A while back, I referred to Washington, DC's ongoing mixed-traffic streetcar as the worst transit project in America. City Lab's David Alpert fired back, accusing me and other streetcar critics of making the perfect the enemy of the good. The point about the DC streetcar (and this is often true of mixed-traffic streetcar projects) is that they're not just expensive, they're actually bad for mass transit.
Consider this update on the streetcar's progress from Michael Laris at the Washington Post who reports, among other things, that "buses are facing significant delays behind the streetcars, which are making regular practice runs to simulate everyday operations."
That's the fundamental problem with the H Street streetcar. It's not just that the city is spending a lot of money to build a transit line that will be less useful than the X-2 bus whose route will overlap with it. The city is spending a lot of money on a transit project that will slow buses down. Mixed-traffic streetcars have a lot of appeal to real estate developers, because nobody likes to brag that their new condo project is near a bus stop.
But judged as actual transportation, this is not an imperfect project — it's a bad project. It's one that is making the city's mass transit network less useful to regular riders.
To be perfectly clear, this isn't an issue with streetcar technology per se. Something like France's Strasbourg Tram, which runs mostly in its own dedicated lanes, is very much a useful transportation project. It is more expensive than a bus line with dedicated lanes, but it also provides a superior level of service to such a bus. It's a perfectly normal tradeoff between how much money you want to spend and how nice a facility you want to get as a result.
But in mixed traffic, buses aren't just cheaper than streetcars. They're better, because they can go around obstacles rather than getting stuck behind them.