BISMARCK, N.D. (AP) - Coal trains were moving again Monday on the main Burlington Northern Santa Fe east-west line while officials cleaned up coal from a weekend derailment.

Thirty-six cars of the BNSF coal train derailed Saturday near the State Penitentiary. No one was hurt. Railroad officials say determining the cause could take as long as two weeks.

BNSF spokesman Gus Melonas said the line was open again shortly after 8 p.m. Sunday. The railroad had been rerouting traffic through Minot and Galesburg, Ill., since the derailment.

Officials had not determined Monday how much coal spilled, Melonas said. Each car can hold more than 100 tons of coal.

The cleanup crews, on call 24 hours a day, brought vehicles and side booms to pick up the railroad cars.

When they are not cleaning up a derailment, they maintain equipment for a company called DRC Services Inc., short for Disaster Relief Co.

"We've drug 'em out of rivers, out of creeks, swamps - you name it," said C.J. Ashworth, who has worked for DRC since 1986.

The crews estimate there are about 20 train wrecks per day in the United States, though they say the pace has slowed slightly.

The Burlington Northern Santa Fe Railway also hired another company, Hulcher Professional Services, to clean up the site.

"It could take about three weeks to remove debris from the area," Melonas said.

He did not have an estimate Monday on what the derailment and cleanup would cost the railroad.

Hulcher's crew included a semitrailer that looked like a restaurant on wheels. On Sunday, the chef, Randy "Pick" Pickens of Des Moines, was serving steak, baked potatoes, salad, ice cream bars, veggies, fruit and candy bars to the cleanup crews.

About 40 train crews were sitting idle in Mandan and 50 in Dilworth, Minn., waiting for the cleanup to end.

Jerry Suko, a BN trainmaster based out of Mandan, said the damage could have been worse if the train had derailed less than a mile away, in downtown Bismarck. It came close to derailing traffic on a bridge that carries Bismarck Expressway traffic.

Coal was spilled against the trestle on the Expressway Bridge near the prison, but none of the cars hit it.

"I'd say they're lucky because that one car came awful close to the pier," Ashworth said.