CUPERTINO (KCBS) – A cement truck crash in Cupertino closed the connecting ramp from southbound Interstate 280 and northbound Highway 85 during the Thursday morning commute.

The double-trailer big rig, hauling 80,000 pounds of dry cement, flipped over on its side as it took the ramp around 3 a.m., said Sgt. Steve Skeen of the California Highway Patrol.

The truck driver reported traveling below the speed limit when his rig overturned, Skeen said.“He said his speed was approximately 20 to 25 miles per hour. He heard a noise on the rear trailer,” he said.

KCBS’ Matt Bigler Reports:

“The rear trailer flopped over to its left side, which caused the other trailer and tractor to roll over as well.”

The CHP issued a sig-alert at 3:41 a.m. that the entire ramp was blocked. By 6 a.m., a crane had up righted one of the trailers.

Skeen did not expect the ramp to reopen until at least 10:30  a.m., revising an earlier estimate that everything would be cleared before 8 a.m.

>> Check Current KCBS Traffic Conditions

To avoid the crash, motorists can exit I-280 at Foothill Expressway and bear right onto Grant Road, then turn right onto Fremont Avenue which runs right back to Highway 85.

(Copyright 2011 by CBS San Francisco and Bay City News Service. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)