But the 125-mph trains still could zip along on an aerial viaduct, in an underground tunnel, through an open trench or at street level, according to a report released Thursday by the California High-Speed Rail Authority.
The Authority's "preliminary alternatives analysis" identifies ways that the 48 miles of tracks between San Jose and San Francisco could be configured. It also eliminates options it deemed unfeasible due to factors such as geology, various cities' regulations, negative effects on traffic, the need to protect natural resources and more.
The overall rail line, which would stretch from Los Angeles to San Francisco, received voters' approval for $9.95 billion in funding in November 2008.
Since then, rancorous debate and considerable grass-roots activism, along with city-organized lawsuits and lobbying, have ensued. Opponents, some protesting the rail line altogether and others advocating for a plan that will not harm residents' quality of life, have questioned the state agency's processes, calculations and receptivity to public input.
But holding fast to its prior plans, the Authority states that its analysis "reconfirms that a four-track, grade-separated, shared Caltrain and High-Speed Train system is feasible and the preferred ... alternative between San Francisco and San Jose on the Peninsula."
Furthermore, it asserts the costs for building the system are consistent with prior estimates, including those found in the 2009 Business Plan, which was released in December.
The agency did state that it has heeded community wishes, however, which have been vocally expressed over the past year and a half. The report promises that berms — solid walls that would extend at least 10 feet into the air — will be sparsely used in commercial or residential areas "where they would significantly reduce connectivity and mobility or where there is strong local opposition to this type of structure."
The agency removed high berms from consideration altogether from Redwood City to San Jose, though shorter berms may be used to connect aerial and underground or at-grade portions.
The report confirmed that tunneling — an expensive method advocated by local officials as early as 2008 — has been added "for further evaluation."
Using underground tunnels is only one of six options the Authority is studying. The other five include berms; aerial viaducts, which are concrete structures supported by columns, usually 10 feet or taller; at-grade tracks that run at or near ground level; open trenches, which are below-ground-level troughs; and covered trenches/tunnels, which are partly covered troughs that allow ground-level roads or buildings to exist above the rail line.
Robert Doty, director of the Peninsula Rail Program, a partnership between Caltrain and the High-Speed Rail Authority, said the communities along the route made it very clear that they felt the berms would be "extremely intrusive." Even though the structures are technically feasible, the rail authority opted to eliminate them from further consideration.
"The tunnel option is still in place," Doty said, referring to the Palo Alto, Menlo Park and Atherton portion of the line. "All the options are in place, to be honest, from the feasibility perspective. All are available and can be done."
"We'll work with the communities and groups to pick from what's available."
The rail authority also eliminated the option of stopping the high-speed rail in San Jose, a design that some Peninsula residents have advocated at public meetings. Doty said stopping the service in San Jose would meet neither the purpose of the project nor the requirements of Proposition 1A, which specifies that the rail system should go between San Francisco and Los Angeles.
He also said the design would not meet the needs of Caltrain, which would have to absorb northbound rail passengers bound for San Francisco.
"There's no way the system we have out there today would absorb what happens if the system stopped in San Jose," Doty said.
Locally, all options other than the berm remain. But the detailed analysis showed that the rail line could affect city life in various ways.
For example, building either an aerial viaduct or an open trench crossing the Menlo Park and Palo Alto border would adversely affect San Francisquito Creek (in fact, the open trench is not considered an option for that stretch).
Some methods will be significantly costlier than others. Yet the Authority did not eliminate any option solely on cost, according to the report. Rather, it is opting to design the whole San Jose to San Francisco corridor and then estimate the costs for each segment.
The Authority warned that the most costly of alternatives may not be feasible. If every segment of the line was built with the most expensive method, the cost for the whole route could be four to five times more expensive than what has been estimated.
"Such high-cost alternatives would be impractical," the report stated.
The alternatives will now be analyzed with greater scrutiny for their potential environmental impacts and engineering feasibility. That environmental impact study is expected to be completed by December 2010.
In addition to analyzing design options, the state agency also confirmed that it is still considering whether to build a mid-Peninsula station. If so, Palo Alto, Mountain View and Redwood City are all possibilities.