More road spikes

26th Ave E at E. Galer St., Seattle. These two spikes are right where the road bends. Around the corner, south of this intersection on 26th, there is another spike. In the short time I stopped to snap this picture, three bicycles came by. How do these things get left by the city in the road? I think I have an eye for them, but most bicyclists and pedestrians probably don't even see them until they hit one.

Update: They're still there.