The Lorna Prieta, California, Earthquake of October 17, 1989-Highway Systems By MARK YASHINSKY PERFORMANCE OF THE BUILT ENVIRONMENT THOMAS L. HOLZER, Coordinator U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1552-B Prepared in cooperation with the National Science Foundation UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1998 DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY MARK SCHAFER, Acting Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Manuscript approved for publication, January 28,1998 Library of Congress catalog-card No. 92-32287 For sale by the U.S. Geological Survey Information Services Box 25286 Federal Center Denver, CO 80225 CONTENTS Page Page Page San Mateo-Hayward Bridge--------- 123 Damage to culverts............................... Description of bridge----------- 123 Jetty Road at Moss Landing state beach---- Bridge damage------------------ 123 Elkhorn Road culverts........................ Bridge repair and retrofit------ 124 Spanish Ranch Road culverts---------------- References........................ 124 Summit and Morrill Road culverts----------- Mora Drive Overcrossing------------ 130 Temescal Creek culvert....................... Description of bridge----------- 130 Damage to earth-retaining structures----------- Bridge damage------------------ 130 Crib wall at Highland Road in Santa Cruz Bridge testing and repair------- 131 county........................................ Bridge motion........................................... 135 Soil-nail wall at the University of Sierra Point Overhead............................ 136 California at Santa Cruz-------------------- Description of bridge....................... 136 Damage to local highway systems-------------- Bridge motion ............................... 137 References....................................... Dumbarton Bridge................................ 143 Changes to engineering practice---------------------- Description of bridge ....................... 143 References.......................................... Bridge motion............................... 146 Conclusion............................................... Hayward Bay Area Rapid Transit elevated structure- 154 Description of bridge....................... 154 Bridge motion............................... 154 San Juan Bautista Route 1561101 Separation-- 159 Description of bridge....................... 159 Bridge motion............................... 159 Route 280-6801101 Separation------------------ 161 Description of bridge ....................... 161 Bridge motion ............................... 161 Golden Gate Bridge.............................. 163 References.......................................... 164 Highway damage........................................ 165 Damage to roads.................................. 167 Damage on State Highway 17------------- 167 Lone Tree landslide on Route I----------- 168 Eastern approach to the San Francisco- Oakland Bay Bridge ..................... 170 San Francisco city streets------------------ 171 Jetty Road at Moss Landing state beach- 172 Treasure Island.............................. 173 Sand Hill Road at Interstate 280 near palo Alto ................................... 174 Morrill Road at the San Andreas fault---- 175 Damage to tunnels................................ 176 Webster and Posey Street Tube Crossings- 176 Fort Cronkite Tunnel....................... 177 Presidio Park Tunnel....................... 177 Caldecott tunnel............................. 177 Tunnel at Geary and Avenue in Sari Francisco............................. 177 Stockton Street Tunnel (between Sacramento and Bush Streets in San Francisco)--------------------------------- 177 Broadway Street Tunnel (between Mason and Hyde Streets in San Francisco)---- 177 IV THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: PERFORMANCE OF THE BUILT ENVIRONMENT HIGHWAY SYSTEMS By Mark Yashinsky, California Department of Transportation (Caltrans) ABSTRACT gram, initiation of bridge retrofit programs in other states and countries, changes to emergency response procedures, This paper summarizes the impact of the Loma Prieta improved methods of analysis, higher levels of bridge re- earthquake on highway systems. City streets, urban freeways, search funding, legislation affecting bridges, and changes to county roads, state routes, and the national highway system society's attitudes concerning bridges and earthquakes. were all affected. There was damage to bridges, roads, tun- The Loma Prieta earthquake occurred in a remote loca- nels, and other highway structures. The most serious dam- tion and was much smaller than a maximum credible event age occurred in the cities of San Francisco and Oakland, 60 