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Bridge Design Update
Draft EIS Marks a Milestone for East Span Project
For several years, Caltrans has been working to develop a seismic upgrade plan for the East Span of the Bay Bridge. The process has reached an important milestone with the release of the Draft Environmental Impact Statement (DEIS).
The DEIS examines the potential social, economic and environmental impacts of the East Span Project alternatives. This issue of East Span News provides information on the DEIS and the environmental review process. It also summarizes the design process and opportunities for public involvement in the project.
Providing a seismic upgrade for the Bay Bridge is a top priority of Caltrans' statewide Seismic Retrofit Program. The East Span Project is on a fast track because of the bridge's vital importance to the region. Every day, the Bay Bridge carries over 350,000 people and moves tons of goods for use throughout Northern California. The State has designated the bridge as a "lifeline" route for transporting emergency and recovery services following a disaster. Ensuring the bridge's continued function after an earthquake is critical to public safety and the Bay Area economy. Seismic upgrades on other portions of the Bay Bridge and an interim retrofit of the East Span are already underway.
The East Span Project will upgrade the bridge to withstand an earthquake of 8 magnitude on the Richter scale along the San Andreas fault, or a 7 1/4 magnitude earthquake along the Hayward fault, with minimal damage. These are considered to be maximum credible earthquakes (MCE) for the Bay Area.
To expedite the project, Caltrans is conducting design simultaneously with the environmental review process. The standard approach is to complete the environmental process and then begin detailed design. Following the standard sequential approach would extend the timeframe for completing the project. Conducting the two processes concurrently allows the project to be built sooner, thus meeting public safety needs earlier.
In using a concurrent approach, Caltrans makes certain assumptions about the outcome of the environmental review. If the assumptions are incorrect, then the project design would be adjusted to be consistent with the findings of the environmental process.
In the Draft EIS, Caltrans evaluates the range of project alternatives under consideration, including the Metropolitan Transportation Commission's recommendations. Once the environmental review is complete, Caltrans and the Federal Highway Administration (FHWA) will select a Preferred Alternative for the project. In selecting a Preferred Alternative, Caltrans and FHWA will strive for the best environmental and engineering solution for the East Span seismic upgrade.
In June 1998, the Metropolitan Transportation Commission (MTC) submitted recommendations to Caltrans on a design for a replacement bridge for the East Span. The Commission recommended a combination skyway/suspension span. The skyway concept, designed to cross shallow water and deep Bay mud, is a simple, ribbon-like pair of structures that will provide panoramic views without becoming the dominant feature in the landscape. The self-anchored suspension span, crossing deep water near Yerba Buena Island, is designed to complement the West Span. The suspension span's single tower would be embedded in rock. In its recommendation, MTC has noted that the suspension span's single-tower and self-anchored features represent important advances in bridge and seismic design, and that the span would require less maintenance than the cable-stay concept that was also under consideration.
The new span would carry eastbound and westbound traffic on separate, parallel road decks, each with five traffic lanes and two shoulders. The decks would converge into a double-deck configuration at the approach to the Yerba Buena Island tunnel. MTC also recommended a pedestrian/bicycle path and an elevated profile for the bridge. With an elevated profile, the suspension portion of the span would remain at a relatively constant grade; the skyway portion would slope gradually toward the Oakland shore. In previous actions, MTC recommended that a replacement bridge should follow an alignment north of the existing span.
The design process for the East Span Project involved an unprecedented amount of community participation, dialog and review. MTC's recommendations were reached after conducting 16 public hearings and considering thousands of comments from the public and public agencies. Over a dozen different designs were reviewed by the Commission's Bay Bridge Design Task Force and the Engineering and Design Advisory Panel (EDAP), a group of architects and engineers selected to provide expert advice on the design considerations. MTC also established a set of design guidelines to assist in the development and evaluation of the bridge design concepts.
