Suppose the distance between the inner edge of the rail and the cord at C D is found to be 2½ inches, the column headed “Radius of Curve,” shews it to have a curve of 40 chains radius; and those headed “Minimum Cant” or “Maximum Cant” will shew that the outer rail must be raised 2¼ inches higher than the inner one for a speed of 40 miles an hour, or 5⅛ inches for a speed of 60 miles an hour.
EXPANSION OF RAILS.
In laying the 45 ft., 44 ft. 6 in., 39 ft. 5 in., 32 ft., 29 ft. and 26 ft. lengths of rails, the following spaces must be left at the joints, according to the temperature for the expansion and contraction of the metal, viz.:—
Air | NATURE OF WEATHER. | Length of Rail. | |
|
| 45′ 0″ | 32′ 0″ |
80 | In hot Summer weather | 5/32″ | 3/32″ |
60 | In moderately cool weather | ¼″ | 3/16″ |
30 | In cold Winter weather | 13/32″ | 9/32″ |
For laying down new permanent way iron expansion gauges, equal in thickness to the respective spaces given, to be used.
Wooden gauges must on no account be allowed.
The expansion granges must, as far as possible, be allowed to remain in the joints until they are properly fished up, and the road slewed into its proper line and “topped.”
GAUGE AND CHECKING OF CURVES.
When laying new lines, or relaying in curves of 10 chains radius and above in plain line work, the gauge of the road must be laid to the standard width of 4 ft. 8½ in., but in curves of less than 10 chains radius, worked over by Passenger and Goods Trains, the gauge may be slightly eased according to the radius of the curve and other circumstances.
The check rail in plain road is to be second-hand bull-head rail, and all curves of Passenger lines of 10 chains radius, and under, must be continuously checked; the check rail in all cases to extend, where possible, for a length of 50 feet or thereabouts outside the commencing and terminating points of the curve to be checked.