1

1.0 INTRODUCTION

In a developing country like India, the contribution of railway transport towards the economic growth is immense as other modes of transport i.e. roadways, airways, inland waterways etc. are not available at reasonable rates and in sizable quantity to cope up with the quantum of traffic. The inland waterways are yet to be explored, airways carries very little traffic, roadways carries short distance traffic more eff iciently and the railway has to deal with the bulk of traffic. In recent past, the railways in India have started losing even the long distance traffic which is being hauled by the roadways. In order to move the traffic efficiently and promptly, it is felt that the speed of the rail transport shall be augmented. As a result, today there is a “cry” for high speed. Turnout, an essential feature of the track-structure for diversion of traffic from one road to another, poses at present a tricky problem in the context of achieving reasonably high speed over the turnout. Ideally, speed over turnouts should be that speed at which the train would have run, had there not been a turnout to be negotiated. But this ideal requirement can not be fulfilled. Due to the inherent features of the turnouts which cause a sort of discontinuity in the track, the speeds on the turnout have been less than those permitted on the mainline. The turnouts are thus considered bottleneck in increasing train speed.

2.0 NEED FOR HIGHER S PEED ON TURNOUT Compared to the speeds over turnouts on advanced foreign countries, the speeds on turnouts on Indian Railways are restrictive. Through running trains lose time when they have to run through the loop. M any times, running through the main line may often not be possible as at many stations, the platform may be on the main line and some passenger train may be standing on it. Sometimes, goods train may be standing on the main line due to insufficient loop capacity . At some locations, like points on the main line in big yard which are far away from the station, junction between double and single line where trains do not stop, Y- junction between important main lines, crossovers between slow and fast lines for the same direction on quadrupled section, high speeds on turnouts are required. At stopping stations, only the speed which the train will attain due to brakes being applied well in advance will be required on turnout.

Achievement of higher average speeds and line capacity without increasing the maximum permissible speed is possible by increasing speeds on turnouts. Time loss due to restrictive speeds on turnouts can be gauged from the following table-

2

Maximum sectional speed ( kmph)

Speed over T/O ( kmph)

Time Lost in Acceleration & Deacceleration (minute)

Time loss for each 100 m ( minute)

Time loss for one loop (700 m length) (minute)

75 1.2 0.04 1.48 50 1.8 0.06 2.22 30 2.95 0.12 3.79

105

15 4.8 0.24 6.48 It is obvious that raising speeds over turnouts can bring about huge saving in running time. In view of policy of increasing sectional speed of certain routes up to 150 kmph, increasing speed potential on turnouts becomes even more important. Attempt has been made in this paper to scrutinize the existing types of the turnout layout on the Indian Railway in the context of the design principles and the practical consideration for improvement and to recommend the proposal for having the desired speed on the turnout on the economic consideration.

3.0 TURNOUT & ITS DES IGN

A turnout is a device consisting of a pair of points (for switches) and a crossing to enable railway vehicle to run without interruption from one track to another. A turnout thus primarily consists of a pair of switch assembly with the crossing assembly. Design Criteria - Turnout design is governed by following criteria - • Safety • Economy • Maintainability

Running Rails

3

4.0 FACTORS AFFECTING S PEED OVER TURNOUTS Various factors limiting speeds over turnouts are as follows-

A-Kink in the turnout route at the toe of switch rail B-Entry from straight to curve without transition C- Lead curve without super-elevation D-Entry from curve to straight without transition E-Gap at the V of crossing

4.1 Sudden Change Of Direction At The Toe Of Switch

There is an angle between the gauge planes of switch and stock rails at toe of switch. The sudden change in the direction of travel of vehicle at toe gives rise to lateral accelerations in the vehicle, f lange forces on the track and discomfort to passengers. The only way to mitigate the effect of this lurch is to reduce the entry angle to as small a value as practicable.

4.2 Change From Straight To Curve Without Transition Speed over turnout is affected by the geometry of the lead curve which is normally a circular curve without any transition. This factor is of importance in case of straight switches. With curved switches, this factor is somewhat eliminated at position B but at position D, a similar situation continues. The sudden change of curvature from infinity to a certain value gives rise to lateral accelerations.

4

4.3 Non-Provision Of Superelevation On Lead Curve

The motion over the lead curve is controlled by the geometry of the lead curve which is circular curve without any superelevation and it’s tangential to the straight length of the switch and the straight length of the crossing ahead of the theoretical nose of crossing. The permissible speed has, therefore, to be restricted so that maximum permissible cant deficiency is not exceeded.