for the area. However, because it interrupted a World Series miles from the fault rupture. The cost to repair and replace baseball game being played in San Francisco, it caught the highways damaged by this earthquake was $2 billion. About world's attention. Moreover, although overall damage to the half of this cost was to replace the Cypress Viaduct, a long, state highway system was minimal, there was major damage elevated double-deck expressway that had a devastating col- to some important bridges. These facts, as well as the unfor- lapse which resulted in 42 deaths and 108 injuries. tunate loss of life on two bridges, made the California De- The earthquake also resulted in some positive changes partment of Transportation (Caltrans) a target for criticism for highway systems. Research on bridges and earthquakes after the earthquake. Some felt that Caltrans was negligent began to be funded at a much higher level. Retrofit programs in allowing seismically deficient state bridges to be used by were started to upgrade the seismic performance of the the public. Should Caltrans have been aware of any bridges nation's highways. The Loma Prieta earthquake changed that couldn't withstand a large earthquake? Should Caltrans earthquake policy and engineering practice for highway de- have replaced all bridges that were seismically deficient? partments not only in California, but all over the world. These questions led Governor Deukmejian to create a Board of Inquiry to determine why the bridge damage occurred. The board spent several months holding hearings to deter- mine what Caltrans' seismic policies were before the earth- INTRODUCTION quake. On May 31, 1990, the board published its report "Competing Against Time" (Thiel, 1990). They found that The Loma Prieta earthquake occurred on the San Andreas Caltrans had been doing a good job of improving their seis- fault in the Santa Cruz Mountains of Northern California. mic design procedures for new bridges. They felt that the The earthquake caused damage to roads and bridges within major cause of the bridge damage was the low level of fund- about 100 miles of the epicenter including major damage to ing for Caltrans' seismic retrofit program. They recommended bridges in the cities of San Francisco and Oakland. On two that Caltrans increase funding for the seismic retrofit pro- bridges, this damage resulted in a tragic loss of life. On the gram, fund additional seismic research, utilize more state- Cypress Viaduct in the City of Oakland, 42 people died and of-the-art solutions to protect bridges from future earthquakes, 108 people were injured. One person died and 13 people were and open Caltrans up to external review of its seismic poli- injured on the nearby East Bay Crossing of the San Fran- cies. cisco-Oakland Bay Bridge. Approximately 100 bridges suf- The State of California has about 24,000 state and local fered some damage from the earthquake. Eleven bridges and bridges, many of which were designed before a rigorous seis- several roads were closed, resulting in traffic problems in mic design code was developed. Before the 1971 San the weeks and years following the quake. Fernando earthquake, there was minimal seismic criteria for This report is a summary of how roads and bridges were bridges. The San Fernando earthquake was the genesis of impacted by the earthquake. The main impact was damage Caltrans' education into the effects of earthquakes on bridges. to roads and bridges. However, there were other effects to One of the lessons from that earthquake was that bridge su- bridges as well. These include changes to bridge seismic perstructures could fall off hinge and abutment seats. Thus design codes, acceleration of California's bridge retrofit pro- Caltrans began the first seismic retrofit program to provide 2 HIGHWAY SYSTEMS cable restrainers and shear Table 1 .-Chronology of significant events related to the Lorna Prieta earthquake keys on existing bridges to DATE EVENT prevent them from separating 9 February 1971 6.6 magnitude San Fernando earthquake occurs (major bridge damage). at the thermal expansion joints Causes major changes to Caltrans' seismic design procedures. during earthquakes. This pro- Initiates Phase 1 retrofit program (providing restraint at hinges). 1 October 1987 6.1 magnitude Whittier Narrows earthquake occurs (minor bridge damage). gram cost $54 million and re- Initiates Phase 2 retrofit program (providing confinement for single column bents). sulted in retrofits to about 17 October 1989 7.1 magnitude Lorna Prieta earthquake occurs at 5:04 P.M. (P.S.T.). 1,265 bridges. The earthquake (12 state bridges and several highways closed ). 21 October 1989 Rescue effort ends on the Cypress Viaduct.