Bay Bridge

East Span Replacement

MTC Staff Recommendations to the Bay Bridge Design Task Force
June 17, 1998

Pursuant to Senate Bill 60 (Kopp), signed into law by Governor Wilson in August 1997, this memorandum presents MTC staff recommendations on the design and amenities of the new eastern span of the San Francisco-Oakland Bay Bridge and the associated extension of the $1 seismic retrofit toll surcharge in effect on the region's state-owned toll bridges. Our five recommendations -- and the requisite toll surcharge extension to pay for those with incremental cost above the baseline bridge defined in statute -- are summarized below:

1. The new eastern span should have a single-tower self-anchored steel suspension long span at Yerba Buena Island with a variable depth concrete causeway connecting the long span to the Oakland shore.

Incremental cost: $91 million
Toll surcharge extension: 9.5 months

2. The new eastern span should have a single bicycle/pedestrian path 15.5 feet wide and 1 foot above deck level on the south side of the eastbound deck.

Incremental cost: $50 million
Toll surcharge extension: 5.2 months

3. A decision on relocating or replacing the Transbay Transit Terminal should be deferred until such time as sufficient consensus has been achieved in support of relocation or replacement of the current facility and a complete financial plan has been developed for the supported option.

4. The pile caps for the piers supporting the causeway section of the new bridge should be placed above water, but with careful attention to the design.

5. The Bay Bridge Design Task Force should provide continuing design oversight of the remaining design phase for the new eastern span including, but not limited to, the following key issues: the Yerba Buena Island transition and possible replacement ramps, the design of the causeway section of the bridge, and the Oakland touchdown.

Thus, the total incremental cost associated with our bridge design and amenity recommendations is $141 million, which would require a 14.7 month extension of the toll surcharge. Since SB 60 authorizes the Bay Area Toll Authority (BATA) to extend the surcharge up to 24 months, the staff recommendations would leave a balance of 9.3 months ($89 million) in reserve for the Transbay Terminal project subject to later action by the authority.

As acknowledged in our last memo to the Task Force on June 4, the cost of the baseline bridge is now expected to be higher than when SB 60 was passed. For example, Caltrans has included additional costs in its estimate to respond to new information regarding earthquake ground motions, and is continuing to refine its estimate of the cost of other bridge elements. Caltrans also has included contingency amounts in its cost estimates prepared to date. Under the law, any actual cost increases not covered by these contingency amounts must be reported by Caltrans to the Legislature for additional funding authorization. The $89 million in reserve for future BATA action on the Transbay Terminal is not intended to be available to cover increases in the underlying cost of the new eastern span.

Bridge Design Selection

After a 30 percent design competition among four cable-stayed and suspension alternatives and intensive deliberations over the seismic performance, architectural excellence, and cost of the four alternatives, the Engineering and Design Advisory Panel (EDAP) has recommended a single-tower self-anchored steel suspension long span for the new bridge. We recommend that BATA support the result of the extensive engineering and design review process it established by endorsing EDAPs major design recommendation. The panel concluded that the suspended long span is the best design for the following reasons:

The single-tower and self-anchored features of the suspended long span represent important advances in bridge and seismic design;
The suspension span will involve less long-term maintenance cost than the cable-stayed alternative;
It features an asymmetrical design that is not only visually appealing but allows for a superior tower foundation and wider shipping channel; and
The recommended design links the new eastern span to the Bay Areas rich tradition of suspension bridges.

EDAP also recommended that the causeway section of the new bridge have a minimum span length (distance between piers) of 525 feet except near the Yerba Buena Island transition and the Oakland touchdown, in order to reduce the number of supporting piers. To accomplish these longer causeway spans, EDAP recommended that Caltrans design and bid two alternatives for the causeway section of the new bridge: a variable depth (arch-like profile) concrete deck and a constant depth (level profile) steel deck. The winning low bid would determine the construction materials to be used.

Caltrans staff informs us, however, that this parallel causeway design process would entail $13 million in added design cost and that their current estimate that the steel causeway alternative would cost $75 million more than the concrete alternative is very likely to be borne out in the bidding process. We defer to Caltrans' judgment and, accordingly, recommend that EDAP's preference for longer causeway spans be accommodated through the lower cost variable depth concrete alternative.

Caltrans estimates that the suspension design with a variable depth concrete causeway will cost $76 million more than the baseline bridge defined in SB 60, which includes an allowance for a cable-supported long span. We recommend including architectural lighting as proposed by the design team, which will increase the cost by $15 million to a total of $91 million.

