow right-of-way through San Clemente includes no room for a second set of tracks.

OCTA officials recently began studies of possible solutions for the long-term protection of the segment through San Clemente. One idea sometimes discussed is to reroute about seven miles of track inland, perhaps along the I-5 freeway, but little progress has been made in that direction.

The San Diego and San Clemente segments are on the southern end of what’s officially known as the Los Angeles- San Diego- San Luis Obispo, or LOSSAN, rail corridor.

The railway also is part of the Defense Department’s nationwide Strategic Rail Corridor Network, which consists of 38,800 miles of track serving 193 military installations.

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