,transcribed from the ,june #aibb edition by ,david ,price1 email ccx#jgdpglaf4org 7#a1jjj--,w4 #aib-g-bb74 ,great ,western ,railway4 99 99 99 99 99 ,,instructions4 99 99 99 99 99 ,,superelevation ,,or 8,,cant40 ,,expansion ,,of ,,rails4 ,,gauge ,,and ,,checking ,,of ,,curves4 99 99 99 99 99 ,w4 ,w4 ,,grierson1 ,chief ,engineer4 ,,paddington1 ,june1 #aibb4 ,,superelevation ,,or 8,,cant40 ,to be given to the ,outer ,rail in ,curves ranging from #f to #bjj ,chains ,radius4 ,offset ,radius ,,minimum 8,,cant40 ,,maximum 8,,cant40 7,length of of ,curve4 ,cord #ff ft47 ,outer ,for a ,outer ,for a rail maximum rail to maximum to be speed of be speed of raised4 raised4 ,inches4 ,chains4 ,inches4 miles per ,inches4 miles per hr4 hr4 #af #f #c #bj #f #be #aj #aj #c #be #e #cj #f #ae #c #cj #d #ce #e #bj #c #ce #e #de #d #be #b #ce #d #de #c #cj #c #dj #d #ej #b #ce #b #dj #d #ej #b #dj #b #dj #e #fj #b #de #b #de #d #fj #b #ej #b #de #e #gj #a #fj #a #de #d #gj #a #gj #a #de #d #gj #a #hj #a #ej #c #gj #a #ij #a #ej #c #gj #a #ajj #a #ej #b #gj #abj #a #ej #b #gj #adj #a #ej #b #gj #afj #ej #a #gj #bjj #ej #a #gj ,the amount of 8cant0 to be given to a curve is governed by the speed at which trains run over it1 and in no case must the raising of the outer rail in ,running ,lines be less than is given in the column headed 8,minimum ,cant10 except where necessary to meet special cases1 as at switches1 crossings and junctions4 ,in curves on falling gradients where high speeds are run1 the outer rail must be kept well up1 while on rising gradients a lesser 8cant10 but within the limits of the latter1 must be given4 ,on gradients on single lines the outer rail of curves must1 as a rule1 be raised to suit the speed of descending trains4 ,the superelevation must be gradually attained at the rate of #a inch in each #ff feet length as the curve is approached1 maintained uniformly over the whole length of the curve1 and run out after passing the curve in the same way4 ,on reverse curves1 or curves with very short pieces of straight between them1 the 8cant0 must be made gradually on the curves commencing at the middle of the short piece of straight in the latter case4 ,,explanation4 ,stretch a cord measuring exactly a chain 7#ff feet7 across the inner side of the curve1 and measure the distance 7,c ,d7 between the inner edge of the rail and the cord1 as shewn in sketch below4 ,look for this measurement in the column headed 8,offset10 opposite to which1 in the column headed 8,radius of ,curve10 will be found the radius of the curve in chains2 and in the columns headed 8,minimum ,cant0 or 8,maximum ,cant0 will be found how much the outer rail is to be raised above the inner one1 according to the speed of trains4 ,picture3 ,diagram showing the above curve1 offset etc4 ,,example4 ,suppose the distance between the inner edge of the rail and the cord at ,c ,d is found to be #b inches1 the column headed 8,radius of ,curve10 shews it to have a curve of #dj chains radius2 and those headed 8,minimum ,cant0 or 8,maximum ,cant0 will shew that the outer rail must be raised #b inches higher than the inner one for a speed of #dj miles an hour1 or #e inches for a speed of #fj miles an hour4 ,,expansion ,,of ,,rails4 ,in laying the #de ft41 #dd ft4 #f in41 #ci ft4 #e in41 #cb ft41 #bi ft4 and #bf ft4 lengths of rails1 the following spaces must be left at the joints1 according to the temperature for the expansion and contraction of the metal1 viz43-- ,air ,,nature ,,of ,length of ,rail4 ,temperature4 ,,weather4 7,degrees ,fahrenheit47 #de #j #cb #j #dd #f #bi #j #ci #e #bf #j #hj ,in hot ,summer #e_/cb #c_/cb weather #fj ,in moderately #c_/af cool weather #cj ,in cold ,winter #ac_/cb #i_/cb weather ,for laying down new permanent way iron expansion gauges1 equal in thickness to the respective spaces given1 to be used4 ,wooden gauges must on no account be allowed4 ,the expansion granges must1 as far as possible1 be allowed to remain in the joints until they are properly fished up1 and the road slewed into its proper line and 8topped40 ,,gauge ,,and ,,checking ,,of ,,curves4 ,when laying new lines1 or relaying in curves of #aj chains radius and above in plain line work1 the gauge of the road must be laid to the standard width of #d ft4 #h in41 but in curves of less than #aj chains radius1 worked over by ,passenger and ,goods ,trains1 the gauge may be slightly eased according to the radius of the curve and other circumstances4 ,the check rail in plain road is to be second-hand bull-head rail1 and all curves of ,passenger lines of #aj chains radius1 and under1 must be continuously checked2 the check rail in all cases to extend1 where possible1 for a length of #ej feet or thereabouts outside the commencing and terminating points of the curve to be checked4 ,continuous check chairs for plain road1 are of two patterns1 one allowing a clearance of #a in4 to be used in curves of #aj chains radius1 and the other allowing a clearance of #b in4 to be used in curves under #aj chains1 both rails in each1 case being level on top4 ,in sharp reverse or 8,s0 curves in plain line work where a piece of straight line cannot be given1 the junction of the two curves must be laid with check rails on both sides1 each check to be laid to cover the other for a safe distance4