The specially-equipped suburban that rolls along tracks will someday carry commuters on the SMART train, but just how far they'll be able to go is now in question.
The cost estimate is coming in at $695 million and the projected tax revenues are only $350 million, leaving a $345 million gap.
The promise to voters who approved a quarter-cent sales tax was a 70-mile line between Larkspur and Cloverdale, but now the board has to consider shrinking it to between San Rafael and Santa Rosa.
"If we build a 40-mile system between Santa Rosa and San Rafael, we would be capturing about 60 percent of the entire ridership of the entire project," says SMART spokesman Chris Coursey.
SMART will use tracks from the former Northwestern Pacific rail line. First laid down in the 1880's, they haven't been used routinely since 1958.
Planners hope the commuter train will relieve congestion on Highway 101through Sonoma and Marin, where the only transit option now is a bus.
"We need to focus on the excitement because this is an incredible project that's going to move these two counties into the 21st century," says SMART board chair Deborah Fudge.
Santa Rosa resident Kendrick Rustad takes transit to San Francisco.
"It's no good to get to San Rafael because it's going to be a bottleneck in San Rafael, not only is the traffic a bottleneck in San Rafael, you're going to have people bottlenecked in San Rafael. It doesn't make sense to me," say Rustad.
Santa Rosa Junior College student John Ohmer is studying SMART in his political science class.
"It's kind of hard on the economy right now. It's understandable, but other than that, if they could just build this part and then work on it on a future date, it would be pretty good, I think it would be a good idea," says Ohmer.
There will be a public workshop on Saturday to go over options for how to get the most out of the available funding.