True enough about not mapping for the renderer, but the wiki gives conflicting answers. Yes, I know, documentation always lags behind reality. But the problem is that it is true that highway=crossing and it is also true that highway=traffic_signals. Which one should be used? If I use highway=crossing with crossing=traffic_signals then mapnik doesn’t show any obvious indication it’s a crossing and doesn’t show traffic signals either. That’s flawed rendering whichever way you look at it.
Those lights don’t just control pedestrians, they also control traffic. Arguably it could be “highway=traffic_signals; crossing”.
Not showing the lights isn’t a gigantic problem on the 3 sets I’ve done so far (the crossings aren’t at junctions), but is on the other set of lights in town. They control a junction on the town bypass, and before the lights were installed a few years ago there were many accidents there. Those lights are important. They also control pedestrian crossings. So if I map them the “correct” way those lights vanish from an important junction on some renderers.
I know, don’t map to the renderer. But what I used isn’t (to me) obviously wrong, even after alester’s comment, because in that situation there’d be a railway=crossing.