Darrell Sapp, Post-Gazette San Balachandran, of Franklin Park, makes his way down Sarah Street on the South Side, yesterday, heading for the University of Pittsburgh. He had stayed at a friend's apartment as the winter storm moved in Tuesday. Pitt canceled morning classes yesterday.

The failure of the Port Authority's $1 billion Light Rail Transit system yesterday and Tuesday night was part of a public transit meltdown that accompanied the region's deep freeze.

Buses didn't run on time, the authority's customer service phone line was mostly unreachable, and the agency's Web site operated at a crawl. Those who were able to view the site found no information about service disruptions because the agency didn't post any.

Steve Banta, authority operations manager, said ice that formed and re-formed on the 650-volt overhead electrical wires brought the 25-mile light rail system to a stop by interrupting the flow of current to the vehicles.

Officials defended the agency's performance yesterday, saying it did the best it could under extraordinary circumstances.

"This was hardly a typical Pittsburgh weather event," spokesman Bob Grove said.

Authority employees faced the same obstacles in getting to work yesterday morning as other commuters -- meaning that the customer service department was understaffed and many bus drivers were late for work.

But Mr. Grove said the inconvenience to transit patrons was minimized by the fact that many simply stayed home.

Partial service on the main line resumed at 9:45 last night, more than 26 hours after the shutdown.

The light rail trouble started around 7 p.m. Tuesday, stopping eight LRVs in their tracks and requiring personnel to pick up riders with buses and maintenance vans to get them to destinations. The LRVs had to be towed back to the South Hills Village yard by diesel-powered rail maintenance vehicles.

There was no service again during yesterday's morning and evening rush hours because of the ice-covered power lines, worsening weather that affected repair work and malfunctioning repair vehicles.

Mr. Grove said last night that the main line will resume operations in time for this morning's rush-hour. It was not clear, he said, whether the Overbrook line would be open in the morning. The Library line was expected to remain closed indefinitely.

Shuttle buses will be employed to take riders from Library to the Castle Shannon station.

Port Authority drivers unable to get to their garages yesterday morning meant extra buses weren't initially available to establish shuttle bus service in place of LRVs, thereby inconveniencing or stranding people whose work and activities were not called off because of wintry conditions.

The T provides about 26,000 rides on a typical weekday, but only a fraction of those riders turned out yesterday, alerted by the news media about the problems.

"There were very few people anywhere in the system," Mr. Grove said.

The outage was the longest in recent memory, surpassing problems with downed wires, accidents, derailments and breakdowns -- most dating to the 1980s and early 1990s, when old-fashioned streetcars shared the tracks with modern LRVs.

Attempts to restore service were hampered when one of the rail maintenance vehicles overheated and stalled in Beechview yesterday morning. It's equipped with a special "sleet cutter" to remove ice on the overhead wires.

Later, mechanical problems occurred on the second maintenance vehicle, normally used to tamp ballast and replace ties.

While the authority worked through Tuesday night to try to deice the overhead wires, "the weather overwhelmed us," Mr. Grove said. Almost as fast as the ice was removed, wires were recoated with freezing rain.

In addition to being unable to draw power, operating the LRVs under such conditions risks more serious damage.

"I'm sure people have seen electric arcs from where the pantographs [Z-shaped, roof-mounted devices that collect power] slide along the overhead wiring," Mr. Banta said. "The concern is it can burn through the wire or burn the pantograph."

Although the T was crippled, including the Downtown subway that draws more riders when weather is bad, Mr. Grove said not as many people were affected as first feared.

"Most of the station platforms were nearly empty yesterday morning, so demand was extremely light," he said. "Most people must have decided to stay home or they found another way."

Many who tried to call customer service encountered constant busy signals.

Mr. Grove said the center was understaffed and "inundated with calls" and that call-takers "worked tirelessly" to dispense information.

He said it would be impractical to put specific information about service disruptions on the authority Web site because during storms "the conditions out there change literally every 30 minutes" and because the agency operates 213 routes.

Mr. Grove said seasoned transit riders know that in storms they should try to make their way to main thoroughfares because buses often cannot negotiate untreated, hilly side streets.