The pendulum has started to shift on this in the last couple of decades, and light rail investment seems to be the new "it" thing for happening cities. Though Toronto's ambitious light rail network has been reduced to little more than a damp squib thanks to hizzoner Rob Ford, cities that are not saddled with a leader who reflexively opposes street-sharing light rail or streetcars are making real progress. In Los Angeles, test trains have started running on the first segment of the new Expo Line; in Cincinnati, planning continues on a new downtown streetcar system; and in Washington, DC, work on the DC Streetcar is continuing. With the high expense involved in tunnelling, and considering the economic chickens that will soon be coming home to roost across the United States and Canada, most rapid transit projects in the coming decades will likely be realized in light rail.
But it's not always a smooth ride. Putting light rail trains on ground level forces them to reckon with an unpredictable force - drivers! Take, for example, the video below - a series of train's-eye-view videos from Houston's METRORail, a light rail system that started operations in 2004, and which I was reminded about by the Buzzer's latest link roundup.
Kind of pathetic, isn't it? Take the second one, that Dodge pickup truck. There's no way you can expect me to believe that the driver did not see the big, shiny, ninety-foot long light rail train bearing down on it, and turned anyway. What I find more likely for all of these instances is that they come down to driver error - these accidents can be easily explained by the driver not bothering to check their mirrors and blind spot before turning - something that was hammered into me during my driver's education classes.
I've encountered a few people who argue that examples such as these demonstrate why light rail and vehicular traffic shouldn't share the same space. Personally, I think that's bunk. You could argue that the video above owes a lot to Houston's drivers being unused to the presence of these speeding light rail trains sharing their roads, but you can only take that so far. If this had been, say, a bus that the cars had turned directly into the path of, would that be justification for removing buses from the roads?
Phoenix Metro Light Rail trains may have a curb separating their tracks from the street, but there are still plenty of opportunities for a determined driver to get smashed up by one.
Light rail is a complicated subject. To stand opposed to it because ignorant drivers who lack situational awareness might drive right into it is a problem - if that's the case, the issue of light rail is secondary to the issue of getting them off the road, before they smash up a school bus.