Though Philadelphia has been spared the tons of snow falling regularly on Boston, the arctic temperatures have played havoc with dozens of the vehicles in SEPTA's aging fleet.

Extreme weather conditions have caused 60 regional line train cars to break down, a SEPTA spokesman said. The transportation authority's entire regional fleet is made up of around 350 train cars.

In recent years, SEPTA has purchased 120 new regional train cars, but the remaining two-thirds of the fleet is becoming quickly outmoded. Some of the vehicles are from the 1970s --the ones most susceptible to extreme weather conditions, according to a spokesman.

"Some of the vehicles we have are some of the oldest in the country," said Jeff Knueppel, SEPTA's deputy general manager.

Often, snow will get into a train's motor, quickly melt, then short-circuit the engine, bringing the vehicle to a halt.

Another issue occurs when salt becomes lodged in a train car's door, rendering proper movement impossible, Knueppel said.

These types of winter headaches aren't likely to cause long-term grief for commuters since all the broken-down cars have been replaced and are now undergoing repairs. And Knueppel said SEPTA has 70 train cars stored in reserve in case others are put out of commission.

The snow crisis in Boston is likely to prompt some soul-searching at SEPTA. How would Philadelphia respond to back-to-back mega-storms?

Knueppel said the agency is now mulling that question and devising a strategy.

"We keep the equipment moving. We keep it running. In a sense, by constantly running the equipment, that plows the line, and that's very important for us," Knueppel said. "That is very, very important for us. Keeping the core of the system is really, really important for us."

Knueppel said, if a massive storm were to befall Philadelphia, he probably would have reacted much the same as Boston officials responded: bringing service back on line as fast as possible, but keeping expectations reasonable.

"There's only so many ways to get rid of ice, and it's just the logistics of getting rid of massive amounts of snow can take time," he said.

In the wake of Boston's storms, transportation officials there have sparred with the governor over how quickly service can fully return. And the general manager of that city's transportation authority announced her resignation amid the heightened tension.

To prove that Philadelphia is battle-ready for a massive snowfall, Knueppel pointed to three of SEPTA's secret weapons: a jet engine that attaches to a rail vehicle and aggressively blows away snow; a large snow-thrower the size of a front of a train; and rotating brooms affixed to trolleys to sweep away any accumulation.

The last snow nightmare SEPTA experienced was in 1996, when 30 inches of snow fell on the city. That year, the authority spent a lot of time cutting deals with farmers, private business owners and county governments for temporary land use -- since there was no place in Philadelphia to dump the snow.

When pushed about what he would have done differently had he been in charge of Boston's transit response, Knueppel pivoted to a larger point about the consequences of the warming planet.

"What I can tell you," Knueppel said, "is that climate change is really here. Whether you believe in global warming, and all those kind of things, you have to admit that our weather extremes have become more severe, whether it's the amount of heavy rainfall events, extremely hot and extremely wet summers. The Northeast, with our old infrastructure, we're vulnerable."