Buoyed by record-breaking public-transit ridership figures, American Public Transportation Association members are warning of the increasingly dire consequences ahead for U.S. infrastructure without action on long-term federal reauthorization funding.

APTA hopes Congress will take note of the 10.7 billion transit trips taken in 2013—the highest ridership in 57 years, the group says—and of the insatiable demand for federal programs that provide funding for mass-transit projects. The Federal Transit Administration awarded a record $15.7 billion for over 2,000 grants in FY 2014, acting administrator Therese W. McMillan said at APTA's annual conference in Houston this month.

McMillan said demand for TIGER grants exceeded supply by 15 times and added that the backlog of infrastructure projects now totals some $86 billion. "The backlog is growing by $2 billion a year," she said.

Every $1 billion invested back into that infrastructure would result in 50,000 jobs, said APTA President and CEO Michael Melaniphy. He predicted that aging baby boomers and the millennials would provide increasing transit demand.

The repeated short-term funding fixes are taking a toll, officials emphasized. "The longer we wait, the more expensive [infrastructure repairs] will be," said Phillip Washington, APTA chair and general manager of Denver's Regional Transportation District. "We have been on an infrastructure vacation for three decades."

RTD is known for launching a $2.2-billion public-private partnership deal to build 33 miles of commuter rail. "I don't know if we could do it now," said Washington, noting investor uncertainty due to the lack of a long-term federal funding component for projects.

The situation is becoming so critical that U.S. Dept. of Transportation Secretary Anthony Foxx called for APTA members to work beyond their own interests. "Now is the time to see this constellation of stakeholders come together to argue for transportation," he said. "Can we rally around a common group of solutions?"