A light in the darkness!

Leaves me wondering if rail transit on the (up front) cheap using diesel-powered equipment - like WES, Sprinter, and now SMART - is really worth the effort. You still have to go to the expense of fixing up the physical plant for passenger service, with stations, signals, better track, etc. The cars cost and weigh more than comparable LRVs or MUs because they're custom, and have lower performance. If designed to co-operate with freight like WES and SMART, the cars are MUCH heavier than normal transit vehicles with even lower performance. Maintenance is higher for the engines/mechanical drive trains, and the equipment is arguably less reliable and wears out sooner than all-electric. Yes, wires are expensive to build and maintain too, and LRV equipment has to be kept separate from freight which is an issue with operations like WES and SMART; but electric operating characteristics allow greater service frequency and more stations/faster average speeds (pick one of the latter if you go to light rail station spacing or less) than with diesel power. The freight line electric issue can be finessed with standard MU equipment like Caltrain is planning to get, and as is common on the East Coast.

Bottom line as I see it is that locomotive-hauled (especially diesel) trains are useful mainly as a quick way to get commute and very-basic (hourly or longer, off-peak) service, with relatively long distances between stations, onto an existing line that needs little extra work. Frequent all-day service needs electrics, really.

IOW, the Metro Gold Line was the right thing to put there.