BOSTON – Amtrak’s high-speed Acela Express train got a big boost after the terrorist attacks, and seven months later, it appears to be holding.

Credit comfort, fear of flying or backed-up airport security lines. In any case, business travelers have steadily been trying Acela Express between Boston, New York and Washington.

According to the best available records from Amtrak and airline companies, the train appears to be competing neck-and-neck with the US Airways and Delta Air Lines shuttles, which still have not fully rebounded from the Sept. 11 attacks.

Acela’s initial projections of 3.9 million annual riders at full capacity still look rosy. And nobody knows how Acela Express will fare once the novelty wears off and airport lines shrink, or whether Acela will solve Amtrak’s enormous financial headaches, which it blames on decades of federal underinvestment and political pressure to run unprofitable routes.

But more travelers have been trying the 15-month-old service, which experts say gives Amtrak a window to impress them and lure them permanently away from the shuttles.

Acela ridership stood at 96,037, or 218 passengers per train, in August, the month before the attacks. It jumped to 201,176, or 340 per train, in October, according to Amtrak figures. The numbers dipped in the fall as the airlines rebounded and Reagan National Airport near Washington reopened, but they passed 200,000 again in February and last stood at 219,917, or about 300 per train.

The airlines do not release shuttle statistics, but Bureau of Transportation Statistics filings show that last December, Delta and US Airways reported 215,366 passengers on the shuttle routes, down from 330,040 in December of 2000.

Airline figures for the first three months of this year aren’t available, so a current comparison is impossible. Both airlines acknowledge that traffic remains below its pre-Sept. 11 level.

“It is a very big concern for us,” said Delta spokeswoman Peggy Estes. “We are implementing programs and looking at new ones to get our business traveler back.”