DRONE FOOTAGE OF UNION CITY BART: Take a flight with us and see the station and the surrounding area from the air. Click here if you’re having trouble viewing the gallery or video on your mobile device.

UNION CITY — With a BART station and plans to connect passengers to Capitol Corridor, ACE trains and a future railroad that would cross the bay along the Dumbarton corridor, Union City’s transit station was supposed to be one of the Bay Area’s major railroad hubs.

That dream may slip further from reality, though, if city and county officials vote Tuesday to divert $75 million in funds earmarked for the station to build a new, wider road instead — a move some are characterizing as an “egregious breach of voter trust.” The complex project for the 3-mile roadway is expected to cost upwards of $320 million and comes as Union City officials contemplate declaring a fiscal emergency and asking residents to raise their taxes to cover basic city services.

City officials say the new road is critical for the station — and the planned residential and office construction around it — to thrive. The city’s railroad district, which surrounds the BART station, has been a hive of development, with about 1,700 apartment units recently constructed or planned within walking distance of the station and plans for 1.2 million square feet of office space.

But with only one way in and out of the station, traffic is expected to be untenable, said Thomas Ruark, Union City’s director of public works. The new road would alleviate congestion by extending Appian Way to connect Mission Boulevard to 11th Street, providing better access to and circulation around the station, he said.

“This provides a secondary and much-needed access,” Ruark said.

From 11th Street, the new roadway would extend Appian Way across Alvarado Niles Road, traversing Old Alameda Creek before crossing into Fremont, where Paseo Padre Parkway and Decoto Road would be widened to six lanes with added bike lanes. But the new road would cross under three sets of railroad tracks, pass through a superfund site where heavy metals have a high risk of leeching into the drinking water, require construction of three new bridges over Alameda Creek and the Alameda Country Flood Control Channel, and force demolition of the Ramirez Farm, a pesticide-free vegetable farm with a roadside stand.

“There are significant risks with each segment of this project,” according to a report to the Union City City Council. “It is highly likely that the $319.9 million may not be sufficient to deliver all the segments.”

The roadway is expected to encourage more car use, increasing congestion at more than a dozen intersections, and that has some public transit advocates, environmentalists and residents scratching their heads.

“You don’t need a highway to stimulate the BART station,” said Elizabeth Ames, the chairwoman of Save Union City Hills. “Highways are kind of old-school, and we’re trying to develop transit-oriented communities.”

The proposed roadway originally was contemplated as highway as far back as 1958, according to its environmental impact report. Lack of money kept the idea on hold for decades, until 1984 when completion of the eastern approach to the Dumbarton Bridge renewed interest. Two years later, voters in Alameda County approved Measure B, a half-cent sales tax for transportation improvements, with the roadway listed as a potential project.

But since 1989, when the project was downgraded from a highway to a local road, costs have more than quadrupled — from an estimated $88 million to $320 million — with strong local opposition, inflation, skyrocketing construction costs, regulatory issues and increasing land costs all to blame, Ruark said. The project remained on the books, though, resurfacing in the early 2000s when it was last studied, before being included in 2014 as part of Measure BB, another half-cent sales tax for transportation improvements.

A lot has changed since the project was first envisioned, said Arthur Dao, executive director of the Alameda County Transportation Commission (ACTC), which oversees Measure BB funds. And the question to ACTC’s governing board is whether to fulfill a long-held promise to local residents to build the road or take into account current land-use patterns and the desire for new and improved transit services.

“The nature of the project is very expensive,” Dao sad. “So the question is, is there a cheaper alternative … and could this funding be used for a better purpose? That’s a policy question for the board.”

It’s a question that also pits the road project against other plans to upgrade the Union City BART station and develop it as a regional railway transfer hub. The county had planned to use $75 million from Measure BB funds to construct “a two-sided rail station and bus transit facility” at the station, along with improvements to “BART parking, elevators, fare gates and other passenger amenities.”

Those improvements are not part of the roadway project, acknowledged Ruark, who added that the city plans to seek other state or regional funds to complete the transit station upgrades.

To Fremont resident Flavio Poehlmann, who drives across the Dumbarton bridge nearly every day to a job in Palo Alto, it feels like a bait-and-switch. Facebook recently invested $1 million to study a potential railroad crossing along a rail bridge that runs parallel to Highway 92, and money to improve the transit station at Union City was supposed to make that rail crossing more feasible by connecting it to BART and other services.

“If you commute over the Dumbarton Bridge, you always see the damaged rail bridge that never got rebuilt,” he said. “You see it every day as you sit on the bridge in traffic, and it’s a little bit of an insult.”

The Union City City Council is expected to vote Tuesday on whether to approve the proposed roadway project or some portion of it. ACTC’s Board of Director is scheduled to vote in March to release the funds and transfer ownership of the project to Union City.