Based on MTC's bridge design recommendations, detailed design and engineering for the project has begun. In the coming months, Caltrans will refine the design to make columns and piers more slender, develop dramatic lighting and further define other bridge components. Because the recommended concept was only taken to a 30 percent level of design to facilitate analysis and comparison with other concepts, there are still opportunities to refine the bridge design during the remaining design process. MTC and EDAP will continue to provide design oversight on the skyway structure, the transitions at Yerba Buena Island and the Oakland shore and other issues. The public will have continued opportunities to provide input to the design process through Bay Bridge Design Task Force and EDAP meetings.
MTC is responsible for regional transportation planning and financing in the Bay Area. One of MTC's initial design guidelines required that a replacement bridge should be able to accommodate possible rail service. The new span is being designed so that it does not preclude the addition of light rail trains in the future. Because the East Span Project focuses on seismic safety, rail service is not proposed as part of the current project. Currently there is no funding to provide light rail on the bridge. MTC has noted that future planning decisions on commuting through the Bay Bridge corridor should also consider increased BART, bus and ferry service and carpooling.
The National Environmental Policy Act (NEPA) requires that public agencies disclose the environmental impacts of their infrastructure projects. The East Span Project Environmental Impact Statement (EIS) considers 25 different subject areas to identify short-term impacts related to project construction and long-term impacts of the completed project. The project is statutorily exempt from California Environmental Quality Act review.
Caltrans and the Federal Highway Administration (FHWA) are the joint lead agencies for the EIS. The U.S. Coast Guard is a cooperating agency. The environmental review process also involves coordination with numerous agencies, stakeholders, interest groups and the public. The chart to the right outlines the NEPA process for the Draft EIS.
The East Span Project NEPA process began in April 1997. The Draft EIS (DEIS) was released in late September, beginning the formal public and agency comment period on the environmental document. During this time, agencies and the public can review the document and provide feedback to Caltrans. Public comments are a key part of the process.
The DEIS is a comprehensive document that provides information on many aspects of the project. The Purpose and Need section outlines the rationale for the project. The section on the alternatives explains the various approaches being considered to implement the project. Existing conditions in the project area are described, which serves as the starting point for identifying impacts. The impacts of the project alternatives are outlined for each of the environmental issues studied. Suggested actions to reduce impacts are also provided. Finally, the DEIS includes a summary of coordination and consultation with agencies, organizations and interested parties conducted during the document's preparation.
The comment period for the DEIS is 45 days. Public hearings are being held in October. Following the comment period, Caltrans will review all the information and identify a Preferred Alternative for the project in November 1998. The Final EIS (FEIS) will be published in the spring of 1999 and will focus on the Preferred Alternative. The FEIS will include responses to the comments received on the DEIS, and will report on any modifications to the project made as a result of community and agency comments. In June 1999, FHWA will file a Record of Decision (ROD) for the project in the Federal Register. The ROD serves as formal acceptance of the EIS findings and completes the NEPA process.
The Purpose and Need statement for the East Span Project was developed by Caltrans in coordination with several federal agencies. It serves to guide development and evaluation of the project alternatives.The following needs were identified for upgrading the East Span:
NEPA guidelines direct an agency to explore "all reasonable alternatives" to implement a project, including taking no action. Alternatives are developed to meet the project's Purpose and Need as closely as possible.
The East Span Project alternatives include taking no action, retrofitting the existing bridge and three replacement alternatives along specific alignments.
No-Build AlternativeThis alternative would retain the existing East Span structure. It assumes that interim retrofit work currently underway on the span has been completed. The No-Build Alternative serves primarily as a basis for comparison with the replacement alternatives.
Retrofit Existing StructureThis alternative would seismically retrofit and rehabilitate the existing East Span. This alternative would prevent multi-span collapse and catastrophic loss of life in the event of a maximum credible earthquake (mce); however, the bridge would not be usable and may not be repairable. Improvements would be made to the existing structure and the east Yerba Buena Island viaduct that links the span to the tunnel. These improvements would strengthen the bridge substructure and modify the superstructure. Two new piers would be added to the cantilever mainspan for additional support. The bridge alignment would remain the same.
