Twin Peaks Blvd Cold In-Place Recycling Pavement Renovation Phase 2

Location

Twin Peaks Blvd, San Francisco, CA

City or County Responsible for Project

City & County of San Francisco

Category

Roads: Efficient and Sustainable Road Maintenance, Construction and Reconstruction Projects.

Author

Ophelia Lau

Organization

San Francisco Public Works

Address

1680 Mission St, 4th Floor

Phone

415-554-8350

Project Description

Twin Peaks Blvd sits on top at one of the highest peaks of San Francisco, CA which provides a breathtaking view of the skyline of San Francisco. The area is frequently visited by tourists and many residents of the Bay Area. “Eureka” (North) and “Noe” (South) are the two peaks which the roadway wraps around to create the ‘Figure 8’ where stunning 360-degree views of the city and the surrounding Bay Area are showcased. With the frequent visitors and usage of the area, the approach was to utilize an emerging technology paving method of Cold In-Place Recycling (CIR) with an overlay which is environmentally-friendly and cost saving compared to a conventional grind and pave with Hot Mix Asphalt (HMA). CIR is paving the way to an innovative, greener technology and was deemed as a ‘sustainable pavements’, which has been defined as those pavements that are safe, efficient, environmentally friendly meeting the needs of present-day users without compromising the needs of future generations. CIR process utilizes the existing wear surface and additional material/additives to recycle 100% of the existing asphalt pavement. CIR compared to HMA method: • Producing little to no off-haul – no need to dispose of material after full utilization of existing asphalt • Reduction of 90% truck traffic in construction, which meant less impact on traffic and less damage to the roads caused by heavy vehicles in the busy streets of San Francisco. • Producing 52% less greenhouse gas emissions • Conserving 62% of energy from the production, transport, and placement of materials • Minimizing construction time • Saving 32% of construction costs compared to HMA with localized base repair San Francisco Public Works collaborated closely with the San Francisco Municipal Transportation Agency and San Francisco Recreation and Parks to complete a thriving environment for locals, tourists, wildlife, and vegetation. Improvements from interagency coordination included: • Repaving Twin Peaks Blvd using green technology • Limiting vehicular access to the ‘Figure 8’ for improved bicyclist and pedestrian safety • Renovating trails and enhancing signage in the surrounding area to improve public safety and reduce erosion • Modifying an existing guard rail to provide safer pedestrian access for trails • Installing new stop signs and safe hit posts for traffic calming • Striping new continental crosswalks for pedestrian safety • Protecting endangered Mission Blue butterfly habitats Significant effort was put into the prep work: • Adopting and implementing a new technical specification for CIR • Core sampling of existing pavement to determine the pavement structure • Visually checking for surface indicators of potential subgrade failure • Establishing project plans, specs, and estimates for future use