The bicycle's front wheel crossed the wet trolley track and, already unstable because of an uneven road, slipped almost immediately.

Katie Monroe, then 23, fell to the left as her bike skidded right at the intersection of 11th and Reed Streets in South Philadelphia. The impact broke her jaw in three places and shattered teeth. At first, she was in such shock, there was no pain. She was even able to call a friend to help her get to a hospital.

"The pain, once it hit, was the worst pain I've ever experienced," Monroe said.

For a month, she lived on a liquid diet while her healing jaw was wired shut. But almost immediately, Monroe said, she thought about how many other bikers had damaging run-ins with trolley tracks. At the time, she was working for the Bicycle Coalition of Greater Philadelphia, and she felt she could use her situation to effect change.

"I just think that if the tracks are lying there and are falling apart and are not serving the purpose of having a trolley run on them, then we should get rid of them," Monroe said.

Last month, almost three years later, SEPTA personnel pulled those same tracks out of the ground, the latest step in a multi-year effort by Monroe and the Bicycle Coalition to make city streets safer for cyclists.

Along with being slippery when wet, grooves in trolley tracks are just wide enough to "swallow" a bike wheel, making it impossible to steer, said Randy LoBasso, a spokesman for the Bicycle Coalition. Accidents, from scraped knees to more serious injuries, are common.

"I know a lot of cyclists, and everyone I know has had an incident with trolley tracks," LoBasso said; often, accidents are not reported.

Since 2014, prompted by lobbying from Monroe and the Bicycle Coalition, SEPTA and the Philadelphia Streets Department have removed or paved over tracks at about a dozen South Philadelphia intersections. The work has focused on unused portions of the old Route 23 trolley tracks that stretch from South Philly past Reading Terminal Market. Buses replaced trolleys on the route in 1992. The Bicycle Coalition is now talking to the city and SEPTA about addressing tracks on straight portions of 11th and 12th Streets, LoBasso said. The streets get heavy bike traffic, he said, and 12th Street has a bike lane.

Paving over trolley tracks is preferred. It's cheaper and causes less disruption. The Streets Department prioritized some of the intersections ahead of its normal repaving schedule to address the bikers' concerns, said Mike Carroll, the department's acting commissioner. The work was paid for through the $21 million paving budget.

In some cases, such as when a road surface is sloped the way it is at 11th and Reed, tracks must be pulled up. Covering or removing them improves street quality, said Bob Lund, SEPTA's assistant general manager for engineering, maintenance, and construction, and SEPTA has no plans to return trolleys to the route -- though if that were to happen, old tracks would have to be removed anyway. SEPTA manages 190 trolley-track miles in Philadelphia, about 70 miles of which are unused.

Active trolley tracks can be just as risky for cyclists, LoBasso said. When on a bike, cross tracks at a 90-degree angle and, if the tracks are wet, try to avoid them entirely.

Early in September, Monroe, who lived in South Philadelphia at the time of the  accident and now lives in Fairmount, was on hand to watch workers pull up the tracks she had been injured on.

"I walked into the Acme, and I bought a dozen roses and a thing of cookies," she said, "and I brought them out to the gentlemen who were ripping up the trolley tracks."