On occasion, SMART train supporters have been wary of what Marin County residents had to say about the 70-mile Sonoma-Marin commuter line — with good reason.

After all, if it weren't for Marin County opponents, who managed to kill a quarter-cent sales tax in 2006, the train would be two years ahead of where it is now and that much closer to being in operation.

Nevertheless, there's wisdom in what the Marin County grand jury has to say about SMART's future. There's good advice there as well.

First, as the grand jury recommends, the SMART board needs to be realistic about the transit line's financial challenges and start developing backup plans. It's the worst kept secret that SMART is short some $155 million for building the entire system. Originally, SMART proponents projected that the sales tax would bring in $890 million over 20 years. With the downturn in the economy, that number has dropped to $845 million, but even that may be overly optimistic.

More significantly, major changes in the bond market mean SMART will be able to borrow less and will have to pay higher interest costs. SMART also planned on getting funding help from the state and federal governments. But that's looking less promising as well.

Yet the SMART board still has not developed or approved plans for how to adjust to these new realities. Instead, train officials forge ahead under the contention that the entire line will be built by 2014.

Blind commitment to dreams is an attribute in individuals but not in public agencies. The SMART board needs to begin formulating a backup plan, which will necessitate a potentially divisive discussion about building the line in phases and/or leaving out some components.

On that note, we concur with the grand jury that the first pragmatic step is to delay construction of the $91 million bicycle/pedestrian pathway until the money is available. Such a delay would be disappointing, particularly for a region that's finally putting more emphasis on the health and environmental benefits of bike-riding. But the priority should be on building the rail line first.

It's still possible that SMART will be able to secure the funding needed to meet the 2014 deadline to build the entire system. But SMART directors can no longer afford to avoid the likelihood that it won't.

The public has become accustomed to government agencies at all levels making hard choices about funding shortfalls and about cutbacks. What it's not used to is government agencies avoiding hard economic truths all together.

SMART needs to begin work on a Plan B, and it can start by publicly acknowledging that the bike path will have to wait.