I think they use thermite at the shop for the quarter-mile lengths they take to the site. They use a arc (?) welder on a special truck (frame #9 and more later) when they connect the longer sections ric > On Jan 2, 2020, at 7:57 AM, Sonny Carter via LUG <lug at leica-users.org> wrote: > > I think they are thermite welding the joints