The design of connections is as important to the safety and reliability of steel railway superstructures as the design of the axial and flexural members that are connected to form the superstructure. Connections in modern steel railway superstructures are made with welds, bolts, and/or pins. Welding is the metallurgical fusion of steel components or members through an atomic bond. The arc welding processes most commonly used for railway superstructure steel fabrication are shielded metal arc welding (SMAW), submerged arc welding (SAW), and flux cored arc welding (FCAW). Stud welding is essentially an SMAW process made automatic. The electrodes for structural steel welding are specified for the base metal and welding process to be used in the qualified welding procedure specifications (WPS). Welds are groove, fillet, slot, or plug welds. Bolting is the connection of steel components or members by mechanical means. Bolted connections are relatively easy to make and inspect.