IF YOU'RE riding SEPTA's Regional Rail, here's hoping you're light and limber - and prepared to make a small leap to the platform at your stop. Disgruntled riders of the Trenton line have told us that their commute regularly involves minor acrobatics.

Here's what's going on: Most station platforms are old and aren't level with SEPTA's new trains. To deal with this, SEPTA installed boxes called "step-ups" to the platforms so passengers can step right off the train without a big drop.

But the box system doesn't always work. Sometimes, several Trenton line riders told us, the train doesn't line up perfectly with the step-ups. In those cases, the only way off the train is to jump. If you're lucky (or if you ask), a conductor will help you take the deep step down.

Andrea Werbock, who has been getting off at the Torresdale station for about 20 years now, said it doesn't happen every day, but it has been happening on-and-off forever.

"It doesn't make sense why they would let this go on for years," she said.

She and other Trenton-line riders we spoke with said that they've complained to SEPTA but that it feels like the agency doesn't care. Or just blames it on Amtrak.

"They never 'fess up," said one woman whose home station is Holmesburg Junction.

Last week we rode the train with Werbock and her commuter pals to see if we could experience The Drop for ourselves (though we'll note that we have felt it at the Bryn Mawr station on the Paoli/Thorndale line in the past). The rush-hour train we were waiting for was canceled and we had to board the next one.

"You sure you want to do this?" Werbock asked us. "It's not going to be pleasant." (We probably should have told her that we smelled water bottles full of urine for this column last week.)

As riders packed onto the train, we spoke with a woman named Sandy, who said she's well-versed in The Drop. When it's there, she gets off the train backward to avoid getting hurt. There were others who shared her frustration.

We finally made it to Torresdale, but after all that, the train did just fine and lined up with boxes. No drop that day.

But SEPTA knows it's a problem. Last September, a SEPTA spokeswoman said the agency would install more step-ups on the Torresdale-station platforms to make lining the trains up with the boxes easier. She said it'd take a few weeks.

Come spring, nothing has changed. What gives?

STEP-UP HOLDUP: The reason trains don't always line up with the step-ups, according to SEPTA's chief engineer Jeffrey Knueppel, is that SEPTA started using its new Silverliner trains, which have doors in different locations from the older trains. The existing step-ups are lined up to fit with the older trains, which still make up about two-thirds of SEPTA's fleet. So SEPTA needed to add more.

Knueppel gave us a full debriefing on the roughly $4 million project to build and install new step-ups.

He said that SEPTA had finished installing them on all the stations on its own territory but that when it came to the stations on Amtrak territory (like Torresdale), there were several issues that caused the delay.

"We had to do things according to their rules," Knueppel said, referring to Amtrak.

He said SEPTA workers had to be trained and retrained on working at Amtrak stations and that's why it took so long to get to Torresdale.

The good news is that just this week, SEPTA finally finished installing additional step-ups at Torresdale, and it's working on the Holmesburg station next. After that are more stations on the Trenton line, as well as stations on the Paoli/Thorndale and Wilmington/Newark line.

Once the new installations are done, there should be enough step-ups on all platforms for both kinds of trains to line up.

Ideally, Knueppel said, SEPTA could rebuild all the platforms to make them level with the new trains. But the agency doesn't have the funds to do that and probably won't for a long time, he said.

Can't get answers about city services? We can help. Reach us at howl@phillynews.com, 215-854-5855 or on Twitter @phillyhowl. More columns at philly.com/cityhowl Juliana Reyes reports for It's Our Money, a joint project of the Daily News and WHYY funded by the William Penn Foundation that seeks to explain where your tax dollars go.