4.4 Entry From Curve To Straight Without Transition

The lead curve is generally circular curve without any transition and is tangential to the straight length of the theoretical nose of crossing. Therefore, speed over lead curve is to be restricted due to non-provision of transition.

4.5 Gap At The V Of Crossing

The gaps in the running rail at the nose of crossing are a source of very high vertical acceleration. The motion over the gap at the V of the crossing does not create any serious problem. There is usually no restriction of speed over the straight path so far as the geometry of the turnout is concerned, the speed being limited by the standard of interlocking. Since the motion on turnout over V of crossing is identical to that on the straight so far as crossing is concerned, there should naturally be no restriction of speed on the turnout side. Experience of many years has also provided that the motion on either side of the road at the crossing are identical. For very high speed beyond 200 kmph, movable nose crossing is adopted.

5.0 OTHER LIMITATIONS OF CONVENTIONAL TURNOUTS ON IR 5.1 SWITCH PORTION

5

• Twist in track due to tongue rails being 6 mm higher than the stock rail. This introduces twist for both the straight as well as turnout. The tongue rail for part of its length is higher than that of stock rail by 6 mm as this reduces the amount of undercut in the foot of tongue rail.

• Twist in the stock rail occurs due to its having been kept vertical whereas

the track rail in the approaches is canted at 1in 20. • Widening of gauge between theoretical toe of switch and actual toe and

then change over suddenly to exact gauge at the actual toe. • The tongue rail is projected outside the gauge face of stock rail by about 6

mm posing an obstruction in the path of wheel. The centre line of the web of tongue rail coincides with gauge face of stock rail in closed position.

• Outer fastenings of the stock rail are not adequate to withstand the heavy

lateral force generated during entry of the vehicles in switch portion. • At present, curved switches are manufactured out of ordinary rails and

they are thinner and longer than the straight switches. As such, the curved switches are more flexible and show a tendency to excessive vibrations under traffic. Their thin tips are susceptible to early damage.

• Indian railways curved switch designs are of intersecting type.

5.2 LEAD PORTION Due to non-provision of superelevation, excessive wear on the outer rail of lead curve takes place.

5.3 CROSSING PORTION • Built-up crossings are non-monolithic in nature. As a result, relative

movement of various components takes place which causes wear.

Built-up crossing

6

• The legs of crossings are manufactured as straight lines. These crossings result in problems of integrating them with curved main line track and also within curved lead portion.

• The V has to bear double the load compared to adjacent running rails, however, its section is lesser than that of adjoining running rails.

• Wooden/ST sleepers get bent in the middle under the crossing.

6.0 TURNOUT FOR HIGH S PEED Up-gradation in turnout technology in the advanced railway systems has been guided by the following considerations- • Higher speeds on straight and curved tracks with reasonable level of

passenger comfort. Designs have been evolved for a speed of over 200 kmph on curved track.

• Least life cycle cost with minimum traffic interruption for repairing and reconditioning.

• Track geometry maintainability comparable with the normal track • Safety and comfort • Timely warning before failure • Planned maintenance without emergencies

6.1 By reducing the switch angle, entry gets smoothened and flange force gets reduced. The small switch angle is obtained by providing curved switches. For speeds higher than 45 kmph, tangential type of switches are used over foreign railways. In tangential type, very small switch angle is possible compared to intersecting type.

.

INTERSECTION FORM

TANGENTIAL FORM

NON-INTERSECTION FORM

7

6.2 In order to provide lateral rigidity to switch rails, and prevent its vibration under traffic, thick web switches are used.

6.3 In some countries, head hardened rails on outer rail of lead curve are used to check wear.

6.4 In order to eliminate the shocks at the heel of switch and the toe of the crossing due to untransitioned lead curve, transitioned lead curves are used. In transitioned lead curves, the rate of application of lateral acceleration is gradual and passenger discomfort is reduced.

6.5 Crossings can be either fixed or movable type. In straight type, the lead curve ends before the toe of crossing whereas in curved type, the led curve continues over the crossing. Curved crossings eliminate the shock due to change in alignment from lead curve to straight at the toe of crossing. The crossings with moveable nose are generally used in turnouts with speeds 160 kmph and above.

6.6 The check rails are independently secured to the nose of crossing. Also, the check rails are raised above stock rails by 45 mm, as a result, greater width of wheel comes in contact with check rail and grinding is better.

7.0 CALC ULATION OF PERMISS IBLE S PEED OVER TURNOUT

The permissible speed over the turnout is the minimum of the following three speeds

• Permissible speed due to non-transitioning of the lead curve • Permissible speed due to non- canting of lead curve • Permissible speed to obtain desirable values of lateral forces and acceleration

at entry Entry conditions are the most important and critical consideration in determination of speed on turnout. All attempts to find permissible speed over turnout finally boil down to finding the permissible speed for ensuring satisfactory entry conditions.

