A grand plan to destroy a chunk of the Interstate 280 freeway and convert the Caltrain depot and rail yard at Fourth and King streets into a neighborhood of high-rise condos, offices and retail and entertainment space will get a serious look in a $1.4 million study proposed by city planners.

The study, which is expected to take two years to complete, will look for the best way to transform the three-block-long rail yard into a new urban neighborhood before building the downtown rail extension that will bring Caltrain to the new Transbay Transit Center, the planned electrification of Caltrain and the opening of still-uncertain high-speed rail system, which would also go to the transit center.

And don’t forget the cash that that opening 20-plus acres of of train yard and 17 acres of I-280 right-of-way for development could bring to the city.

“There is potential economic value that could be unlocked by improving the neighborhood environment … value that could be harnessed to help build the short-funded infrastructure,” the city wrote in its request for proposals to do the study.

A preliminary and much-less-detailed study in 2012 of the area suggested that land freed up by moving the rail yard and converting the freeway into a surface-level boulevard at 16th Street near Mariposa Street could be sold to developers for up to $228 million, an estimate the study described as conservative.

The key is clearing the land, which planners described as “an elevated freeway, a half-mile-long rail yard and street level railroad tracks, all of which were built in a time when the area was primarily an industrial area.”

But with the rapid and continuing development of Mission Bay and South Beach, it is, with a nod to the Giants and nearby AT&T Park, a whole new ballgame.

The rail yard and freeway now divide those growing areas from Potrero Hill and other city neighborhoods and are a barrier to motorists, cyclists and pedestrians.

Whoever gets the contract for the study will be asked to look at the effects of eliminating the freeway; possible sites to relocate the train yard; cheaper, faster and less-intrusive ways of building the underground tunnels for Caltrain and the high-speed rail; and development possibilities for the site.

But buried under the high-minded calls for a “high-quality urban environment,” a “holistic approach to the area” and “the best of 21st century urbanism” is a more mundane concern. The study also has to put a price tag on the proposed changes and determine whether there’s any feasible way the city can pay for them.

The project, if it happens, could help solve plenty of San Francisco’s problems. As one of the few large pieces of semi-open land left in the city, development would help provide both temporary and permanent jobs, along with housing the city desperately needs.

“This study will be the foundation for coordinating these (transportation) infrastructure efforts with the rapidly evolving surrounding neighborhoods,” John Rahaim, the city planning director, said in a statement.

Nothing is going to happen in a hurry, since even the Caltrain electrification project, which is the furthest along, isn’t scheduled to start in 2016, with completion in 2019. Both the downtown rail extension and high-speed rail are still waiting for funding.

Proposals from companies looking to do the study will be accepted up to Feb. 28.

— John Wildermuth