Bay Crossings Study 1991

The 1991 Bay Crossings Study

Several times since the 1960s Bay Area transportation planners, officials, and voters have considered proposals for a toll bridge crossing the San Francisco Bay south of the existing San Francisco-Oakland Bay Bridge. These earlier proposals and studies revolved around the concept of a new auto bridge located approximately four miles south of the San Francisco-Oakland Bay Bridge.

In April 1966 the now-defunct California Toll Bridge Authority authorized a new bridge extending from India Basin in San Francisco to Alameda, Oakland, and San Leandro, and appropriated funding for study and preliminary design. This alignment was studied in 1971. The next year voters in Alameda, Marin, Contra Costa, San Francisco, Santa Clara, and San Mateo counties were given a chance to vote on this new bridge, and they rejected the proposition. It is generally assumed that voters and local officials opposed the bridge due to environmental concerns and concerns for the impact on BART transbay service, which had not yet become operational.

In 1991 the Metropolitan Transportation Commission (MTC) undertook another study of transbay travel and new transbay transportation facilities in response to State Senate Concurrent Resolution 20, presented by Sen. Quentin Kopp. SCR 20 specifically cited current and growing congestion on the San Francisco-Oakland Bay Bridge and BART as a reason for considering improvements to transbay travel.

However, rather than focusing solely on a new auto bridge, as in the past, the 1991 Bay Crossing Study (also known as the SCR-20 study) took a broader approach. In addition to studying what would happen if no new facility were built (called the baseline), it examined 11 different "build" alternatives for improving transbay travel:

1. High-Speed Ferry and Operational Upgrade
2. Southern Crossing Bridge
3. Southern Crossing tunnel
4. Interstate 380 to I-238 bridge (with BART)
5. Interstate 380 to I-238 tunnel (with BART)
6. BART SFO/OAK airport connection
7. BART Alameda to Candlestick connection
8. New BART Transbay Tube
9. Airport peoplemover connection
10. Railroad Airport connection
11. Intercity rail connection

A policy committee established by SCR 20 reduced the number of alternatives for detailed study to five: alternatives 1, 4, 6, 8, and 11. The impacts of each alternative on travel demand, growth, and environmental resources were analyzed, using a 2010 planning horizon. Preliminary estimates of capital costs of each alternative ranged from a low of approximately $900 million for Alternative 1 to a high of almost $4 billion for Alternative 6 (all costs in 1990 dollars). Some key findings from the 1991 Bay Crossing Study are:

Planned and programmed improvements at the time of the study (the baseline), including widening of the San Mateo Bridge and more frequent BART service, would provide enough capacity to accommodate transbay travel to the year 2010, but at high and increasing levels of congestion.
Alternative 4, a new midbay bridge, would carry the greatest number of trips of the five alternatives studied in detail. While peak-hour volumes on the existing San Francisco Bay Bridge would not be reduced, the duration of the peak period would be reduced by over an hour.
Construction of Alternative 4 would have significant land use impacts including displacement of homes and businesses, and destruction of wetlands.
Tunnel options have significant environmental impacts due to dredging. Bay water quality would be impacted and disposal of a very large amount of dredge spoils would have to be addressed.

The 1991 Bay Crossings Study is available at the MTC Library.

SOURCE: www.mtc.ca.gov/library/bay_crossing/bay_crossing2.htm