Flangeway

The factors in determining the width of flangeways between check rails and the main rail are the thickness of the wheel flange and the clearance allowed […]

The use of a high-temperature gas torch for melting the ice out of the check-rail flangeways, was found to be effective, although somewhat tedious; neglect of this precaution may cause derailment, [...].

Insure that ample flangeway is available between the open point of switch and the stock rail; this is controlled by flange width of crane wheels using the track system

Available at most hobby shops, this tool allows you to check track gauge, flangeway spacing and width, and many other dimensions.