CWR refers to the way in which rail is joined to form track. Through CWR, rails are welded together to form one uninterrupted rail that may be several miles long. Although CWR is normally one continuous rail, it may contain joints for one or more reasons (such as insulated joints that electrically separate track segments for signaling purposes).

Regulations governing the installation and maintenance of CWR were first issued in 1971 as part of the Federal Track Safety Standards. Over the subsequent decades driven by legislative mandates together with knowledge gathered from the industry and FRA’s own research, the CWR regulations have expanded. Today railroads are required to adopt and comply with CWR programs that cover procedures for installing, adjusting, inspecting, and maintaining CWR, as well as inspecting joints in CWR track.