Field Note: Sorrento to Miramar Double Track, Phase One

San Diego, Calif. – The Sorrento to Miramar Double Track project is the first of two phases of construction to speed passenger and freight rail services on the Los Angeles-San Diego-San Luis Obispo rail corridor. The project involves straightening part of the slowest, steepest, and highest-curve territory of any segment along the corridor. A wooden trestle bridge built in the early 1940s will also be replaced, and a new track crossover will be installed.

Flatiron proposed using innovative permanent soldier pile tieback walls on a portion of the project to owner SANDAG as a value engineering alternative to the conventional reinforced concrete walls, saving both time and money. The alternative wall design consisted of drilled-in soldier piles with temporary treated timber lagging between, and a permanent rock sculpted shotcrete architectural facing. Lateral support for the wall was provided by permanent tiebacks at taller wall heights. This wall system is traditionally constructed as a “cut” wall but was constructed successfully and economically as a “fill” wall in this instance. Project completion is expected in April 2014.