Finding a way to get pedestrians and bicyclists safely across the railroad tracks at Jennings Avenue continues to confound the Santa Rosa City Council, which has no good options to accomplish that goal.

The council learned Tuesday that it has four options for the location west of Coddingtown, ranging from no cost to nearly $3 million.

The first and cheapest option is to do nothing, in which case the Sonoma-Marin Area Rail Transit, which expects to begin rail service in 2016, will build walls to prevent people from crossing the tracks. The cost to SMART would be $140,000, but the city would pay nothing.

The next option, which the council favors, is to build an at-grade crossing with signals to help people legally cross where they have been doing so informally for years. That would cost $451,000.

The third option is to build a 25-foot-high overpass made up of two 310-foot-long ramps. Cost: $1.7 million.

And the fourth and most expensive option is to raise the rails about 10 feet and build an undercrossing beneath it. Cost: $2.9 million.

City staff members are trying to find a way to avoid the first option because pedestrians and bicyclists have for years used the unofficial crossing and the city's general plan has long envisioned formalizing that connection point.

The fourth option has been rejected as too expensive and late to pull off, since SMART's contractor is already rebuilding the rails in the area.

That leaves the at-grade crossing and overpass as the only two viable options, but each face significant challenges.

The state Public Utilities Commission regulates rail crossings and in order to win approval for one at Jennings Avenue, the city might have to close one or even two existing crossings.

If it doesn't, the city's chances of getting a new crossing approved are "negligible," said Rick Moshier, the city's director of transportation and public works.

But that means the city might need to decide which street or streets to close before it even filed its application with the PUC.

"Closing any other street is going to be hugely controversial," said Councilwoman Susan Gorin. "The politics of that is going to collide very definitely with the environmental part of it."

Because of the complexity and uncertainty of going before the PUC, Moshier first suggested conducting an environmental report that focused on the overcrossing, with the at-grade crossing as a backup.

"The only one that you can unilaterally do is the overcrossing," Moshier said.

But the council decided that it would rather focus on the cheaper option of an at-grade crossing despite the concerns about PUC approval and potential political brouhaha it would create.

The council ultimately decided to postpone a decision on the issue to get some better numbers about the cost of the environmental work required.

You can reach Staff Writer Kevin McCallum at 521-5207 or OnTwitter @citybeater