Streets were shut down and Downtown buildings evacuated yesterday after a backhoe excavating in Point State Park ruptured a gas line before noon yesterday.

The sulfurous smell of the gas filled the Golden Triangle, causing workers to flee the buildings surrounding Point State Park thinking the buildings were filling with natural gas.

Outside, the sound of the gas escaping from the line sounded like a jet engine and could be heard blocks from the break.

Despite the noise, the smell and the workers fleeing with their coats over their noses, Pittsburgh Fire Chief Michael Huss said the gas levels never built up to an explosive level and no injuries were reported.

	Pam Panchak, Post-Gazette  A repair crew works near a ruptured natural gas line at Point State Park near Commonwealth Place yesterday. Click photo for larger image. Online graphic See a map of the area of yesterday's gas leak Listen in Listen to natural gas spew from the ruptured line in this audio report on the Point State Park leak

The gas line was shut off about 40 minutes after the break, workers went back to their desks and traffic resumed along the major roadways that had been blocked.

Although the gas never reached the level at which there was a danger of explosion, many workers near the break did leave their jobs. The Hilton Pittsburgh was formally evacuated right after the leak because of the proximity to the site, Chief Huss said.

Gateway Cafeteria, which is located in the basement of Gateway Center, the Pittsburgh Post-Gazette and the State Office Building were also evacuated as the smell of the mercaptan filled the buildings.

Mercaptan, which is heavier than air, has the sulfurous smell associated with natural gas. The chemical is added to the odorless natural gas during processing so that leaks will be quickly detected.

Not since 1998, when a vehicle transporting a similar smelling noxious chemical leaked it through Downtown, has the city stunk as badly as it did yesterday.

Firefighters went through eight buildings with gas meters. Chief Huss said the meters measure the lowest explosive levels of gas, registering in percentages. He said the meters never registered above zero in any of the buildings, meaning that despite the smell, the gas was never in a high enough concentration to be explosive.

The incident started at 11:40 a.m., when a worker was breaking up concrete using a ram hoe hooked to the back of a back hoe. Suddenly there was a roar as the gas started to escape. The sound did not die down until the line was shut off.

Marty Noone, who was watching the hoe operator along with other union members who have been picketing outside the park, said, "That guy came flying out of that back hoe, I'll tell ya!"

The company responsible for hitting the line was Carnegie-based Power Contracting Co., the electrical contractor, that hit the line while breaking up a sidewalk, said Chris Novak, a spokesman for the Department of Conservation and Natural Resources. Power Contracting is one of three contractors working on the first phase of the reconstruction of Point State Park.

The park plans call for electrical hookups for vendors and for lighting on the city side of the park, she said. As for the accident, Ms. Novak said, "The details are under review."

Power Contracting officials could not be reached yesterday.

Equitable Gas workers arrived just after noon and turned off two valve assemblies, isolating the 20-inch line at New Penn Avenue and Commonwealth Place so it could be repaired. It is a local distribution supply line to the Hilton and Gateway Towers apartments, which were without service during repairs, said Dave Spigelmyer, a spokesman for Equitable.

Within five hours the gas line was repaired and the service was restored.

Asked if the contractor should have been able to avoid hitting the line, Mr. Spigelmyer said, "Absolutely. There are precautions that need to be taken when people dig. Our facilities are marked.

"There has been so much construction over there, and we mark our facilities," usually with a color of paint on the sidewalk directly above.

City Public Works Director Guy Costa, who spent the early part of the incident stringing red "do not enter" tape across New Penn Avenue, said there was no reason the gas line should have been ruptured.

"They should have known it was there. We had a meeting," he said.

Mr. Costa also said it would not have helped to have a spotter on the ground near the backhoe because the piece of equipment is like a jack hammer, which breaks up the ground so no one would have seen what it was about to hit.

Mr. Spigelmyer said there was little threat of danger unless the gas got trapped and then built up.

"Explosions occur when you have gas trapped. Outdoors, gas vents to the atmosphere quickly," he said.

Health officials said the gas itself doesn't pose a health problem.

"We don't think there would be any short- or longer-term health concerns as a result of inhalation. The main concern was the danger of explosion," said Guillermo Cole, spokesman for the Allegheny County Health Department.