SANDAG Selects Three Options for Del Mar Train Tunnel

Written by David C. Lester, Editor-in-Chief
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Courtesy of HDR

SAN DIEGO –– The San Diego Association of Governments (SANDAG) announced that three routes have been offered for consideration for a tunnel to provide a long-term solution to bluff erosion.

The San Diego Tribune reports that approximately 20 routes were initially considered. After significant work, the agency narrowed the options to three.

RT&S has covered the ongoing saga of geological instability impacting the southern California coast for several years. A quick search of our archives will reveal stories providing strong detail on what’s been going on. You can find many of those stories through this link.

Transit leaders say that with the bluffs eroding at a rate of six inches per year, a rate due in part to climate change and rising sea levels, the situation has reached a critical point.

Keith Greer, SANDAG’s deputy director of regional planning, remarked that “This is the face of adapting to climate change.”

The selection of these three proposed tunnel routes will be part of a draft environmental impact report being prepared for the project. The recent announcement of the three routes will allow 45 days (through July 19) for individuals to prepare written comments for inclusion in the draft EIS.

After over 20 years of work for temporary stabilization of the bluffs, this effort has now reached the fifth phase, which includes the installation of drainage structures on the face of the cliffs, additional seawalls, and more concrete-and-steel pilings.

Seawall construction at Del Mar Bluffs

While these efforts will be effective in the short term, engineers and officials agree that completely eliminating the coastal route and replacing it with an underground tunnel is the most stable approach. However, homeowners in the area have expressed concern over possible noise and vibration from trains running through a tunnel deep under their homes, along with possible impact on the value of those homes. Despite these concerns, deputy director Greer said that “We are not anywhere near the point of determining the properties that will be affected.”

Many readers will recall that the SANDAG route is part of the LOSSAN Corridor, which runs the 351 miles from San Luis Obispo, San Diego, to Los Angeles.

It’s important to note that there are several problem areas on the LOSSAN corridor, and Del Mar is just one of them. Another is at San Clemente, with tracks (about seven miles) caught between crumbling bluffs and a shrinking beach. This area has been plagued with significant landslides for years, generating huge clean-up costs.

The San Diego Tribune also reports that “A tunnel is necessary at Del Mar because the topography there is too steep for any train to climb over. To keep the tracks relatively level, the route will be as deep as 300 feet below ground [in] some parts of the city.” The San Diego Tribute goes on to say that “Another reason for the new route is that the narrow bluff-top right-of-way, owned by the North County Transit District, has no room to add the second set of tracks that NCTD needs to expand passenger and freight service. The tunnel would be built wide enough for two sets of tracks.”

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