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Bluffs Along Del Mar Train Tracks Present Dilemma For Transit Authorities

The rail line through Del Mar, close to where bluff collapses this year have ...

Photo by Alison St John

Above: The rail line through Del Mar, close to where bluff collapses this year have caused temporary closures, Dec. 11th, 2018

The North County Transit District is hoping to hear this month about an $18 million federal grant that would help stabilize crumbling bluffs next to the railway line through Del Mar.

The steep bluffs that edge the rail line along the beach in Del Mar have collapsed several times this year, leading to questions about how safe it is to travel by train up the North County coastline. Engineers are keeping a close eye on the bluffs because it could be decades until money is found to move the train tracks inland and underground.

Fifty trains a day use the scenic line between San Diego and Oceanside. Jim Linthicum, director of mobility at the San Diego Association of Governments, the regional planning agency, said it is also vital to keep it open for connections with Los Angeles.

“That is the only north/south rail line that connects us," he said. "That’s the second busiest intercity rail corridor in the country, and so a lot of people depend on that. It’s not just commuters, it’s all Amtrak to points north, and also the freight trains, so it would be a pretty significant impact to everyone.”

Stabilizing bluffs

The latest bluff collapse occurred earlier this week and caused brief delays. But Linthicum said the collapse was on the beach side of a berm that separates the track from the shore and was 30 to 40 feet away from the track itself. He said SANDAG and the North County Transit District have already spent about $20 million stabilizing the bluffs, including about $5 million on “soldier piles.”

“We have been driving what’s called soldier piles just a few feet away from the tracks,” he said, “and those are three-foot in diameter, reinforced concrete piles that go down, some as long as 65 feet down from the top of the bluff, down into good solid ground — and those hold back the tracks.”

The round tops of the soldier piles are visible in some places to the west of the tracks.

Photo by Alison St John

The top of a "soldier pile" used to stabilize bluffs next to the train tracks in Del Mar. Dec 11th, 2018

Sea level rise is happening faster than predicted, which erodes the bottom of the bluffs. Scripps Institution of Oceanography researcher Adam Young said the Del Mar bluffs erode about six inches a year on average, but often in unexpected chunks. After more than a year with no major falls, this year part of the bluff has already lost more than six feet in a number of falls that began in August. Young could not predict how long the bluffs could be stabilized to protect the railway line but said it would be prudent to move the line “sooner rather than later.”

Linthicum said the drought combined with heavy rains and ocean action at the foot of the bluffs are more responsible for collapses than the vibrations of the trains that pass along the top.

He said it should be possible to stabilize the bluffs for another couple of decades until money is found for the long-term plan to build tunnels for the train to pass under Del Mar.

Long-term plans

North County Transit District Engineer Stephen Fordham said several alignments for an underground tunnel have been suggested. But the tunnel option is tentatively proposed for 2050 at an estimated cost of more than $3 billion.

Photo credit: SANDAG

Optional routes for tunnels to carry rail traffic through Del Mar. Presented to North County Transit District board, Nov 15th, 2018.

“So that’s a significant amount of money,” he said. “I liken the stabilization project to if I currently want a fancy vehicle — I need to maintain my existing vehicle while saving money for my Lamborghini, I’m going to maintain my Toyota Camry. So we need to put our focus and stabilize the bluffs for rail traffic up through 2050 or until we have a funded project.”

No one is proposing to put a second train track along the Del Mar bluffs. That means the two-mile stretch will remain a bottleneck in the coastal corridor, which is currently being double-tracked so trains can pass each other between San Diego to Oceanside, at a cost of close to a $1 billion, Fordham said.

Fordham said the track is inspected twice a week, plus every time there is an incident like a bluff collapse. He is confident that it is safe.

“I’d ride the train today,” he said.

Next year he plans more drainage improvements. If NCTD lands the $18 million federal grant, that would go some way toward the estimated $70 million to $80 million estimated total cost of stabilizing the bluffs in coming decades.

“We’re trying to get consensus on our board and in our community,” said SANDAG’s Linthicum. “Should the tracks be stabilized in place, should they be moved inland, and - is the public willing to spend the money to move the tracks inland?”

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