213.53—Gage.
        
        (a) 
         Gage is measured between the heads of the rails at right-angles to the rails in a plane five-eighths of an inch below the top of the rail head.
    
    
    | Class of track | The gage must be at least— | But not more than— | 
|---|---|---|
| Excepted track | N/A | 4′101/4″. | 
| Class 1 track | 4′8″ | 4′10″. | 
| Class 2 and 3 track | 4′8″ | 4′93/4″. | 
| Class 4 and 5 track | 4′8″ | 4′91/2″. |