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.

Continuous check chairs for plain road, are of two patterns, one allowing a clearance of 1¾ in. to be used in curves of 10 chains radius, and the other allowing a clearance of 2 in. to be used in curves under 10 chains, both rails in each, case being level on top.

In sharp reverse or “S” curves in plain line work where a piece of straight line cannot be given, the junction of the two curves must be laid with check rails on both sides, each check to be laid to cover the other for a safe distance.