Sound Transit wants to pick your brain. The mass transit agency serving urban King, Snohomish and Pierce counties is asking the public to weigh in on what the agency should do with light rail, commuter trains and buses to improve traffic.

The survey, which you can take here, comes after the failure of Proposition 1 last November. That ballot measure combined Sound Transit and a roads taxing district to ask voters to pay for billions in light rail and road improvements.

Voters overwhelmingly rejected it. But Sound Transit officials and several regional leaders believe the agency can go it alone and get voters to support a mass-transit-only tax package.

The agency wants to know how it should go it alone. Hence, the survey. The survey lasts through March 9. Among the questions it asks: How ambitious should a transit package be? What are the highest priorities for service expansions, ranging from light rail to regional express bus to commuter rail? How soon should a plan be brought to voters?

Sound Transit's board will discuss the survey results in mid-March.