Whole loaf. Half loaf. No loaf.

Those are the options Sound Transit is now considering offering the voters in November. If it reads the electorate wrong, there may not be any loaf at all for a very long time.

Last week, the agency’s board decided to move ahead – very tentatively – with three alternative regional transit packages for the November ballot.

Under the whole-loaf option, voters would be asked to approve the roughly $11 billion worth of mass transit in last November’s Proposition 1. Proposition 1 failed by a large margin, but some believe its transit projects would have fared better standing alone – not lumped together with highway projects in a package deal.

Advantage of whole loaf: A lot more gets funded, including light rail to Tacoma and Snohomish County. Disadvantages: Costs more; some projects won’t be done until 2027.

There are two half-loaf options, one costing about $6.7 billion, the other $7.8 billion, depending on whether Sound Transit seeks a 0.4 or 0.5 percent sales tax increase.

Advantages: Less sticker shock, projects get finished in 12 years. Disadvantages: Less work gets done. Another round of taxes will be needed to build out the rail system to Pierce and Snohomish counties.

The South Sound does reasonably well under all these scenarios. The smaller packages wouldn’t bring light rail from Sea-Tac Airport to Tacoma – the big prize for Pierce County – but they would set the stage for it by financing critical right-of-way purchases.

The no-loaf option – postponing any package to 2009 or 2010 – is the safe alternative.

The stakes are high. Back-to-back defeats of two transit proposals would probably foreclose the possibility of a third measure for years to come. And there’s good reason to think the voters won’t be friendly to taxes this year. The region’s economy has gone soft, and gas prices are scary.

Some members of the board think the onslaught of $3.60- or $4-a-gallon gasoline will help persuade drivers to invest more in rail and buses so they can avoid the pump.

Probably not. They’re getting bitten by gas prices right now, and the promised trains wouldn’t arrive for quite some time. It’s more likely that costly gasoline will hurt the chances of any kind of tax package in November.

But the Sound Transit board doesn’t have to make the ballot decision until this summer. It has three months to guess at how much of a loaf Puget Sound electorate will swallow come November. At the moment, the voters do not seem to have a strong appetite.