Replacement Alternative N-2This alternative would construct a new bridge north of the current alignment and would dismantle the existing structure. The alignment minimizes the length of the bridge by closely following the existing span. East of the Yerba Buena Island tunnel, the bridge would transition from a double-deck viaduct to two parallel road decks. Temporary detour structures would be built on Yerba Buena Island to bypass construction where the retrofitted viaduct section connects to the new structures. The bridge would terminate along the northern edge of the existing Oakland touchdown area. The overall span length would be 11,759 feet (3,585 meters).
Replacement Alternative N-6This alternative would build a replacement bridge along a slightly curved alignment north of the N-2 alignment. This alignment maximizes views to the north of Yerba Buena Island while avoiding portions of the Bay where geologic conditions would increase construction complexity and cost. The existing span would be dismantled. The Yerba Buena Island, Oakland touchdown and detour components of this alternative are similar to Alternative N-2. The overall length of the span would be 11,877 feet (3,620 meters). This is the alignment recommended by MTC.
Replacement Alternative S-4
This alternative would construct a replacement bridge along an alignment south of the existing East Span and would dismantle the existing structure. The alignment avoids impacts to the existing East Bay Municipal Utility District sewer outfall in the Bay. The bridge transition and detour structures at Yerba Buena Island are similar to the other replacement alternatives. The span would touch down in Oakland south of the existing span. Overall span length would be 11,780 feet (3,550 meters). The suspension and cable-stayed spans considered by MTC might not be feasible with this alignment, due to space constraints near the island.
In developing the replacement alternatives, various alignments and structure types were evaluated. A number of these were subsequently withdrawn from further consideration because of various factors. These include structural, operational or safety concerns, environmental impacts or input from local cities, agencies, community groups and the public. Alternatives that were evaluated and withdrawn are discussed in the DEIS.
The retrofit and replacement alternatives would affect the existing East Span structure, which is eligible for listing on the National Register of Historic Places. Mitigation for impacts to the existing bridge includes photo and written documentation, possible relocation and reuse of bridge sections and development of exhibits, videotapes and publications to help the public understand the structure's engineering and historic significance. Caltrans is working with local historic preservationists to develop appropriate mitigation.
The replacement alternatives would not require the removal of any historic structures on the Oakland Touchdown area or military structures on Yerba Buena Island, such as the Nimitz House and the Torpedo Building. Some of the replacement alternatives could have indirect effects such as casting shadows on or affecting views from these historic buildings. Mitigation will include documentation of affected structures.
Noise and Vibration
The retrofit alternative would produce no change from existing noise levels. Under the replacement alternatives, noise levels from normal traffic on the bridge would generally be lower than existing levels. This would be due to the use of different construction materials and the elimination of reflected sound from the double-deck structure.
The replacement alternatives would reduce overall noise from current levels, but noise-sensitive receptors such as the Coast Guard barracks and historic houses on Yerba Buena Island would continue to experience noise levels exceeding FHWA acceptability criteria. The most reliable noise reduction method would be placing sound barriers along the bridge. Because this would block drivers' views, other approaches will be considered. Development of final noise mitigation measures will consider cost and effectiveness, appearance, preservation of views, safety and space restrictions.
Vibration levels for the retrofit and build alternatives would not be noticeable at distances greater than 10 feet from bridge support columns, and would therefore present no impact to sensitive receptors, such as the film studios on Treasure Island or historic buildings on Yerba Buena Island.
Construction activity for any of the replacement alternatives would result in temporary noise impacts to nearby residents on Yerba Buena Island. Limiting certain construction activity to daylight hours and the use of sound-dampening materials during pile driving are being considered.
Socio-Economics and Land Use
The retrofit and replacement alternatives would provide a beneficial impact on employment by generating jobs. None of the alternatives would have long-term effects on community services such as police and fire services and schools.
