In an hour-long presentation outlining major expansion projects such as the Second Avenue subway, the executive director of the Metropolitan Transportation Authority, Elliot Sander, laid out plans for a revitalized public transportation system that would improve access for commuters, open up new routes, and relieve the stress of overcrowded trains. Following up on a $29.5 billion five-year capital plan released last week, Mr. Sander used the authority’s first State of the MTA address to describe his vision for the transportation system through the year 2050.

Alongside a slide show, Mr. Sander highlighted visions for completed projects that would include a Second Avenue subway line extending under the East River and into downtown Brooklyn, a second AirTrain to La Guardia Airport, and an extension of the Long Island Railroad into Grand Central Terminal.

“We recognize that $29.5 billion is a lot of money,” Mr. Sander said. “But we have — and I am sure you would agree — no choice.”

Transportation advocates said that the presentation included many of their pet projects but that the scale of the vision will have to be focused if the MTA is to achieve any of the ambitious expansion goals.

“Many of them are good ideas, but they need some further work,” the executive director of the Permanent Citizens Advisory Committee to the MTA, William Henderson, said. “Obviously, you’re going to need to prioritize things, because not all the resources are going to be there.”