I was one of the naysayers. We had express buses for commute before light rail, and they had a fairly stable 80% or so occupancy (rarely standing room). So figuring 6 buses at 45 seats, that was 270 riders a day. Plus another line with a variable schedule using a mini-bus that served a major employer and connected with light rail down the line a ways. So figure maybe 400-500 riders a day, each way. You could (at the time; seats have been removed since then for bicycle and more wheelchair space) put the entire express bus ridership on 1 or 2 light rail trains, and the entire ridership, period, on 3 or 4. So while on the whole I liked the idea of light rail access (would be all day, rather than just a commute times) I didn't expect heavy usage at our end of the line. Obviously, considering the minimal facilities provided, neither did the city.

By day 3 it was standing room on every commute-period train, all the station parking lots were full by the time the 6AM train (the 3rd one of the day) left, and people were griping about lack of parking (local bus didn't start running until a 7AM train connection; one parking lot was expanded about a year later and immediately filled). The people at intermediate stops griped about lack of space too, and mostly had to switch their personal schedules to use the in-between trains that turned back early. Totally different picture than the prior bus usage would have suggested. Even allowing for the cash fare reduction (buses had a premium fare).

My mind has changed. A dedicated transit line (usually rail, but the Orange Line in LA shows that real BRT (not just limited-stop buses on the street with queue-jumps and signal preemption) can work in a similar way) does attract traffic that otherwise wouldn't use transit. True, not every line works as well as the most optimistic estimates (VTA's system) but sometimes that's just for lack of planning or concentration on cheap, and the lines do still work at least as well, and usually better, than trunk-line buses on the street.

So I wish the Gold Line extension well. It looks like the demand is there, and having a train zipping by the stopped freeway traffic, in clear view, is good advertising (BART has done that for years, and it works).