7.1 Permissible Speed Based On Non-Transitioning Of Lead Curve

Non-transitioning of lead curve results in sudden change of curvature and gives rise to lateral acceleration. Speed is given by following formula- V=4/5 × 4.4 �R-70 Speed V is in kmph and radius R is in m.

8

7.2 Permissible Speed Based On Non-Provision Of Superelevation On Lead Curve

The lead curves on Indian turnouts are not provided with superelevation. The permissible speed is therefore, restricted so that maximum permissible cant deficiency is not exceeded.

V= � R×C / 13.76 Where speed V is in kmph, radius R is in m and cant deficiency C is in mm.

7.3 Permissible speeds for various types of turnouts calculated on criteria mentioned in para 7.1 & 7.2 are as follows- TURNOUT SWITCH

ANGLE SPEED DUE TO NON-TRANSITIONING (KMPH)

SPEED DUE TO NON-PROVISION OF SUPERELEVATION (KMPH)

1 IN 8.5 ( straight switch)

1° 34’ 27” 43.6 35.8

1 IN 8.5 ( curved switch)

0° 47’ 27” 45 36

1 IN 12 ( straight switch)

1° 8’ 0” 68 50

1 IN 12 ( curved switch)

0° 27’ 35” 69.4 51

1 IN 16 0° 24’ 27” 95.4 68.8 1 IN 16 ( sym. split)

0° 12’ 13” 138 97

1 IN 20 0° 24’ 27” 122 86.4

7.4 Permissible Speed Based On Entry Conditions

The subject matter was discussed vide item number 488 of 38th TSC. A formula was evolved for calculating permissible speed based on entry conditions. In this method, the speed is determined on the basis of an abrupt change of direction and consequent thrust at the toe of switch. This involves determination of the radius of a virtual curve at the toe of switch corresponding to a chord C equal to bogie centers of a passenger coach and versine v as measured at the toe of switch when the above chord is placed symmetrical to the toe.

9

A T

BC

CHORD LENGTH AB = DISTANCE BETWEENBOGIE CENTRES

VIRTUAL CURVE THEORETICAL TOE OF S WITCH

STOCK RAIL

SWITCH ANGLE

V ERSINE

Let R be the radius calculated by putting the above values in the formula

v = C2 / 8R The virtual radius Rv is then taken as R/2 to allow for 100 % impact effect. The permissible speed is then calculated so that cant deficiency does not exceed the permissible value of 75 mm. v = Versine V = Permissible speed C = Distance between bogie centers Rv = Radius of virtual curve Rv = R/2 V = � R×C / 13.76 Where V is in kmph, R is in m and C is in mm.

As per this method, versine is same for straight or curved switches. Entry conditions are far superior with curved switches. The speeds calculated with this formula for 1 in 16 and 1 in 20 turnouts are ridiculously low. The subject was again discussed in 41st TSC. TSC asked RDSO to conduct detailed study in this regard.

8.0 O.R.E REPORTS The O.R.E. have examined the ‘”Guiding Principles for the Design of Points and crossings” vide question D-72 and the results of their study and experiments are contained in their reports 1 to 6 on question D-72. The O.R.E. had gone into the problem by detailed analysis taking all parameters of track geometry and vehicle suspension and they obtained the solutions by using computers. The results of theoretical analysis have been verif ied with experiments. M ain observations of the reports are as under- • The lateral acceleration determines the comfort of riding, while the lateral

forces exchanged during the passage of wheels determine the

10

maintainability of switches. The value of permissible lateral force on turnout should be fixed on the basis of same limits of lateral loads which will ensure that the turnout does not entail unduly high maintenance effort.

• Permissible speeds on turnouts should be worked out by studying lateral

acceleration of vehicles affecting comfort and forces exerted on track. • The lateral forces and lateral acceleration are proportional to angle of attack

and speed. The values of lateral forces for typical values of angle of attack and various speeds are given below-

The total change in direction at the entry is made up of the angularity of axle, the switch angle and the increase in switch angle from the theoretical toe of switch to the actual point of attack and is termed a angle of attack. In the figure shown below, � is the angle of attack.

