Mountain View's downtown business community finds itself in a dilemma about a crucial decision on the busy Caltrain crossing at Castro Street. In a choice between two equally unpalatable options, business leaders are making a push for Mountain View officials to hit the brakes before undertaking a potentially disruptive project to close downtown's main artery to vehicle traffic.

The city's two main options call for either tunneling Castro Street under the train crossing or making it into into a dead-end for car traffic. Either option being studied by the city presents a scary proposition for the dozens of shops and restaurants lining the city's key downtown street, said Tony Siress, CEO of the Mountain View Chamber of Commerce.

"These are the golden blocks of downtown, and they would be decimated," he said. "This would close a main thoroughfare that has been here since the start of Mountain View."

The spot has long been considered a safety hazard due to the large numbers of motorists, cyclists and pedestrians who converge to cross the train tracks. At peak hours, the vehicle traffic waiting for passing trains can easily back up and spill onto surrounding streets. Those problems are only expected to worsen as Caltrain prepares to electrify the tracks and run twice as many train trips. Further compounding to these concerns, the California High Speed Rail project also will use the same train corridor for its bullet trains.

With those developments on the horizon, city officials say it will become impractical, if not also unsafe, to continue with the status quo. As far back as 2010, Mountain View officials commissioned traffic experts to study ways to construct a so-called grade separation to split Castro Street from the tracks.

In March, the City Council began discussing the options in earnest, and members zeroed in on two starkly divergent plans for further study. On the one hand, they signaled interest in an intensive $120 million project to dig Castro Street underneath the Caltrain tracks, which would require heavy construction and road closures over the course of two years and would end up altering at least three city blocks. Alternatively, they also favored studying a simpler $45 million proposal to close off Castro Street at the train tracks and upgrade other roads to handle the traffic diversion. The City Council is expected to make a decision at a special June 22 meeting.

For business leaders, either proposal would threaten the walkable promenade dotted with outdoor dining that Mountain View has cultivated over the years, Siress said. He worries that the city is creating a "rush to judgment" for the Castro Street crossing since officials are also working on a related project to upgrade the nearby transit center. Losing access at Castro Street could create a series of new unintended problems, he said, such as limiting how delivery trucks and shuttle buses can access the downtown core.

"This whole plan seems to have been done in a bubble without understanding how downtown works," he said. "It's literally mind-boggling that no one has looked at all the effects this would have."

While city officials and consultants have acknowledged either plan would bring real impacts, they say commercial activity downtown shouldn't experience a major hit. They point to traffic studies showing that drivers would easily find new ways to access downtown. Only about 15 percent of drivers come into downtown from Castro Street, they reported, whereas the majority are coming from Shoreline Boulevard and El Camino Real.

Wanting to be sensitive to the downtown merchants' concerns, city officials commissioned a $30,000 study from the Berkeley firm Strategic Economics to investigate the potential business impacts from both Castro Street options. That study, which is set to be complete by the City Council's June 22 meeting, should provide suggestions on how to minimize the business impacts and preserve the character of downtown, said Linda Forsberg, the city's transportation manager.

Nevertheless, the Chamber of Commerce and the Mountain View Central Business Association say they want to put forward their own counter-proposals to the city. They propose building a bike and pedestrian overpass but keeping the current road crossing open. If the city needs to limit car traffic, they recommend an automated sign system that would prohibit the road crossing during peak commute times.

They readily admit their proposal would need further study, but they say it is just one example of how other ideas need to be considered. City officials said they hadn't heard anything about the business groups' counter-proposal until the Voice asked for their response to it on Monday.

The business groups' counter-proposal wouldn't bring many of the improvements of a larger project, such as road improvements along Evelyn Avenue and the transit center upgrades, said Councilman Lenny Siegel. He said he wasn't convinced that businesses would actually see fewer customers. He pointed out that both options being considered would still create a new crossing for cyclists and pedestrians to access downtown.

"It doesn't help businesses to have people stuck in traffic," he said. "Downtown business is threatened by high rents and a lack of way-finding for parking, not by street closure."

But the idea of changing downtown's main gateway presents too much uncertainty for many business owners. Speaking from his cafe right across the street from the Caltrain station, Galip Vural said the city's plans could damage the unique character of downtown Mountain View as well as its success as a commercial "goldmine." As the owner of Olympus Cafe and Bakery and the restaurant Ephesus, he said he was already bracing for a hit from a temporary loss in parking due to a nearby hotel project that will occupy two city-owned lots. But if city officials also decided to cut off Castro Street — whether temporarily or permanently — he was certain that would be a fatal blow for some businesses.

"If you close Castro, I'm sure that some businesses would end up closing down," Vural said. "Closing Castro would be the worst decision the City Council could ever make."