One more post on trolleys before the week is over. In the story this weekend about Philadelphia's plans to update the trolley network, there was a description of a trolley car that stopped behind a truck parked too close to its rails. This is a great disadvantage of trolleys. They are locked into tracks and any obstacle can shut down the system. This particular trolley on Girard Avenue waited close to 10 minutes before the truck's driver came back and moved the vehicle.

From 40th Street into Center City the trolleys run underground in Philadelphia, giving them a dedicated lane of travel. But most of SEPTA's trolley lines run at least partially at street level and the Route 15 runs entirely above ground. They can be victims of traffic, red lights and poorly parked cars. SEPTA is planning to start replacing its trolley fleet with new cars by 2020. The work will include infrastructure improvements to make the trolleys more efficient.

In modern light rail projects, dedicated lanes of travel are highly desired. Locally, two trolley lines that run in Delaware County have dedicated travel lanes. They run with an on-time rate at 95 percent or better. The rest of the city trolleys, which have to share the streets with automobiles, have on-time rates between 78 and 83 percent.

Most Philadelphia streets are too narrow for dedicated lanes, but there are steps SEPTA could take that could move the line along more quickly. One, which is being looked at, is stopping less often. The Route 15 trolley, which travels Girard Avenue from the Delaware River to 63rd Street, stops in some places at just about every block. SEPTA is looking at streamlining the schedule, though that itself can be tricky.

"It's an opportunity but you have to be very careful when you look at that," said Richard Burnfield, SEPTA deputy general manager. "Someone is using every stop and you have to be very sensitive to the needs of our customers and the neighborhood, who uses that stop, what is close by."

Another option to make trolleys faster and more reliable is to restrict parking along the route. Toronto trolley expert Steve Monro said this would reduce obstructions, but would require vigilance from police and parking authority.

"If you are going to change the character of the street, you have to enforce it because otherwise it doesn't work," Monro said.

SEPTA isn't contemplating that, Burnfield said, but there may be changes in traffic lights that can move trolley cars faster. The city could create a Transit Signal Priority system on streets trolleys travel to would keep a light green until the trolley has passed through.

Another possibility would be relocating stops so trolleys don't pick up passengers until they're already through lights.

"There are different things that you can look at when you're modernizing your operations," Burnfield said. "There will be different things that will work at different locations."