Thermal expansion shears dozens of bolts used to anchor the pedestrian / bicycle path to to the San Francisco-Oakland Bay Bridge

The eastern span of the San Francisco-Oakland Bay Bridge has been under construction since 2002 with opening of the roadway scheduled for Labor Day weekend 2013. The Chronicle reports hundreds of these one inch bolts may need to be replaced.

Crews that built the railing committed what experts called a basic mistake – they welded the bolts in place firmly in their slots rather than leaving a small amount of room to accommodate a natural expansion of the bicycle path that happens in hot weather.

As a result, scores of the 1-inch-diameter bolts have been sheared off along the 1.2-mile bike path on the southern side of the span’s skyway section. All of them, along with hundreds of others that were solidly welded, will have to be inspected and possibly replaced

Although the bike path bolts are considered a minor part of the bridge’s structure, some engineers believe this new failure of what should be a “straightforward, simple thing” raises serious questions about the state’s management of this $6.3 billion project. Last March, load bearing test on three-inch diameter rods used to secure the road deck to concrete columns resulted in the failure of a third of tested fasteners. This failure is attributed to faulty parts and will cost an estimated $10 million to fix.

The bike path was a late addition to the bridge design. The 15 1/2 foot wide path begins at the IKEA parking lot in Emeryville and swoops underneath the MacArthur Maze before connecting to the bridge as a floating structure at the edge of the bridge deck. The path only runs as far as Yerba Buena Island, and will not open for use until 2015 after the current eastern span with its infamous S-curve is demolished.

H/T Chris.