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Seismic Retrofit Program
Fact Sheet
Program Overview
There are more than 12,000 bridges in the California State Highway system, plus an additional 11,500 city and county bridges. Each bridge is inspected at least once every two years. Some bridges are inspected more frequently. The Department of Transportation's (Department) Office of Structures Maintenance does all inspections. Since the 1971 Sylmar earthquake struck the Los Angeles area, the Department has been engaged in an ongoing bridge seismic safety retrofit program. The Department's current Seismic Safety Retrofit Program was established following the 1989 Loma Prieta earthquake to identify and strengthen bridges that needed to be brought up to seismic safety standards.
The Department appointed a Seismic Advisory Board of external engineering and scientific experts to advise the department on seismic safety policies, standards and technical practices. Peer review panels of independent seismic and structural experts also are utilized to review earthquake-strengthening strategies on major, complex retrofit projects.
A review by the Department initially identified 1,039 state highway bridges in need of being retrofitted to meet seismic safety standards, called Phase 1. The Phase 1 Program consisted of mostly single-column bridges that were most vulnerable during an earthquake. Retrofitting of Phase 1 bridges was completed in May 2000 at a cost of $1.082 billion. The work was funded by state gas taxes.
After the 1994 Northridge earthquake, The Department identified another 1,155 state-owned bridges in need of being retrofitted, which is called Phase 2. The Phase 2 Program consists of mostly multi-column bridges. Funding for this $1.35 billion program will come from the two billion dollar bond (Proposition 192), which was passed in 1996. Retrofitting of Phase 2 bridges is substantially complete (1,136 or 98.4%). Because of the complexity and the wide range of stakeholders involved in few remaining projects, completion of the last three bridges of Phase 2 will occur after 2008.
When the Seismic Safety Retrofit Program was established there was a total of nine toll bridges in California, seven of which required work in the Toll Bridge Program. The Dumbarton and Antioch bridges in the Bay area do not require retrofit. Today two of the bridges (Vincent Thomas and San Diego-Coronado) have subsequently had their tolls removed. Structures that require seismic retrofitting include the San Francisco-Oakland Bay Bridge, Richmond-San Rafael, Benicia-Martinez, San Mateo-Hayward, and the Carquinez bridges all in the San Francisco Bay Area; the Vincent Thomas Bridge from San Pedro to Terminal Island in Los Angeles County and the San Diego-Coronado Bridge. Proposition 192 initially provided $650 million for toll bridge retrofit. Senate Bills (SB) 60 and 226 were passed in 1997 to provide funding for the replacement of the East Span of the San Francisco Oakland Bay Bridge (SFOBB). In 2001 Assembly Bill (AB) 1171 was passed to provide additional funding needed to complete seismic retrofit of the toll bridges and to replace the East Span of the SFOBB.
There are a total of 1,234 local bridges statewide in the Local Bridge Program. The Streets and Highways Code identifies the Department, Los Angeles County, and Santa Clara County as lead agencies for the Local Bridge Program. Lead agencies are responsible for assessing the need for seismic retrofit work on non-State public bridges. Funding comes from gas tax revenues utilizing funds through subventions from the Departments Local Assistance Program. 560 bridges (45%) have been completed.
Seismic Evaluation
Using research developed following the 1971 earthquake, the Department implemented new bridge design criteria. From 1986 to 1989, a retrofit program developed by The Department identified single-column bridges as being potentially the most vulnerable to earthquake damage. Research sponsored by The Department at the University of California, San Diego, led to a retrofit procedure that uses steel jackets to increase the strength of columns. Following the 1989 Loma Prieta earthquake in the San Francisco Bay area, The Department sponsored accelerated retrofit research primarily conducted at the University of California at Berkeley and the University of California at San Diego. More than $40 million has been spent on seismic research since the Loma Prieta quake.
The Seismic Safety Retrofit Program now involves strengthening the columns of existing bridges by encircling certain columns with a steel casing or, in a few instances, an advanced woven fiber casing. In addition to the column casing, some of the bridge footings are made bigger and given more support by placing additional pilings in the ground or by using steel tie-down rods to better anchor the footings to the ground. In a few projects bridge abutments are made larger and the existing restrainer units are made stronger because encasing the columns make them stiffer and can change the way forces are transmitted within the bridge. Many Seismic Retrofits involve "hinge seat extensions" which enlarge the size of the hinges that connect sections of bridge decks and helps prevent them from separating during severe ground movement. The design of each bridge to be retrofitted is "site specific" or based on the maximum credible earth movement expected at that location. The calculation depends on many factors, including the nearest active earthquake fault, type of geology beneath the bridge and the original bridge design.
