The detail in the Devil's Slide, Pacifica, CA, USA

On January 18, 2011, excavation of California Department of Transportation’s Caltrans) twin Devil’s Slide bores was successfully completed on State Route 1. This section of Route 1 is on an unstable mountainside that has a long history of road closures due to landslides. The 4,100ft-long tunnels will merge into a newly aligned roadway and then tie back into the existing highway. The tunnels were excavated using the Sequential Excavation Method (SEM). ILF Consultants was responsible for the SEM tunnel design and implementation during construction. The URS / Dr Sauer Corporation joint venture performed round-the-clock construction engineering and inspection services for the SEM tunneling works and is continuing to provide construction engineering support for the final lining work. Photos by: Zuzana Skovajsova of ILF Consultants.