The Next L.A. / Reinventing Our Future : Building a Better Overpass

Structural engineers at UC San Diego and the defense industry are exploring ways to build the world’s first quake-resistant highway bridge, made entirely of lightweight composite materials like those used in bulletproof vests, boat hulls and the Stealth Bomber.

Last year, a $10.5 million federal grant was awarded to the landmark bridge project, which will connect the east and west campuses of UC San Diego over Interstate 5 in La Jolla. Construction will begin in three years and take about a year. When completed, the project will cost about $55 million including, research, development and construction.

Bridge Characteristics

Support: Bridge supported by series of cables connected to an A-frame pylon

Width: 60 feet

Span: 450 feet

Lanes: One 12-foot wide traffic lane in each direction, one bicycle lane in each direction

Walkway: 13-foot-wide pedestrian walkway

Pros and Cons

* A lighter bridge would be less sensitive to ground motion from earthquakes. A chunk of composite bridge deck big enough to fill a shopping cart can be held by two kindergarten-age children.

* It’s uncertain whether composites can withstand rain, heat or sun over long periods.

* Some composites are patented, which complicates Caltrans’ attempts to set generic standards.

* Composites can cost up to $150 a pound, compared with 50 cents a pound for concrete. But supporters say composites require less labor and are quicker, easier and less costlier in the long run.