Amtrak said yesterday that more passengers rode its trains in the first eight months of the current fiscal year than in any similar period in the corporation's nine-year existence.

Amtrak's trains carried almost 13.5 million passengers between Oct. 1 and May 31, about 76,000 more than during the same period of the prior fiscal year, Amtrak said. Although a 0.6 percent increase won't knock anyone's socks off, an Amtrak spokesman pointed out that the last fiscal year was a record-breaker, partly because Amtrak was a beneficiary of a lengthy United Airlines strike last spring. If the publicly funded national passenger railroad corporation could hold its passenger level even to last year's record, it would be a very good performance, the spokesman said yesterday.

Between Oct. 1 and May 31, Amtrak actually carried about 10,000 fewer passengers on trains in the area Amtrak defines as the Northeast Corridor -- primarily the Washington-New York-Boston runs. But its ridership increased 13.4 percent, or 337,000 passengers, on its short-distance routes -- those under 600 miles -- and increased 7.6 percent, or 240,000 passengers, on its long-distance routes -- everything over 600 miles.

Amtrak said its systemwide ridership dropped 4.7 percent in May, the last month for which figures are available; however, Amtrak said this May's ridership remained nearly level with last May's when the number of riders lost as a result of discontinued trains is calculated into the total.

Two trains whose ridership is picking up considerably are Amtrak's Washington-Cincinnati train -- the Shenedoah -- and the New York-New Orleans train -- the Crescent.

Advanced bookings are running high, with 53 percent of the available reserved train coach seating in Amtrak's entire system reserved for the two-week period beginning July 7, Amtrak said. Long-distance trains -- especially those in the western region -- are the most heavily booked; Amtrak's Sunset Limited running between Los Angeles and New Orleans is 98 percent booked for coach travel over the two-week period, Amtrak said.

In other Amtrak news:

Amtrak passenger trains were on time almost 70 percent of the time in April, a 26.5 percent improvement over the same month last year, but a slip from March when Amtrak trains were on time 73.3 percent of the time systemwide. Trains are considered on time if they arrive within 5 to 30 minutes of the scheduled time, depending on the distance of the route. One of the worst performances in April was turned in by the Amtrak trains running between Washington and Philadelphia; they were on time just 11.4 percent of the time.

In response to complaints about telephone busy signals, Philip Held, Amtrak's reservations director, suggested trying to place phone calls when the loads are lightest: before 8:30 a.m., between 2:30 and 5 p.m., and after 9 p.m.