The toll bridges are the largest and most complicated bridges in the state, consequently, the most complex seismic retrofit schemes ever undertaken. Nowhere in the world have bridges as complex as these been seismically retrofitted. Variable soils and foundations, seismic forces nearly 10 times the original design forces, aged structures, heavy traffic volumes, conflicts with utilities, air space concerns, handling of hazardous waste, and care to protect sensitive resources all contribute to the difficulty in retrofitting these structures.
Funding
The state's bridge earthquake strengthening program will involve approximately 2,200 structures, including the state's toll bridges, and will cost more than $8 billion in construction. The breakdown of the cost is as follows:
- Phase 1 Program will cost $1.082 billion.
- Phase 2 Program will cost $1.350 billion.
- Toll Bridge Program will cost $5.085 billion.
- Local Bridge Program will cost $0.898 billion
The funding for the Phase 1 Program came from gas tax revenues utilizing funds from the State Highway Operations and Protection Program (SHOPP), which are funded from the State Highway Account and Federal Trust fund.
Proposition 192, which passed March 26, 1996, with 59.9 percent of the vote, provides for $2 billion in bonds, including retrofitting seven of the state's toll bridges and more than 1,000 other structures in Phase 2 identified for strengthening after the 1994 Northridge earthquake.
The funding for the Phase 2 Program comes from two sources. Proposition 192 bonds provide $1.21 billion. An additional $0.14 billion was expended from State and Federal funds prior to the passage of proposition 192. The total budget for Phase 2 is $1.35 billion.
AB 1171 authorizes funding in the amount of $5.085 billion to retrofit the State's toll bridges. The legislation permits use of the toll surcharge for financing purposes and provides for all financing costs. The legislation also authorizes the Department to utilize up to an additional $0.448 billion of State Highway Account funds to mitigate any cost increases above the specified $4.637 billion estimated costs. The table below summarizes the AB 1171 funding.
| Budgeted | ||
|---|---|---|
| Proposition 192 | $790,000,000 | |
| Toll Bridge Seismic Retrofit Account (TBSRA) | $3,205,000,000 | |
 Regional Share - |
||
| Bay Area Surcharge Revenues |
$2,282,000,000 | |
| San Diego Coronado Toll Bridge Revenue Fund |
$33,000,000 | |
| Vincent Thomas Bridge Contribution |
$15,000,000 | |
| State's Share - |
||
| State Highway Account (SHA) |
$795,000,000 | |
| Public Transportation Account (PTA) |
$80,000,000 | |
| Federal Highway Bridge Replacement and Rehabilitation (HBRR) | $642,000,000 | |
|
||
| Subtotal | $4,637,000,000 | |
| Contingency Funds | $448,000,000 | |
|
||
| Total | $5,085,000,000 | |
Current Status
Phase 1 Program
All of the 1,039 bridges, identified requiring seismic safety retrofit work in the Phase 1 Program, are now completed. The program was completed in May of 2000. The total cost for Phase 1 is $1.082 billion.
Phase 2 Seismic Retrofit
1,136 bridges (representing 98.4%) out of a total of 1,155 planned for Phase 2 retrofit have had seismic retrofit work completed on them. The total estimated capital and support cost for Phase 2 remains at $1.35 billion. Total commitments of $1.207 billion to date utilize approximately 89 percent of the available program funds.
A total of seven Districts have completed seismic retrofit on all their bridges in the Phase 2 Program. These are Districts 2, 3, 6, 9, 10, 11 and 12.
Local Agency Bridges Seismic Retrofit
560 projects (representing 45%) out of a total of 1,234 planned for retrofit have had seismic safety retrofit work completed or do not require retrofit work.
Toll Bridge Seismic Retrofit
Five of the seven bridges (71 percent) have been completed. The total budget as outlined in AB1171 for retrofitting the Toll Bridges is $4.637 billion and also authorizes the Department to utilize up to $0.448 billion from state Highway Account funds to mitigate cost increases if needed. The current cost estimates (as of December 2003) for the Toll Program is $5.004 billion, remaining within the AB1171 authorized contingency.
A total of $2.3 billion has been expended to date for construction and support. An additional $2.241 billion has been allocated and obligated to date (encumbered). Total commitments of $4.541 billion to date utilize approximately 89 percent of the available program funds.
Work has been completed on seismic retrofitting of the following five toll bridges: Vincent Thomas, San Diego Coronado, Benicia Martinez, Carquinez and San Mateo Hayward bridges.
Retrofit work in underway on the following two bridges: Richmond-San Rafael Bridge (one contract), and the West Span of the San Francisco to Oakland Bay Bridge (six completed contracts, two contracts under construction).
Additionally, seismic safety retrofit work will be completed on the East Span of the San Francisco-Oakland Bay Bridge through a series of bridge replacement contracts.
There are a total of sixteen contracts including two for interim retrofit of the East Span. Five contracts have been completed, four contracts are under construction, three contracts are in the bidding process and four contracts are under design.