ST OCK RAIL GAUGE FACE

TOE OF SWIT CH

SWITCH GAUGE FACE

POINT OF ATTACK

MAXIMUM VALUE OF LATERAL FORCES (TONNES )

ANGLE OF ATTACK

S PEED 30 KMPH

SPEED 45 KMPH

S PEED 60 KMPH

0° 12’ 0” 2.4 3.0 4.0 0° 24’ 0” 4.9 5.10 6.50 0° 34.4’ 0” 7.0 7.50 10.0 0° 41.5’ 0” 10.0 11.50 14.9

Flange forces depend to a greater extent on the angle of attack than on speed.

• For the same angle of attack, the impact and lateral accelerations are more for entry into circular curve than for transition curve.

�

� �

�

�

11

• The angle of attack and the accelerations are higher for a stiffer track. • The angle of attack is made up of two components-

i) Due to angular position taken by bogie truck - This can be reduced by adoption of tighter gauge and less wearing tolerances and stiffer tolerances of wheel flange wear and axle boxes and horn cheeks and better constructional features of coaches and locos. This is difficult as the tolerance in the vehicle are based on many other considerations.

ii) Due to geometry of switch - This is the prepondering consideration for achieving riding comfort.

• The following switch entry angles were recommended for different

speeds-

S PEED S WITCH ANGLE 40 kmph 0° 40’ 30” 60 kmph 0° 25’ 0”

100 kmph 0° 15’ 0” 160 kmph 0° 8’ 0”

• Tangential type of switch is best suited as it gives small entry angles.

9.0 RDSO TRIALS 9.1 The RDSO conducted studies in early 1960s on the flange force exerted by the

Pacific & BESA type of locomotives on 1 in 8.5 & 1 in 12 turnouts with wooden and steel sleeper layouts.

9.1.1 Lateral forces measured by RDSO were as follows- TYPE OF TURNOUT LATERAL FORC E S PEED

1 in 8.5(straight) 13 T upto 24 kmph 1 in 12(straight) 11 T upto 32 kmph 1 in 12 (curved) 5.7 T upto 32 kmph

9.1.2 Slack gauge of 1/8” to 1/4” caused slight increase in lateral forces. 9.1.3 For 1 in 8.5 turnout, the track structure was found deflecting by about 4 mm on

turnout with steel sleeper and about 6 mm on turnout with wooden sleepers. 9.1.4 Lateral forces exerted by locos on turnout with straight switches exceed the limit

given by Blondel formula. HBlondel = 0.4 x axle load + 2 t

12

9.2 In 1971, RD SO undertook investigations on the speed potential of 1 in 8.5 and 1

in 12 turnouts with straight and curved switches and 1 in 16 and 1 in 20 turnouts with curved switches.

9.2.1 The field trials were primarily concerned with a measurement of the lateral

accelerations in the vehicles and the lateral forces on the track. 9.2.2 The rolling stock used were Locomotives = WP, WG, WDM 2, WDM4 Coaches = IRS, ICF

Wagons = BOX, CR 9.2.3 The lateral forces observed for 1 in 8.5 and 1 in 12 turnout are indicated below-

MAX.LATERAL LOAD 1 in 8.5 TURNOUT

MAX.LATERAL LOAD 1 in 12 TURNOUT

ROLLING STOCK

SPEED km/h

STRAIGHT CURVED STRAIGHT CURVED 10 9.65 6.50 8.65 5.00 20 12.60 6.70 11.90 5.00 30 15.45 8.40 13.60 5.40 40 19.15 11.20 14.50 8.00

WDM 2

50 - - 15.90 10.50 10 8.40 4.40 6.70 2.80 20 10.00 4.75 6.60 3.75 30 11.25 5.25 7.50 4.50 40 12.85 7.50 8.60 4.75

BOX (LOADED)

50 - - 10.00 5.00

The limiting value of lateral strength of track based on Prudhomes formula for 18.8 t axle load of WDM 2 would be - H Prudhomes = 0.85 (1+18.8/3) = 6.2 t The above value is applicable for lateral forces exerted over a length of 2 m. However in case of turnouts, the instantaneous value of lateral forces is to be considered. Here it may be permissible to apply Blondel`s limit for lateral forces, which is given by the formula H Blondelb = 0.4 x axle load + 2 t

Permissible lateral force based on Blondel formula for WDM 2 works out as follows -

13

= 0.4 x 18.8 + 2 t = 9.52 t

9.2.4 Lateral acceleration were well below the value of 0.3 g to 0.35 g permitted upto

40 kmph to 60 kmph. 9.2.5 Instrumented trials have revealed the following permissible speeds based on

lateral forces exerted by vehicles while negotiating the switches - TYPE OF TURNOUT

S WITCH ANGLE S PEED POTENTIAL

1 IN 8.5 (straight) 1° 34’ 27” 10 kmph 1 IN 8.5 (curved) 0° 47’ 27” 25 kmph 1 IN 12 (straight) 1° 8’ 0” 15 kmph 1 IN 12 (curved) 0° 27’ 35” 42 kmph 1 IN 16 and 1 in 20 0° 24’ 27” 55 kmph 1 IN 16 (high speed)

0° 17’ 11” >80 kmph

10.0 SIGNALLING & OTHER REQUIREMENTS FOR RAIS ING S PEED ON TOs

10.1 Speeds from 15 kmph to 30 kmph • Visibility of starter signal of loop line from a distance equal to the braking

distance of the heaviest train in the section has to be ensured. • In case, visibility cannot be ensured, Repeater signal should be provided.

