Here's a sexy assignment for the 2007 state legislature: Be a home wrecker. It's not as indecent as it sounds. The marriage in question deserves to be undone.

Last year, thanks to some weird, irresponsible politicking by then house transportation chair Rep. Ed Murray (D-43), the funding to extend Sound Transit's light rail and the funding to beef up roads like I-405 and the Cross-Base Highway in Pierce County were coupled.

Now a $17 billion package is on the table: Sound Transit's $9.5 billion plan to get to the Eastside and go north, and the Regional Transportation Investment District's (RTID) $7.4 billion plan to add lanes and build new highways in King, Snohomish, and Pierce counties. Murray's legislation mandated that both packages have to pass for either to pass.

The thinking was: Coupling the projects would prevent two traditionally antagonistic camps—transit supporters and road warriors—from knifing each other. By locking their fates, the legislature reasoned, both packages would have broad-based support.

Otherwise, the thinking goes, both camps would have reason to worry. Indeed, in 2001, transit supporters single-handedly killed a similar roads package, Referendum 51. And some transit supporters worry that Pierce and Snohomish County voters would balk at expanding Sound Transit—most of the light-rail money is going to King County—without RTID's roads expansion to sweeten the deal.

Essentially, Olympia has exported the brutal legislative process of compromise to the voters.

And what's happened? Rather than propping light rail up, RTID is jeopardizing the integrity of the light-rail system. Here's why: As the combined price tag rises (RTID has yet to release revised numbers for all of its projects, but the construction-inflation spikes for the Viaduct and 520 are scary harbingers), both camps are going to be pressured into scaling back. And since they're a couple now, they're each going to be expected to give stuff up.

Forget that. It's time for Sound Transit to break up with RTID. The first order of business for the new transportation chair in the state house, Rep. Judy Clibborn (D-41, Mercer Island) should be to undo Murray's bad legislation and decouple Sound Transit and RTID. (Murray bullied Sound Transit into going along with the bum deal last year by threatening to make Sound Transit's board elected.)

But Sound Transit—and light-rail expansion—has nothing to gain from this shotgun wedding. Indeed, an Elway Poll from earlier this year found Sound Transit expansion polling well above 50 percent and RTID well below.

So, as long as Olympia has passed the buck to the voters, let's let the voters do this in a sensible way. Instead of catering to powerful road builders and business interests who push legislators to make ugly compromises (business leaders threatened to campaign against Sound Transit if it wasn't linked to RTID), the legislature should give voters a chance to make a clean decision.

Let's have a stand-alone vote on light rail and a stand-alone vote on RTID. My sense is that a single Sound Transit will make out much better than one with a ball and chain.