Subway Tunnels, New Green Line

The Times was correct when it headlined a story “Thin Subway Walls Called Safe by MTA” (Aug. 5), but has given the incorrect impression that tunnel walls less than 12 inches thick were approved after the fact out of expediency. That’s wrong.

The goal was to build concrete tunnel walls that would be 12 inches thick as required by contract. Where that was not possible, due to the need to maintain proper tunnel alignment, walls of 10 to 12 inches were permitted. This permission was granted only after design engineers ensured the safety factor of the tunnel would not be compromised. If that thickness could not be achieved, the contractor was ordered to install, at its own expense, double-steel reinforcement in walls that would be 9 to 10 inches thick.

The process for determining how concrete tunnel walls are to be constructed begins with an engineering survey of the newly dug tunnel and the initial concrete liner. Survey data are fed into a computer, which helps determine the final liner design. The data show where walls will be thicker or thinner and by how much, where extra reinforcing steel will be needed and where re-mining will be required. Each area where walls are designed to be less than 12 inches thick is identified and then tracked by quality inspectors.

Let’s remember that the Cording panel, which exhaustively studied Metro Rail Segment 1 in 1994, concluded that tunnel walls built thinner than designed were sufficiently strong to withstand earthquakes. The Northridge earthquake proved them right. I’m confident that the Vermont tunnels, which benefited from lessons learned during construction of Segment 1, will be equally safe.

FRANKLIN E. WHITE

Chief Executive Officer, MTA

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* State Sen. Tom Hayden’s attempts to divert Los Angeles County transit funds to other county objectives should not be characterized as a raid (“MTA Is No Longer a Sacred Cow,” Aug. 3; “Legislative Life After the MTA Battle: All Gloves Off,” Opinion, Aug. 6). It is a long overdue correction. The Los Angeles rail transit plan is an expensive boondoggle that saps resources from more productive uses. The MTA convinced the electorate to tax itself on the specious claim that a rail system would decongest roads. It wouldn’t, but it will bleed the bus system, the health care system, parks and recreation, the criminal justice system and any other public program in Los Angeles County we might care to name.

Hayden’s position is a pleasant surprise. The responses provided by Gov. Pete Wilson and Mayor Richard Riordan are a major disappointment.

JAMES E. MOORE II

Associate Professor of Urban and Regional Planning, and Civil Engineering, USC

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* “Is New Green Line a Road to Nowhere?” (Aug. 12) goes a long way to explain why Los Angeles County is near bankruptcy and the laughingstock of the nation. We have now built a rapid transit system which bypasses our airport by only a mile, and we have constructed subways in ground which is so unstable that we cannot dig basements for our houses.

What sort of government leadership and blind sheep “followership” brings us to this?

JAMES E. VINT

Redondo Beach

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* Despite the recent negative headlines about the Metropolitan Transportation Authority, mass transit in Los Angeles County did take an important step forward when the Green Line became operational.

MTA now offers a transportation system that combines 46 miles of rail network and 200 MTA bus routes that team with over a dozen municipal bus operations, Metrolink and Amtrak to create a regional transportation system.

Places like MOCA and Olvera Street in Downtown L.A. are now connected to Long Beach and Redondo Beach. Disneyland will be accessible via quick shuttle service from the Norwalk Green Line station. Attractions like the Forum, Hollywood Park, the Cerritos Performing Arts Center and the best beaches in the country are now “system accessible.” Employment and educational options are now more abundant via the system.

Metrolink and Amtrak help extend travel options to surrounding counties and even other states from the system’s hub at Union Station. Even though the Green Line does not yet travel directly into LAX, a free five-minute shuttle from the closest station provides the link.

It’s easy to forget, in the midst of other problems, that the MTA is making solid progress in creating a full service mass- transit network. The Green Line is just the latest advance.

DEANE DANA

Supervisor, Fourth District

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* I just got off the Green Line . . .

Nothing could be better than being able to make it to work from Long Beach to El Segundo in less time than it takes to drive.

Thank you, MTA. Please continue to expand the lines and create new ones.

TODD WARDEN

Long Beach