In general, the retrofit and replacement alternatives would have few negative effects on existing land uses. Land use at the Oakland touchdown area is guided by plans and policies of the City of Oakland, the Port of Oakland, the Bay Conservation and Development Commission and other agencies. Alternatives N-2 and N-6 would require one-half acre of designated "Resource Conservation Area" land. Plans to replace this area will be coordinated with the appropriate agencies. Alternative S-4 could affect the East Bay Municipal Utilities District dechlorination facility. Mitigation would entail possible modification of the alignment or relocation of the affected facilities. The Port of Oakland's planned development and expansion would be impeded by Alternative S-4, which would be mitigated by Caltrans working with the Port.
A "gateway" park at the Oakland touchdown is currently being envisioned by the East Bay Regional Park District and other interested agencies. Caltrans is working closely with the park development team to coordinate the East Span Project with the park's design.As part of the Base Closure and Reuse process, the U.S. Navy and City and County of San Francisco are currently conducting an environmental review for future reuse and development of Yerba Buena Island and Treasure Island. Bridge footings and columns for Alternatives N-2 and N-6 could restrict future redevelopment potential on the eastern end of Yerba Buena Island. Caltrans will coordinate with San Francisco to minimize impacts of the alternative ultimately selected for the project. Dismantling the existing bridge under all replacement alternatives would create additional area for island redevelopment.
The retrofit alternative would not affect existing land uses or conflict with reuse plans on Yerba Buena Island or the Oakland shore.
Construction for the retrofit and replacement alternatives will take into account possible effects on sensitive species. These include chinook salmon, steelhead trout, green sturgeon and longfin smelt, American peregrine falcons, double-crested cormorants, California least terns and harbor seals.
The retrofit and replacement alternatives would have minimal long-term effects on natural resources. Alternatives N-2 and N-6 would affect tidal mudflats and submerged eelgrass beds where birds forage and fish breed in the Oakland touchdown area. A small, isolated wetland would also be removed under the northern replacement alternatives.
The most effective mitigation approaches to offset both construction and long-term impacts are being developed in coordination with resource agencies including the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service and the California Department of Fish and Game. Mitigation may include limiting activity during bird nesting periods, replanting eelgrass and installing silt curtains during dredging.
The retrofit alternative would result in no long-term impacts to roadways or traffic circulation patterns. Two new bridge piers under the cantilever span with the retrofit alternative would have limited impacts on marine traffic. This alternative does not include a pedestrian/bicycle path.
Under the replacement alternatives, effects on existing traffic circulation on Yerba Buena Island would be minor: changes to the steep curve on Macalla Road, the loss of several informal parking spaces and a re-aligned entrance to the Coast Guard Station. The replacement alternatives would have no long-term effects on marine traffic or parking at the island or the Oakland touchdown. These alternatives would provide a new path for bicycles and pedestrians between the Oakland shore and Yerba Buena Island as an extension of the regional Bay Trail. The replacement alternatives would include shoulders on the span, which would improve traffic flow by allowing the removal of accidents and stalls from the traffic lanes.
Construction activity for the retrofit and replacement alternatives would result in some traffic disruption to Interstate-80 in off-peak periods as well as closures, detours and delays at highway ramps and various local streets on the island and in the industrial area at the Oakland touchdown. Project work would also require temporary partial marine channel closures. Mitigation includes construction traffic restrictions, signage and warning systems. In addition, a public information program will be implemented to inform the public of construction activities.
The Metropolitan Transportation Commission's recommendation that a pedestrian/bicycle path be included on a replacement bridge is proof that the public process works and that community participation can be a major factor in Bay Area policy decisions. In June, MTC recommended constructing a 15.5-foot-wide path on the southern side of the new eastbound span, raised one foot above the roadway deck. A pedestrian/bicycle path adds an exciting new dimension to the East Span Project.
