Crossing Tracks Safely [Off the Beaten Path]

A while ago, we wrote about railroad tracks and how narrow tires can fall into the gap between rail and pavement. We suggested that wide tires are safer, because they don’t fit into that gap. In the comments section, a few riders reported that they or others had crashed on tracks even with wide mountain bike tires. How could this happen?
Every time I ride over railroad and streetcar tracks with my 42 mm-wide Grand Bois Hetre tires without undue concern or special precaution, I wonder what is going on when people crash on railroad tracks. I believe there are several mechanisms at work.
1. Falling into the gap next to the rail
The most obvious problem is a tire that is so narrow that it fits comfortably into the gap between rail and pavement. (This gap is necessary because railroads use flanged wheels to keep their rolling stock on the tracks.) If the rider crosses the tracks at an oblique angle, the tire can fall into the gap. The bicycle no longer can be steered and crashes.
One piece of advice you often hear is to line up your bike perpendicular to the tracks, to prevent the tire from falling into the gap.