The $34-million Laguna Niguel-San Juan Capistrano Passing Siding project moved a step closer to construction as HNTB Corporation recently completed the final design and engineering phase for the job, and the Orange County Transportation Authority’s (OCTA) Board approved a notice to proceed (NTP).  

The project adds 1.8 miles of new passing siding railroad track between the Laguna Niguel/Mission Viejo Metrolink Station and Trabuco Creek in San Juan Capistrano, Calif. The passing siding track will run adjacent to the existing track, allowing trains traveling in opposite directions to pass each other without stopping. When complete, project officials say it will reduce delays, increase safety and provide more reliable rail service on the Los Angeles-San Diego San Louis Obispo rail corridor, also known as LOSSAN.

Other project improvements include relocating a spur track; improving the private crossing from Camino Capistrano to Saddleback Rancho Capistrano; and re-profiling approximately 600 ft of Camino Capistrano to improve roadway safety.

The HNTB design and engineering team, led by Graham Christie, PE, HNTB Southern California rail leader and associate vice president, prepared the final design for the passing siding, roadway improvements and associated structures. HNTB started the design in March 2015 and completed it in summer 2018. Christie says the project was delayed for nearly a year and a half due to issues with approvals related to the private at-grade crossing associated with the project.

To get the project rolling, the HNTB team must first deal with an old railroad bridge they want to replace with a concrete, precast box culvert, says Christie.

“The existing bridge is a short, 3-span, singled tracked timber trestle on timber piles and Metrolink prefers concrete solutions for short span bridges which typically have longer economic lives than timber structures,” says Christie.

He says there are more than 40 intercity, commuter and freight trains that pass over the bridge each week day and the operating railroads (Metrolink, Amtrak, LOSSAN, and BNSF) expect to maintain regular, dependable train service especially during the week. “So our design needed to help minimize disruptions to the railroad,” he says.

Christie says to minimize disruptions his team will replace the bridge during a weekend, when train traffic is about 50 percent less than average.

“Our design uses a concrete box culvert that can fit under the center span of the existing bridge,” he says. “The contractor (Reyes Construction) can prepare the necessary foundation improvements and install the concrete box culvert ahead of the weekend outage which will help to minimize work that is required during the weekend shutdown.”

Construction on the project is expected to begin by next month and is anticipated to take up to two years to complete.