The second broken rail for Queens riders this week halted subway service midday yesterday and fueled criticism that deferred subway maintenance has resulted in a general deterioration of service.

Members of Local 100 of the Transport Workers Union said the rail that broke yesterday was tagged last October with a yellow label, which indicates a part has a serious defect and should be replaced soon. Rails labeled red require immediate replacement.

The union has said New York City Transit has cut back by half on track inspectors and repair crews in the past year. Officials respond that better maintenance equipment has streamlined operations and lessened dependence on manpower for maintenance.

“If you detect that a rail is defective it should be replaced immediately,” the chairman of the City Council’s Committee on Transportation, John Liu, said. “Six months later? That doesn’t pass any kind of sniff test.”

A spokeswoman for New York City Transit, Deirdre Parker, could not confirm that the broken rail, which caused suspension of local service on parts of the no. 7 line for more than two-and-a-half hours, had been tagged yellow.

Yesterday’s broken rail came a day after the president of New York City Transit, Lawrence Reuter, wrote an internal memo in which he outlined a strategy for dealing with riders’ loss of confidence in the system as a result of a spate of major service disruptions this year, including an April 7 fire that sent six people to the hospital and required the evacuation of 600 riders.

That evacuation was the first since the blackout of August 2003. The authority will examine the number of personnel used to clean subway cars, platforms and tracks, where debris causes fires, including a March 22 fire at the Atlantic Avenue station.

The memo was written at the behest of the chairman of the Metropolitan Transportation Authority, Peter Kalikow, to deal with a weary public, despite performance statistics that, Mr. Reuter told a council hearing last week, show subway service has improved overall.

In a reversal, transit officials have begun using 2003, the agency’s best year for performance, as the standard for evaluating service levels. Transit officials previously defended the state of the subway by highlighting the progress made since the system was near collapse 25 years ago.

A spokesman for New York City Transit said broken rails are minor, commonplace occurrences and not a sign of disrepair, adding that there have been fewer broken rails in the past year than in 2003.

New York City Transit will also begin a program – similar to those already in use by Metro-North Railroad and the Long Island Rail Road – to send e-mail messages to riders alerting them of service disruptions. News of the memo was reported yesterday in the New York Times, Newsday, and the Daily News.

On Tuesday, the morning rush hour for riders working in Queens was disrupted when the transit authority suspended V-line service, and Jamaica-bound E and F trains ran locally between Jackson Heights and Forest Hills.