All other arguments aside, I've had the idea on occasion that railroads should *always* include a bike/walking path with their bridges in order to give people a safe place to cross instead of tempting them to walk on the tracks across the bridges (the scene in Stand By Me comes to mind).

Of course, while the death potential goes down, the lawsuit potential goes up (as someone mentioned) in the event something happens on the bridge (don't you love how our society works?)--on a purely rail crossing, the railroad simply claims that the pedestrian was trespassing and disclaims any liability.