A proposal to place the railroad tracks in a trench at the edge of the bluffs in Del Mar raises “serious concerns” about erosion and access to the beach, according to the California Coastal Commission.

“This new potential alternative ... would hamper efforts to plan for sea-level rise and erosion, thereby resulting in the loss of significant public access and beach resources,” said the commission’s Zach Rehm, a senior transportation program analyst, in a letter to the San Diego Assn. of Governments.



For the record: An earlier version of this article said the cost of the proposed bluff trench was less than $400,000. It’s less than $400 million.

The bluff trench is one of several ideas being considered by the area’s regional planning agency to safeguard the tracks at the edge of the eroding coastline.