You deal with rain grooves in much the same way as a gusty crosswind, relax and let the frame geometry deal with it. Grated bridges are a bit worse, especially ones like that between Beaver Falls and New Brighton PA. That one crosses the Beaver river at an angle, but the grate is square to the river bank so your bike tends to wander over into the oncoming traffic.

Let's hope there's intelligent life somewhere in space 'cause it's buggar all down here. -- Monte Python