SAN FRANCISCO (KGO) -- Plenty of riders have criticized BART over the decades, but to really understand its strengths and weaknesses, you have to ride back even further in time, to the battles that raged before the first shovels even broke ground.
"It's right here," says BART Board Member Quentin Kopp, pointing to a map of the San Francisco Peninsula.
RELATED: BART changing schedule to start morning rides an hour later
Kopp's finger traces to the route that could have taken BART straight down the Peninsula to San Jose, potentially ringing the Bay with a single integrated transit system.
He says the path, now used by Caltrain, was originally railroad land, with a built-in right of way.
So, why didn't it happen? He points to powerful business and political interests, some of whom feared the system would suck Peninsula shoppers north to San Francisco.
"That would have been the most economical way to proceed. It didn't happen, again because of the commercial pressure from the major shopping center developer in San Mateo County," says Kopp.
RELATED: Train testing along South Bay BART extension expected soon
With the Silicon Valley boom still decades away, the semi-rural Santa Clara County also pulled out of the expensive project.
And when engineers objected to tracks on the Golden Gate Bridge, the original dream of a system running from Novato all the way through San Jose, laid out in 1960's maps and planning documents, was effectively dead.
Still, noted transportation writer Ethan Elkind believes some other missed opportunities might still be salvageable.
"BART was conceived of as a way to bring professionals from the suburbs into downtown San Francisco, downtown Oakland, so they wanted a nice comfortable ride, big seats, make it sort of a commuter train."
RELATED: VTA begins field work for BART expansion in Silicon Valley
"And there were three priorities for almost every station, parking, parking, and more parking. Elkind believes the suburban-centric mindset sacrificed a huge opportunity to build high-density hubs of transit friendly housing, which many cities initially opposed."
"What needs to happen now, is those land-use restrictions that local cities have put on BART need to be relaxed, and we need to see more of that transit-oriented development. Because otherwise the system is not reaching it's potential," he says.
Though they differ on the current political will, both Kopp and Elkind believe there's one last bold move left that could re-chart BART's future for decades to come - A second tube or bridge crossing the Bay.
"If you had that you could do 24 hour service, you could serve different parts of Oakland, the East Bay and the southern part of San Francisco, where you have a lot of job growth. And that would provide huge ridership benefits."
Perhaps it would usher in a new 21st century vision, for a transit system born roughly half a century ago.
See more articles, pictures and video about BART.
In-depth: A look at what BART could have been, what it still has potential to be
BUILDING A BETTER BAY AREA