Sand replenishment starting at Ponto Beach in Carlsbad

Sand replenishment will start this week at South Ponto Beach, part of South Carlsbad State Beach on the Carlsbad-Encinitas city border, officials said.

The beach widening is a side benefit of the nearby Batiquitos Lagoon double-track project, part of a regional effort to add a second set of railroad tracks to improve train service along the 60-mile corridor between downtown San Diego and the Orange County border.

The San Diego Association of Governments is working with Caltrans to replace the 90-year-old, wooden, single-track bridge across the lagoon with a new steel-reinforced concrete structure wide enough to carry two sets of tracks.

Excavation of the channel beneath and near the bridge is expected to produce up to 60,000 cubic yards of sand over the next two years or longer, most of which will be trucked to the nearby beach, SANDAG officials said. About 8,000 cubic yards of the sand was used to expand a nesting area for California least terns just east of Carlsbad Boulevard, also known as Coast Highway 101 or the Pacific Coast Highway.

The California least tern is a white-and-black bird less than 10 inches long that breeds only in a few areas along the bays and lagoons of California and Mexico and is in danger of extinction because of coastal development.

Trucks carrying the sand from the lagoon to the beach will use Coast Highway 101 between La Costa Avenue in Encinitas and Poinsettia Lane in Carlsbad, usually between 7 a.m. and 5 p....