Despite pleas from residents in San Jose’s North Willow Glen and Gardner neighborhoods, new tracks set to serve the massive redevelopment of the city’s transit hub Diridon Station will cut through their neighborhoods, parks and even some backyards and garages.

Bracing for daily demand at Diridon Station to rival that of the San Francisco International Airport by 2040, San Jose leaders and regional transportation officials have spent the past year gathering public opinions to create a rough blueprint for an overhaul of the station.

Although the station’s redevelopment will be years in the making, leaders from the invested parties — the city of San Jose, Caltrain, Valley Transportation Authority and California High-Speed Rail — have begun making critical decisions that will impact San Jose commuters and residents for decades to come.

The San Jose City Council has unanimously decided to move ahead with plans to expand the existing rail corridor to the south of the station, which cuts through the city’s Gardner and North Willow Glen neighborhoods, rather than pursue the construction of a bridge-like structure — known as a viaduct — that would have carried some of the trains over the Interstate 280 and Highway 87 interchange and into the city’s Guadalupe-Washington and Tamien neighborhoods.

Representatives from the four partnering agencies and their consultants will now develop more detailed plans involving Diridon and the track alignments approaching the station.

According to the team’s latest research, the anticipated future rail demand would require expanding the existing corridor to the south of the station from two tracks to up to four tracks. The expansion would affect 13 residential properties and two commercial properties, diminish the size of Fuller Park in the Gardner neighborhood by at least 30 percent and run through a current portion of the San José Word of Faith Church adjacent to the park.

The tracks will also have to be expanded to the north of the station but city-owned properties will be affected rather than residential land.

Residents in the city’s in North Willow Glen and Gardner neighborhoods — who have historically born the brunt of some of the city’s largest road and rail projects — spent the last year lobbying the city to pursue the viaduct to minimize the additional destruction to their communities.

But city and regional transit officials — as well as residents in the city’s Guadalupe-Washington and Tamien neighborhoods — agreed the viaduct posed more harm for the greater community than expanding the current corridor.

“This would consequently sandwich the Gardner neighborhood between two rail corridors, and detrimentally impact the underserved Guadalupe- Washington and Tamien neighborhoods,” Mayor Sam Liccardo and four other councilmembers wrote in a memo. “Opting for a viaduct option would also divert already limited resources from quality future mitigations in the existing corridor, such as sound walls.”

The team of representatives from the four agencies found that the viaduct would spread visual and noise impacts over a larger area, pose considerable construction and maintenance challenges and cost more than twice as much than expanding the rail lines through the existing corridor.

So instead of pursuing that option further, the council has asked city staff to work with the other transportation agencies to create a committee of local residents and stakeholders who will help offer feedback and reduce negative impacts during the project developments along the existing corridor.

San Jose leaders have also vowed to make sure that safety, noise and vibration impacts in the surrounding neighborhoods, including Gregory, Gardner and North Willow Glen, do not get worse by constructing vegetation-covered sound walls along the tracks, adding rubber bearings to the tracks and redesigning walkways and landscaping in Fuller Park.

But some residents still have doubts. Harvey Darnell, vice president of the North Willow Glen Neighborhood Association, said he was concerned that the councilmembers were making promises that they won’t be around to ensure are enacted.

“This could take 10, 20, 30 years,” Darnell said. “So I’m disappointed that they didn’t keep the viaduct around the neighborhood as an option for later when they really have a better handle on where the funding would come from and they could do a much more in-depth analysis on the real impacts to the neighborhood.”

Regional leaders anticipate that by 2040 the number of people traveling through San Jose’s Diridon Station each day will jump from 17,000 to more than 100,000.

By that time, the station is expected to serve commuters on light rail, Caltrain, Amtrak, the Capitol Corridor, ACE Train, bus lines, BART and California High-Speed Rail. And adjacent to the massive transit epicenter, 20,000 employees and thousands of new residents from Mountain View-based Google will be bustling in the tech giant’s transit village.

Redeveloping Diridon Station to accommodate all that demand will be one of the largest public works projects in the city’s history — and it may take years before the final station design takes form.

So far, the agencies have made three broad decisions — expand the tracks along the current corridor, elevate the tracks and platforms at the station and from Julian to Virginia streets at least 25 feet above the ground and construct a new station that will span from Santa Clara to San Fernando streets and feature entrances in concourses on both the east and west sides of those streets.

Officials, however, are still mostly in the conceptual phase. Councilmember Dev Davis stressed during Tuesday’s council meeting that the development was far from complete and the public should have hundreds of opportunities in the coming years to offer their feedback.

“We’re not at the project level yet, we’re just talking about using the existing corridor for when Diridon does get redone,” Davis said. “There is no timeline for this project, there’s no funding for this project and in fact, there’s no project yet. We’re literally at moving legos around.”

Caltrain and VTA’s Board of Directors will authorize San Jose’s decision to drop the viaduct track option at their meetings on Thursday. The California High-Speed Rail Authority Board will vote on it on Feb. 18.