The consensus reached by bicycle interests and participating agencies was accomplished through a major cooperative effort. Over the past year, Caltrans has met regularly with the Pedestrian/Bicycle Path Advisory Committee for the East Span Project. The group consists of representatives for bicycle, pedestrian, public access and disabled interests throughout the Bay Area. The meetings were used to explore options and develop workable concepts for a public access pathway. The advisory group presented its ideas on path location, multi-use considerations, lookouts, access for disabled users, and noise and air quality. Caltrans shared information on design options and standards, costs, air quality, noise, wind, and access at Oakland and Yerba Buena Island.
These discussions helped the group to develop informed recommendations for a path, which were forwarded to the bridge design team. The design team provided pedestrian/bicycle path options in its 30 percent conceptual designs, which MTC reviewed to make its recommendation on a replacement bridge design.
Caltrans and MTC will continue to meet with the advisory group to refine the path design. Issues to be addressed in the near future include shared pedestrian/bicycle access on a single path and conformance with the Americans with Disabilities Act.
A pedestrian/bicycle path was included on a list of three bridge amenities that could be funded through a two-year extension of the $1 toll surcharge on state-owned bridges in the Bay Area. The surcharge was authorized by the legislature last summer to pay for a portion of the East Span Project. The path recommended by MTC would cost $50 million and would be funded by a five-month extension of the toll surcharge.
As part of the bridge design and environmental review process, Caltrans has been coordinating with various agencies, government officials and community representatives to solicit their input.
Meetings are held regularly with the Project Development Team (PDT), which serves as a technical advisory committee for the project. The PDT consists of Caltrans technical staff and representatives of local, regional, state and federal government agencies and interest groups. The meetings ensure that a full range of viewpoints are considered in the project's overall development.
Caltrans continues to conduct meetings with the City of Oakland and the City and County of San Francisco. Meetings with Oakland representatives have focused on aesthetic refinements to the replacement bridge design, particularly the skyway section. The focus of San Francisco meetings has been the replacement bridge alignments and potential land use and access impacts at Yerba Buena Island and Treasure Island. The Navy and Coast Guard have also participated in these meetings.
Regular meetings are also held with the Oakland Gateway Joint Planning Group. The group is developing concepts for a gateway park near the bridge touchdown in Oakland. It includes representatives of the Bay Conservation and Development Commission (BCDC), East Bay Regional Park District, City of Oakland, Port of Oakland, Oakland Landmarks Preservation Advisory Board, Oakland Army Base Reuse Authority, National Park Service and the Association of Bay Area Governments. The park would provide new open space and sweeping views of Oakland, the Bay and the bridge and would serve as a dramatic gateway for bridge users entering or exiting the East Bay. While the envisioned park is not part of the East Span Project, continued coordination will help to ensure the smooth integration of the bridge and park in order to provide optimal public benefits.
Meetings are also being held with resource and permitting agencies to coordinate permit applications and approvals for building the project. These agencies include the U.S. Army Corps of Engineers, U.S. Coast Guard, U. S. Navy, BCDC, inter-agency Dredged Materials Management Office, U.S. Fish and Wildlife Service, Regional Water Quality Control Board, California Department of Fish and Game and the State Office of Historic Preservation.
Developing a seismically safe bridge for the Bay Area involves the participation of many different agencies and interests. Caltrans will continue its coordination activities throughout the construction of the project to keep the effort on track and to produce an East Span that addresses the various needs of the Bay Area.
In June, Caltrans began construction work on the interim retrofit of the East Span. This project is one of six seismic upgrade projects for the Bay Bridge.
The interim retrofit covers the full eastern span from Yerba Buena Island to Oakland, including the short viaduct structure connecting the bridge to the tunnel. The interim retrofit project will protect the bridge in the event of a smaller magnitude, more probable earthquake. The interim retrofit will not protect the bridge from more serious damage that could result from a maximum credible earthquake (MCE). The project will provide increased safety until full seismic upgrade actions for the structure are completed under the East Span Project.Additional steel plates and bolts will be installed on the structure. The work will be conducted during regular bridge maintenance periods and is not expected to affect traffic flow. The interim retrofit is expected to take about 18 months.
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