SEPTA general manager Joseph M. Casey will step down on Sept. 30, after seven years in the position and 34 years with SEPTA.

The leading candidate to replace Casey, an accountant, is deputy general manager Jeffrey D. Knueppel, a professional engineer in charge of rebuilding much of SEPTA's infrastructure.

SEPTA's board of directors is expected to name Casey's replacement next month.

Casey's tenure was marked by increasing ridership, improved state funding, new trains and buses, and national recognition: In 2012, SEPTA was named the best large transit system in North America by the American Public Transportation Association, and this year, SEPTA placed 33d in Forbes magazine's list of the nation's 500 best employers.

And SEPTA's Regional Rail system is one of only three railroads in the nation expected to meet the federal year-end deadline for installing positive train control to prevent derailments and collisions.

One of the dark days of Casey's tenure came in 2008, when SEPTA was overwhelmed by the masses who turned out to celebrate the Phillies' World Series victory.

Another negative has been SEPTA's continuing failure to to implement its electronic "smart card" fare system to replace tokens and tickets. The SEPTA Key system is years behind schedule, with little explanation.

Casey's final challenge as general manager will be moving the crowds expected for Pope Francis' visit to Philadelphia on Sept. 26 and 27.

In an interview, Casey, 59, said the pinnacle of his tenure was the increase in state funding for transit approved by the legislature and then-Gov. Tom Corbett in 2013.

The funding was narrowly approved after years of lobbying by transit officials and supporters around the state.

"It took years and years for us to get that dedicated funding, and it really set us on a great path for the future, as far as rebuilding our system," Casey said.

Casey also pointed to improved customer service and employee morale. He said the public perception of SEPTA has improved, driven by better safety, cleanliness, and civility.

A planned expansion of rail service to King of Prussia, if funded, will reverse decades of retrenchment and signal a brighter SEPTA future. That also will include new vehicles, more frequent rail service, a rehabbed City Hall subway concourse, and the long-awaited smart-card system, he said.

"I would have liked to have had that done," Casey said of the electronic fare system. "We're close. . . . It's a work in progress, obviously. It's one of those things you need to get right, and before we roll it out, we want to make sure it's right."

Matthew Mitchell, vice president of the Delaware Valley Association of Rail Passengers, praised Casey for bringing financial stability and improved customer service to SEPTA.

"The key to the whole of it has been the administrative and staffing decisions that he has made," Mitchell said. "He has not been a big noisy CEO, he has been a team leader."

Mitchell criticized "recent slippages" at SEPTA, citing declining on-time train performance and railcar shortages, as well as the long-delayed smart-card fare system.

Casey, who is paid $273,000 a year, said he expects to remain on the SEPTA payroll as a consultant until March, and will continue as chair of the transportation committee planning for next year's Democratic National Convention in Philadelphia.

In retirement, Casey, who lives in Folsom, said he and his wife will remain active in Bereaved Parents of the USA, a national self-help group for people struggling to rebuild their lives after the death of a child, grandchild or sibling.

Casey's 24-year-old son, Sean, died in a motorcycle accident in 2010.

SEPTA board chairman Pasquale T. "Pat" Deon praised Casey, in a statement, for leading SEPTA "through challenging times, while consistently improving SEPTA's performance, customer service and overall public perception. His leadership and expertise have been keys to moving SEPTA forward."

Casey joined SEPTA in 1982 from Conrail. Before being appointed general manager, Casey spent six years as SEPTA's chief financial officer and treasurer.