- Used other than as an idiom: see common, crossing.
- (rail transport) The part of a railway switch or turnout where the running-rails cross; a frog.
1888, American Society of Civil Engineers, Transactions of the American Society of Civil Engineers, volume 18, page 239:
- The frogs are made of steel rails; for all common crossings a check rail is placed on each side, at least 12 feet in length, and much longer in special cases. The narrowest part of the throat of the frog is 1¾ inches wide.
1943, Permanent Way Institution, British Railway Track: Design, Construction and Maintenance, page 52:
- From Fig. 22 it will be seen that a common crossing consists of four rails, i.e. one point rail, one splice rail, and two wing rails.
1991, International Railway Congress Association, Rail International, volume 22, page 40:
- During the study, various railways will be investigating different types of common crossing, such as Vario, manganese steel, glued or bloomed common crossings and common crossings with glued or welded fishplates.
1966, International Railway Congress Association, Monthly Bulletin (English edition), volume 43, page 397:
- The drawback of these common crossings lies in the difficulty of welding them to the adjacent rails.