CITY SPEEDING ITS SUBWAY REPAIRS

The New York City Transit Authority - with the help of three French engineers, a handful of retired track supervisors and the guidance of its acting president - has in the last month accelerated its effort to get the city's subways rolling on time.

The number of red tags on the tracks, which indicate rail problems, has been whittled down and the on-time performance of the system has climbed, according to Transit Authority figures.

The track problem was underscored last evening when a northbound IRT No. 1 train derailed as it left the station at 137th Street and Broadway, which is not a red-tag area. No injuries were reported. It was the 14th subway derailment this year.

Meanwhile Senator Alfonse M. D'Amato announced that the Urban Mass Transportation Administration, as expected, had granted $105.7 million to the Transit Authority for the rehabilitation of 11 subway stations and the replacement of defective motor- operated subway doors.

''It's always good news when these grants are finally approved and we know in fact the money is finally available,'' said Arthur G. Perfall, a spokesman for the Transit Authority.

When John D. Simpson stepped down as president of the transit system in mid-August he did so amid complaints from straphangers to the Governor of bad subway service. 'Fireman' to the Rescue

Before he left, Mr. Simpson laid the groundwork for the complete track repair program. Daniel T. Scannell, the 70-year-old acting president of the Transit Authority, is carrying out the program.

''He is a fireman who comes in so often,'' said Carol Bellamy, City Council President and board member of the parent Metropolitan Transportation Authority. ''It is clear that his No. 1, No. 2, No. 3 and No. 4 priority is red tags.''

At their peak in late July, there were 589 red tags on tracks throughout the 724-mile subway system. At each tag, motormen were required to slow their trains to 10 miles an hour. The result was one of the worst on-time records in the subway's recent history.

But by the end of last week, 367 tags had been removed and trains were more punctual throughout the system, according to Transit Authority figures.

Over the weekend, from Friday night to this morning, the Transit Authority shut down a major portion of the E and F lines. It will close the lines between 53d Street and Queens Plaza over the next two weekends, too, and other weekend shutdowns are contemplated.

''What we did was recognize that a wait of one and half to two years to bring the red-tag situation back to normal was unacceptable,'' said Mr. Scannell, as he flourished charts showing the reduction in tags. ''We sat down and organized a campaign.''

As part of that campaign, Mr. Scannell lured retired track worker supervisors back to work for four months. He won permission from the M.T.A. board to use emergency bid procedures to speed the hiring of outside contractors and the delivery of track parts - ''the big weak spot,'' he said.

''I was on the phone with Walter Williams,'' Mr. Scannell said, referring to the president of Bethlehem Steel, one of several steel companies from which the author ity buys steel parts and tracks. ''We asked them to cooperate with us and get the flow of materials to us moving faster.''

The Transit Authority expects to spend about $4 million on everything from rails to C-clamps, spikes and filler plates in the struggle to reduce red tags, he said.

For the subway rider, 589 red tags meant a summer of one late train after another.

''That number gave us 31 percent true on-time service,'' Mr. Scannell said.

''True on-time,'' he explained, is different from the transit agency's usual accounting of on-time service. In the past the authority did not include in its on-time figures scheduled work that slowed trains.

''As far as the passengers are concerned, when you look at programmed work and the red tags, we were down to 31 percent of on-time performance,'' Mr. Scannell said. ''The barometer we're using now is the barometer that tells the story for the passenger.'' Improvement in Service By the end of last week, subway service had climbed back to a 56 percent on- time performance - not good, Mr. Scannell agreed, but getting better.

''Our goal is to get the number of red tags down around 80 - our normal complement - by the end of the year,'' he said.

To help reduce the red tags, the M.T.A. has offered a 1 percent ''incentive'' raise to Transit Authority management if it can meet the accelerated goal for track repair.

And to insure that the work is done properly, Mr. Scannell has induced Jean-Marie Aubriot, the president of Societe Fran,caise d'Etudes et des Realisations de Transports Urbains - a technology exporting company specially created by the state-owned Paris subway authority - to send two engineers to evaluate the track repairs done this fall and early winter.

''The public is entitled to additional assurance,'' Mr. Scannell said. ''Their function is going to be to see that the correct repairs have been made. Our people stand to benefit by the 1 percent incentive, and this is a good, businesslike way of doing things.'' Hunt for New President

As Mr. Scannell worries about getting the tracks repaired, Governor Cuomo and the board of the Metropolitan Transportation Authority have been looking for a successor to Mr. Simpson.

Mr. Scannell said the new transit president would have to devote considerable effort to these areas:

- An extensive track renewal program for the subways.

- Modernization of the subway system's aging signal system.

- Modernization of the repair shops for buses and subways.

''It's still an uphill struggle,'' Mr. Scannell said. ''I think there's definitely been a turnaround. A number of things put in place during John Simpson's time will bear fruit. We have 1,150 new IRT cars coming, 200 new IND cars. Whoever takes over will fall heir to that.''