You oughta see the gizmatron that they use when they resistance weld them.
I use tiny cadwelds when I electrically bond the rails together in the gate circuits.
This link has a brief history
http://www.hollandco.com/Crane_Rail...body_flash_butt_welding_of_crane_ra.html TW
Edited because I always think of a better way to say it after I have posted
[This message has been edited by Trainwire (edited 02-21-2006).]