Prominent design features of the project include:
Presidio Parkway High Viaduct
Replacing the 1,400-foot-long viaduct section approaching the Golden Gate Bridge with a modern viaduct. This is a challenging task from both an engineering and construction planning perspective. The new viaduct is a critical transportation link situated in a geotechnically complex environment within a seismically active region. During the construction phase, careful planning will be required to minimise interference with the daily commute of 100,000 vehicles.
Battery Tunnels and Main Post Tunnels
The Battery Tunnels (800ft. long) and Main Post Tunnels (1,000ft. long) are twin-bore cut-and-cover tunnels (three lanes in each direction) running parallel to the existing bluff. The use of lengthy cut-and-cover tunnels, combined with extensive landscaping, will dramatically reduce the impact of the Doyle Drive Replacement Project compared to the existing roadway. Pedestrian and bicycle continuity will be restored across the Presidio National Park, reconnecting its waterfront and inland areas.
Tunnel Systems Substation
Another complex element of the project was designing the tunnel systems substation which, due to the lack of available space and the project's strict architectural criteria, needed to be hidden within the structure between the newly built Presidio Viaduct and the Battery Tunnel. This substation will house the extensive systems needed to run tunnel lighting, electrical, fire suppression, and jet fans. With the use of 3D modelling, project designers developed a more efficient, integrated design to reduce bends in the rigid conduit being used.
Girard Road Interchange and Park Presidio Boulevard (Highway 1) Interchanges
One major new interchange will be created and another modernised as part of this project. These interchanges are designed to improve roadway geometry while minimising footprint and impact. Their design is optimised to meet current and projected traffic flow patterns and to match the capacities of approach streets. It also incorporates traffic calming features to better transition drivers between freeway and city driving environments.
Quartermaster’s Reach Viaduct
The Quartermaster’s Reach Viaduct is a 400-foot-long viaduct section that crosses a former, filled-in wetland area. Long-term planning for the Presidio includes excavation of this area and restoration of the brackish wetland and areas upstream.