A developer proposing a “people mover” mass transit system on the West Side could face significant obstacles, as the rail link would be highly expensive and would run on the High Line’s former rail viaduct, a space the community has sought to preserve as parkland.

The plan by the Durst Organization would create a monorail-like train to connect Pennsylvania Station with the company’s proposed development on the 26-acre West Side rail yards.

“I’m concerned about the practicality of using the High Line,” Assemblyman Richard Gottfried said, as the transit system would be competing for open space on the structure. Still, Mr. Gottfried added that additional transit connecting the rail yards with Pennsylvania Station could be an advantageous development. “Eleventh Avenue is a long walk from Eighth Avenue,” he said.

The Metropolitan Transportation Authority has examined the concept of a rail link to Pennsylvania Station, finding it unfeasible, and an official involved with plans for the rail yards said the proposal would be extremely costly. The Durst Organization said it would not pay for the entire transit project, likely needing some form of assistance from the city or state, or perhaps nearby landowners.

“It’s something that we think is interesting, and worthy of consideration,” a Durst spokesman, Jordan Barowitz, said, adding that the company’s bid could be selected without the inclusion of the peoplemover.”It’snarrowenough so that the High Line can both be used as a park and it returns the High Line to its original use as a rail line.”

Durst is one of at least six companies said to be preparing bids for the rail yards site just south of the Javits Center, the largest developable parcel of land in Manhattan. Bids are due next week, and the state has not yet announced whether any portion of the proposals will be made public before a selection is made.