M10 (4) Rail mounted Gantry crane - N GAUGE -Picture includes illustration of model when completed The model contains parts to build one gantry crane, it requires construction and painting. Rail Mounted Gantry cranes (RMG) were first introduced in the 1970's and are still in widespread use today. The RMG travels along fixed rails to lift, transfer and stack 20' to 40' containers using a top lift spreader. Sometimes these have additional drop arms for more specialized loads (such as box type