By Sue McCraven
The road to a bright future for drivers, taxpayers and precast concrete transportation products is being paved in sunny California.
Caltrans materials engineers are particularly excited about this I-680 project, as it includes some innovative construction methods – including a strategy to use precast/prestressed concrete paving slabs to replace damaged and worn-out road surfaces. This is the largest-ever precast concrete roadway application of its kind in the United States and is expected to reduce long-term roadway maintenance costs.
Con-Fab California Corp. of Lathrop, Calif., produced 8-ft to 36-ft long precast/prestressed concrete paving (PPCP) slabs for the 13-mile-long Caltrans rehabilitation project. State and federal roadway funds were used for the $54 million project, which began in January 2011 and is scheduled for completion this spring.
Repair to the 1960s-era infrastructure includes traffic lanes, shoulders and ramps that take on more than 170,000 vehicles per day. Work takes place at night when the lanes are closed to traffic, complementing the great advantages of precast concrete of durability and strength at installation, meaning that vehicles can drive on the lanes as soon as the panels are in position.
More than seven miles and six lanes of an eight-lane freeway between San Ramon and Alamo (suburbs of Oakland and San Francisco) were retrofitted with the 8.5-in.-thick precast concrete slabs. That’s about 8,200 cu yd of precast concrete making up more than half of the project.
According to Caltrans, which began implementing its Long-Life Pavement Rehabilitation Strategies (LLPRS) program in 1998, the goal is to rebuild about 1,750 lane-miles of high-volume freeway with pavement materials designed to last more than 30 years with minimal maintenance. Durable precast concrete pavement slabs are well-suited for this mandate, as they will reduce the need for future interruptions from road repair projects and will ultimately save public resources for travelers down the road.
Sue McCraven, NPCA technical consultant and Precast Solutions editor, is a civil and environmental engineer.