What's this sign on the Embarcadero across from the San Francisco Ferry Building trying to say?
It's trying to alert drivers to a streetcar track crossing, as well as the presence of bicyclists and motorcyclists in the area. Still, it's one of the most complex pictographic warning signs I've seen. It may be trying to communicate too much without words.
Several people have written to say that they think the sign is trying to say "there's a track crossing at an angle". It is true that part of a wye emanating from a streetcar stop is on this side of the Embarcadero. If that's the intent of the sign, then I'd think that two tracks should be shown. The angle of the tracks shown on the sign is 90 degrees opposite from the first set of tracks that a bicyclist or motorcyclist would actually encounter.
Also note that the tracks are streetcar tracks, which do not have wooden ties and are more-or-less flush at street pavement level (while still presenting a hazard to some modes of traffic). So the illustration of the track is a bit misleading in another way.
Anyway, I think the basic point is still valid: this sign is combining symbols in an unexpected and complex way, leading it open to multiple interpretations. The use of words would help a lot in this situation, in my opinion.