The agency also plans to consider a "hybrid" option that would end the high-speed train line in San Jose and allow passengers to switch to Caltrain for trips further north, rail officials said Tuesday.
Rail-authority officials summarized their progress on the design of the controversial system at a hearing in Palo Alto Tuesday afternoon. More than 150 people turned out for the meeting, many of them concerned and skeptical about the proposed line.
The meeting was scheduled to give the community a sneak peak at an "alternatives analysis" for the Bay Area segment of the 800-mile line. The document, which will include details about various design options for high-speed rail on the Peninsula, is currently scheduled for release March 4.
On Tuesday, Dominic Spaethling, a regional manager for the rail authority, said the agency's analysis is considering below-grade, at-grade and above-grade options for the system in the Palo Alto area. These include the popular but costly tunneling option and the locally reviled elevated-tracks option, which could involve a wall built along the Caltrain corridor.
Spaethling, who is in charge of the San Francisco-to-San Jose segment, said the width of the Caltrain right-of-way changes at different locations throughout Palo Alto. The authority's analysis is considering a range of design options to accommodate these widths, he said.
"There are spots in Palo Alto where the (right of way) is 100 feet and there are spots where it's 60 feet," Spaethling said. "We're looking at a variety of solutions that can accommodate these widths."
Tim Cobb, whose firm HNTB is performing engineering work for the Peninsula segment, said the alternatives analysis is also considering stacking train tracks in sets of two. This could entail keeping the two existing Caltrain tracks in their current alignment and building two new high-speed-rail tracks either above or below them. This appears to be a particularly viable option at areas where the right-of-ways are narrow, such as Churchill Avenue, rail officials said.
The design of the line became a hot topic in Palo Alto last year when residents learned that the system might entail a wall along the Caltrain tracks with trains running along its top. Rail officials didn't say Tuesday which of the alternatives is currently the most viable but emphasized that all remain possible.
Spaethling said the authority will also consider investigating what he called a "hybrid" model. This could entail having passengers switch from a high-speed train to Caltrain or having the high-speed trains proceed on existing Caltrain tracks at lower speeds.
These options will not be included in the new alternatives analysis, but would be considered in a later document, he said.
The authority is also planning to release a revised environmental review for the San Francisco-to-San Jose segment in March or April, Spaethling said. The authority completed the report in 2008 but had to decertify it after a Sacramento Superior Court judge ordered revisions.
Palo Alto resident Nadia Naik, co-founder of the group Californians Advocating Responsible Rail Design, encouraged attendees to review carefully both the alternatives analysis and the revised environmental report and to send comments to the authority.
She also suggested that the alternatives analysis may be premature, given that the environmental-impacts document supporting the analysis hasn't been officially approved.
"We're picking out curtains before the bank has approved the mortgage on our property," Naik said.
Earlier this week, a coalition of nonprofit groups threatened to bring a new lawsuit against the high-speed-rail project after learning that the Authority based its ridership forecasts on a model that didn't go through a peer review.
The findings were first reported by Californians Advocating Responsible Rail Design based on a Jan. 29, 2010, memo from Cambridge Systematics, the rail agency's consultant.
However, rail officials said Wednesday that the memo with information about ridership projections contained a "typographical error" that made the model seem implausible.
The information included a wrong "frequency coefficient," a technical term used in determining ridership, rail authority Deputy Director Jeffrey Barker said Wednesday.
The rail authority also acknowledged that the model used to project ridership numbers never went through a peer review.
Spaethling and Cobb are scheduled to present the alternatives analysis for the Bay Area segment of the line at the March 4 meeting of the authority Board of Directors. Rail officials are also planning to hold public meetings on the new analysis in late March and early April.