PENINSULA -- Caltrain's on-time performance and ridership numbers are up, way up, in large part because of shifted schedules and sweeping changes in the way the commuter rail line is run, officials said yesterday. But would-be riders in the East Bay will have to wait until February to see if Caltrain will offer Dumbarton rail service.

So far this month, trains have run on time more than 91 percent of the time, said Caltrain chief Mike Scanlon.

San Francisco Giants fans, meantime, have helped increase Caltrain's patronage to an all-time high, Scanlon reported yesterday at the Peninsula Corridor Joint Powers Board meeting in San Jose. If the Giants keep up their winning streak, the commuter rail line could face its toughest test to date.

``The deeper they go into the playoffs, the more trouble we're going to get into,'' Scanlon said. ``Keeping those trains running on time is going to be a challenge.''

On game days, Caltrain adds trains to serve Giants fans making their way north to Pacific Bell Park. On Wednesday -- a day that made history in the major leagues with two postseason games in the same market on the same day -- the railway offered two, seven-car trains to handle an estimated 1,300 additional riders.

Ten days before, Caltrain had added 10 trains to its weekday schedule and four trains on Saturday which marked the biggest service increase for the rail line in eight years.

The changes, compounded by continuing construction along the 77-mile Caltrain corridor, has also meant an increase in the amount of time the fleet will take to reach its destinations. On average, weekday trains are taking four to eight minutes longer over the length of the run, and weekend trains can tack on nearly half an hour in travel time.

Still, the latest performance report is welcome news for Caltrain officials, who have been grappling with a less-than-stellar on-time departure record.

During a 12-month period ending in June, on-time performance plummeted 22 percentage points, with only 66 percent of trains departing their stations on time. In June, a dismal 36 percent of Caltrain trains were on time, said Caltrain spokeswoman Rita Haskin.

Scanlon attributed the tardiness to the weekend track closings, as the railroad struggles through a $900 million overhaul that includes adding new trains and electrifying the line.

Despite its problems, Caltrain continues to run packed trains during peak hours. Overall, ridership jumped nearly 14 percent last year, to 9.82 million from 8.62 million in 1998-99. Significant jumps in ridership were recorded from April until June -- baseball season.

The last time an annual patronage record was set was in 1944, when 9.54 million people rode the trains. In the past five years, ridership has jumped by 2.4 million. In June, 32,000 people a day rode Caltrain, a 15 percent increase over the same time last year.

In 1992, Caltrain offered 50 trains. Today, the fleet is up to 78. And in November, the railroad will inaugurate a three-month trial of weekend service from Gilroy. The Santa Clara Valley Transportation Authority has committed itself to pay for the trial to see whether service to the southernmost tip of the railroad is warranted on a permanent basis. Two trains will run to Gilroy on Saturdays and again on Sundays, starting on Nov. 18.

Plans to route a commuter train across the Dumbarton Bridge were once again derailed yesterday, as the Joint Powers Board put off committing Caltrain as the sole service provider.

A long-standing motion to have Caltrain operate rail service over the 92-year-old bridge was continued until February, at which point additional funds may be available to pay for the $129 million project.

The board, which represents San Francisco, San Mateo and Santa Clara counties, also hopes the latest in a 10-year series of studies on the Dumbarton Bridge railroad trestle will provide updated information on its viability.