Freeways Return to Normal Quickly Thanks to Design

Driving conditions quickly returned to normal on Los Angeles-area freeways Friday with the early morning opening of the Interstate 5 and 605 Freeway interchange damaged by the magnitude 6.1 earthquake. Officials credited engineering lessons learned in the destructive 1971 Sylmar quake for limiting serious damage to freeway overpasses.

Caltrans opened all lanes of the two freeways by 5 a.m. after calling in a construction contractor to shore up the interchange and permit several damaged concrete columns to be removed and replaced during the coming weeks while the freeways remain in use.

“Everything is essentially back to normal,” Caltrans Deputy District Director Robert Ramey said.

After the 1971 experience, Ramey said Caltrans refitted about 1,500 freeway overpasses in Ventura, Los Angeles and Orange counties by connecting their bridge decks and support columns with steel cables. The cables allow some expansion because of temperature changes, but they restrain the decks from large movements, he said. New overpasses were built to a design encompassing the same principle.

In the earlier quake, traffic was tied up by monumental jams on freeways and major surface streets. A bridge collapsed onto the Golden State Freeway near Roxford Street. Top levels of the giant interchange under construction northwest of Van Norman Dam also fell. An 11-mile section of the Golden State Freeway was ruptured and strewn with debris.

By contrast, Ramey said that for the most part freeway traffic this time flowed better than on a normal day, with the worst queue of motorists stretching only about a quarter mile at the detour around the damaged I-5 and 605 interchange near the epicenter of the quake.

The Caltrans official said that within about an hour of the quake, more than 1,000 highway workers in the three counties were driving the state roadways looking for damage.

For a time after a report by a maintenance supervisor, the westbound lane of the Pomona Freeway, where it crosses Highway 71 in the Pomona area, was closed. But it was reopened in a matter of hours, Ramey said, after a Caltrans bridge engineer inspected the damage.

Also, he said, several overpasses on the San Bernardino Freeway--at Garvey Avenue, Fremont Avenue, Marguerite Street and Almansor Street--were closed until they could be inspected. All but the Almansor overpass were reopened on Thursday.

He estimated that the quake caused about $350,000 damage to 10 freeway bridges, with about $300,000 of that total expected to be spent on the I-5 and 605 interchange.