Check out a recent Trains article about street running. Check out Oakland where everything on the UP and the Capitol Corridor runs on the street through Jack London Square. Only occasional crunches, but many close calls involving the clueless and the rushed. Probably one of the scariest spots in Calif. to be an engineer.

A benefit of light rail compared to heavy (BART) is that you can build a starter line for light traffic with properly designed grade crossings, then upgrade as you have need and money. With 4 trains/hour each way outside of downtown Sacramento LR only rarely causes major traffic problems, but it gets messy with more or when schedules foul up so trains are too close together. Sac has grade separations now at Sunrise (built as part of initial construction) and Power Inn (added later) on the Folsom Line, with another one under construction at Watt. Also some with major streets on the South Line (built with initial construction). When Watt is done, the way will be clear (more or less, and if operating money becomes available) to run more trains including possibly some limited-stop "expresses." Shoulda seen the traffic jams last weekend when South Watt was closed 3 days to install the main girders for the bridge.