having ridden over a number of bridges in the car lanes (thanks critical mass!) i've been able to check out the expansion joints used there. left uncovered, they're impossible to ride over.

they're like a set of interlocking fingers, much like this picture, except in the case of some bridges (the manhattan bridge, i remember), the gaps are so wide, your wheel would just fall right into them if you tried to ride over.



you'd think that a much longer, lower type of rolling speedbump could be used and maybe paved over.