Many welding applications in the transport industry are for very long welds, as shown here in this railway carriage application.  Another similar example is the shipyard panel line.  There is usually some distortion in the way the parts are prepared or fitted together which means that a weld tracking system is required.  Meta has experience in many different transport welding systems.

One modern approach to some of these long straight welds, applied for example in aerospace structures, is to use friction stir welding.