Incremental cost: $91 million
Toll surcharge extension: 9.5 months

Bicycle/Pedestrian Path

EDAP recommends including a bicycle/pedestrian path on the new eastern span. The Bay Conservation and Development Commission, the Bay Area congressional delegation, and the vast majority of public commenters have supported inclusion of a path. The new Carquinez and Benicia bridges to be constructed in the next few years also will include bicycle/pedestrian paths.

It is difficult to forecast use of such a facility but, for comparison purposes, on a recent weekend day, 5,500 pedestrians and 3,400 bicyclists used the sidewalks on the Golden Gate Bridge. Some have contended that building a path only on the new eastern span makes little sense because it will not enable users to travel all the way to San Francisco. However, we expect that many bicyclists and pedestrians will use the path for recreational purposes, and the destinations of Yerba Buena Island, Treasure Island, and even the new bridge itself will attract these users.

EDAP recommended that bicycle/pedestrian access should be accommodated with a single path on the south side of the eastbound deck, with a width and height (relative to the deck) adequate to ensure the safety and comfort of path users and protect the views of motorists. Caltrans and MTC staff have concluded that a path 15.5 feet wide and 1 foot above the roadway deck will satisfy EDAPs criteria for the safety and convenience of both path users and motorists. We recommend that such a path be included at an incremental cost of $50 million.

For your information, AB 2038 (Migden) would authorize BATA to expend toll surcharge funds on a bicycle/pedestrian path on the existing west span of the Bay Bridge. The bill has passed the Legislature and is awaiting action by the Governor. Pending enactment of the bill, we make no recommendation on a west span path at this time.

2. The new eastern span should have a single bicycle/pedestrian path 15.5 feet wide and 1 foot above deck level on the south side of the eastbound deck.

Incremental cost: $50 million
Toll surcharge extension: 5.2 months

Transbay Transit Terminal

SB 60 defines the third eligible amenity for toll surcharge extension funds as the replacement or relocation of the transbay bus terminal in the City and County of San Francisco. In our staff report to the Task Force and Commission last July, we recommended that toll surcharge funds be dedicated to the relocation of the Transbay Terminal to a new facility at Howard and Beale Streets, which is three blocks away from the present site. Our recommendation was based on the following facts:

The Office of State Architect has recommended demolishing and replacing the current building;
Caltrans will need to spend at least $70 million for seismic retrofit and code upgrade improvements to the current building and associated ramp structures;
Since the existing terminal was not originally designed as a bus terminal, it would probably require tens of millions of additional dollars for a major renovation to provide transbay bus riders with the level of convenience that could be available in a new facility;
The existing building has an annual operating deficit of approximately $1 million, which must be defrayed with bridge toll revenue every year; and the existing terminal does not meet the land use and urban design objectives of the City and County of San Francisco.

Relocation or replacement of the Transbay Terminal continues to be a legitimate long-term regional objective which we support. Nonetheless, the region is not in a position to reach consensus on a new terminal due to the current stalemate between San Francisco officials -- who support relocation -- and East Bay officials, including AC Transit -- who oppose relocation. Moreover, the proposed new terminal has an estimated capital cost of $140-170 million (depending on the number of bus decks) which is not fully funded even if BATA were to commit up to $80 million in toll surcharge funds as requested by San Francisco.

We recommend deferring a decision on the Transbay Terminal until the conditions set forth in the following recommendation are met. If the Task Force and BATA approve our recommendations on bridge design and bicycle/pedestrian access, there will be up to $89 million in remaining toll surcharge funds available for the terminal project at a future date.

Other Bridge Design Issues

The fourth and fifth staff recommendations have no effect on the toll surcharge extension, but reflect important design issues for the new eastern span. The fourth recommendation comes from EDAP and concerns the design of the piers supporting the new bridge. One of the recommendations approved by the Commission last July requested that Caltrans and the design team explore the possibility of submerging the pile caps (at the base of the piers) below water to improve visual appearance. After further analysis by Caltrans and the design team, EDAP now recommends for cost, safety, and other reasons that the pile caps should be placed above water -- as is the standard practice in bridge construction -- but with careful attention to design.

The final staff recommendation arises out of a number of unresolved bridge design issues identified by EDAP, the City of Oakland, and others that warrant close scrutiny in the post-30% phase of design. Specifically, we recommend that the Task Force provide continuing oversight for the remaining bridge design phase with respect to the issues outlined in the fifth recommendation below.

4. The pile caps for the piers supporting the causeway section of the new bridge should be placed above water, but with careful attention to the design.

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Bay Bridge

East Span Replacement

MTC Staff Recommendations to the Bay Bridge Design Task Force June 17, 1998

MTC Staff Recommendations to the Bay Bridge Design Task Force
June 17, 1998