Oh, yeah.. Train tracks. I went down maybe four time this past year, on two of those occasions I was crossing train tracks in the rain. Unless you are 'perfectly' perpendicular to the tracks - the rear wheel never fails to catch and slide along the rail and toss you down to the wet pavement.. especially at speed - and especially when there may be a train coming. Last year my bike almost got run over by a trolly after I got thrown off.. but luckily he stopped in time for me to go get it off the tracks.