Five years of construction of the $1.1 billion Presidio Parkway in San Francisco is drawing to a close as the project moves towards final landscaping over the twin sets of twin running cut-and-cover tunnels that are enabling transformation of the Presidio waterfront area between the iconic Golden Gate Bridge and Downtown San Francisco.

“As the first PPP project approved by the California Transportation Commission, the Commission is pleased to see the timely delivery of the Presidio Parkway P3 project – a project that demonstrates innovation in funding and project delivery,” said California Transportation Commission Chair Lucetta Dunn.

Although the new Doyle Drive is open, construction activity will continue into mid to late 2016 and will include removing the temporary bypass around the Main Post tunnels, reconstructing Halleck Street, and covering and landscaping all four tunnels so that pedestrians and cyclists can access the waterfront and park.

The delivery consortium’s equity partners are Hochtief PPP Solutions North America and Meridiam Infrastructure SCA, with US construction firms Kiewit and Flatiron as lead contractors and HNTB as lead designer. Funding for both phases is via a mixture of low interest Federal loans, Federal stimulus package funding, Prop K sales tax receipts and contributions from regional and local transportation agencies. Under the terms of its design, build, operate, maintain and transfer agreement with Caltrans and SFCTA the PPP concessionaire will receive payment of US$185 million at completion of Phase II, followed by staggered payments during the 30 year concession period.

Main structures of the Presidio Parkway project. The southbound Battery Tunnel (foreground) was constructed in Phase 1, along with the temporary bypass of the Main Post tunnels, to keep traffic moving during construction of the remaining tunnels

At the heart of the project are two pairs of shallow cast-in-place concrete cut-and-cover tunnels – the 850ft long Battery Tunnels and the 1,020ft Main Post Tunnels. The vertical cross section profile for all tunnels is approximately 16.5ft at the wall and 31ft vertical height at the crown, with raised sections to accommodate and support a longitudinal jet fan ventilation system. Three highway lanes and two shoulder lanes run through the northbound tunnels, with the southbound tunnels accommodating four highway lanes.

A temporary bypass of the Main Post tunnels construction site (built during Phase I) has been in operation since the start of Phase II construction in 2012 to facilitate installation of the cast-in-place structures. Earlier completion during Phase I of the southbound Battery Tunnel and High Viaduct that serves it, and the temporary bypass of the Main Post Tunnels site, has enabled bidirectional traffic flow to be maintained along a rerouted Doyle Drive.

A highway switch enabling full northbound and southbound usage of the completed Presidio Parkway route, all tunnels, and associated interchanges, had been scheduled in early June following a weekend closure to enable final connections to be made. This would have marked full vehicular operation of the Presidio Parkway for the very first time, although up to 12 months worth of landscaping over the concrete tunnel structures and work to remove the temporary bypass remains.

Connection to the iconic Golden Gate Bridge

However, the closure has been postponed to complete testing and software integration of the tunnel fire-life-safety, traffic and communications systems. These systems work in concert and include ventilation, heat detection monitors and a state-of-the-art water deluge system for fire protection. A new closure date will be announced when system software integration and testing is finished and certified by the State Fire Marshal.

Doyle Drive, which the Presidio Parkway is replacing, is the portion of Route 101 located within the Presidio of San Francisco, a National Park area. The roadway winds 1.5 miles along the northern edge of San Francisco, connecting the San Francisco peninsula to the Golden Gate Bridge and the North Bay. Each weekday, more than 100,000 vehicles travel between Marin and San Francisco, over the Golden Gate Bridge and along Doyle Drive.

The new Presidio Parkway replacement is based on a design that will improve the seismic, structural and traffic safety of the roadway. It will also be far more sensitive to community needs and the national park setting, reducing impacts on biological, cultural, historical and natural resources and on the surrounding neighborhoods.

The tunnels are an important part of the final design of the Presidio Parkway because they will enable pedestrians and cyclists to cross over the roadway below, resulting in new connections between the upper Presidio park area and the historic coastal defense batteries, Crissy Field and the waterfront.