Transactions Newsletter

Caldecott Tunnel Study Expands Into Corridor

In response to public requests that MTC study the concept of adding a fourth bore to the Caldecott Tunnel through the East Bay hills, the Commission decided last September to conduct a year-long study of the entire Route 24 corridor, extending 13 miles from the Interstate 580 junction in Oakland to the Interstate 680 interchange in Walnut Creek.

"The advantage of this broader approach," said MTC Manager of Planning Chris Brittle, "is that it provides necessary information on the feasibility of a new tunnel bore, at the same time addressing the full range of transportation options in the corridor, including transit, carpooling, freight and local streets."

The study is proceeding in two phases. During the first, information-gathering phase, MTC staff published a discussion paper that reviews current and projected travel conditions in the Route 24 corridor. Staff also met with interested state legislators, local elected officials, other agency staffs, and business and environmental groups to obtain their views and concerns. Phase two of the study -- analyzing options -- is expected to get under way by the end of March.

Adding a fourth tunnel bore -- most likely located to the north of the existing bores -- would provide at least four lanes in each direction all day. Currently, two lanes switch direction twice a day to serve the heaviest commute traffic -- westward in the a.m., eastward in the p.m. While the proposed fourth bore would help relieve eastbound commute problems in the morning, the existing a.m. westbound capacity would not change. Unless Route 24 is widened west of the tunnel, converting a new tunnel bore for westbound commuters in the morning would simply move the existing traffic bottleneck farther west.

With Alameda and Contra Costa counties expected to add a half-million more residents and nearly a half-million more jobs by 2020, housing, economic development and environmental issues will play a major role in decisions made on travel in the entire Route 24 corridor.

Funding to improve travel times in the corridor also is a critical issue and will be examined in MTC's study. According to Caltrans' preliminary estimates, construction costs of a new tunnel bore -- the largest single potential corridor investment -- would range from approximately $104 million (two lanes) to $146 million (three lanes).

-- Marjorie Blackwell

• Clean Air 101
• Classification Catch-22
• Air Quality Glossary
  Bay Area Air Quality Timeline
• Reduction in Emissions for
  Transportation Control Measures
• MTC Prepares Blueprint for Next Century
• Caldecott Tunnel Study Expands in Corridor
• Transportation Frustration Tracks Economy