10.2 Speeds higher than 30 kmph • Prior indication of signal aspect should be given to driver of approaching

train so that he can take appropriate action in time. • This will require modification in signalling and introduction of another

aspects to suitably pre-warn the driver. This will necessitate introduction of another aspect like f̀lashing yellow`.

• In view of increased speed through loops, detection of siding points taking off from loops has to be ensured through interlocking.

10.3 Other Engineering Requirements

• Turn in curves will have to be eased and strengthened • Track structure of loops will have to be improved • Raising of speed potential can not be on isolated station but will have to be on entire route selected for this purpose.

14

• Design adequacy of sand humps may have to be examined.

11.0 SPEED POTENTIAL OVER TURNOUTS ON IR

Speed potential on various types of turnouts on BG on Indian Railways are as under-

Description S peed Potential (kmph)

1 in 8 ½ TO with Str. SW 10

1 in 8 ½ TO with Cu. Sw.

25

1 in 12 TO with St. Sw

15

1 in 12 with conventional Cu Sw. 40

1 in 12 TO with improved Cu. Sw.

50

1 in 12 TO with Thick Web Sw.

50

1 in 16 Conventional TO with Cu. Sw.

50

1 in 16 Impr.TO with Cu. Sw. 65

1 in 20 Impr.TO with Cu. Sw.

85

1 in 8 ½ Symm. Split TO with Cw. Sw

40

1 in 12 Symm. Split TO with Impr. Cw. Sw

70

1 in 16 Symmetrical split with Cu.Sw

75

15

12.0 RECENT D EVELOPMENTS ON INDIAN RAILWAYS Following are the important developments that have taken place in recent past in regard to improvement of various features of turnouts - 1:12 B.G. 60 Kg HEAT TREATED WELDED CROSSINGS

In this type of crossing, the splice and point rails of Vee are joined together by welding process instead of conventional nut/bolts. Connection between the point and splice rails is achieved by fusion of weld metal with rail metal. Assembly is then heat treated.

ADVANTAGES • Thickness of Vee at nose increased. • Vee of the crossing becomes monolithic in structure. • Problem of relative displacements between splice and point rails is

eliminated. • Higher hardness of welding material is achieved. • Interchangeable with conventional built up crossing. SALIENT FEATURES • Developed for 1:12 BG 60 Kg for Indian Railway.

INSULAT IONERC MK II I

RUBBER PAD

SECTION AT ACTUAL NOSE OF CROSSING

WELDED VEE

A.N.C.

HEAT TREATED WELDED CROSSING (1 : 12 B.G. 60 Kg)

16

• ‘V’ made by welding points & splice rails. Electroslag process of welding adopted

• 400 mm length of wing rail on either side of ANC location (total 800 mm) heat treated to 330+/-20 BHN. This portion of wing rails considered to be most wear prone.

• 16 mm thick sandwitch plate used between point and splice rails. • Web thickness at ANC kept 49 mm ( 2 web +16 mm) • Special bearing plate used to fix crossing on sleepers with ERC. • 15 nos. special PSC sleepers used (SL no 64 to 78 ) to lay this crossing.

Other sleepers are same as in 1:12 layout to Drg. No. RDSO/T-4218. • About 2000 nos. of such crossings supplied to Railways between 1996-

2000 and have been laid on E,SE, C,N,W,SC & S. Railways. • Recently, 4 nos. of such crossings were modified to suit existing sleepers

and three have been laid at Bhopal for trial . After modifications, these crossings have been laid on existing PSC sleepers of CM S crossings with special liners of different sizes.

• Performance of these crossings is satisfactory. �

��������������� ������ ����������������� ������ ��������������� ������������������ �1:12 BG 60 Kg SWING NOSE CROSSING

In conventional crossing, there is vertical as well as lateral discontinuity between nose of crossing and the wing rails. This discontinuity results in high impact forces, jerks, discomfort and excessive wear. M oveable (or swing) Nose crossing eliminates this problem. It has a moveable nose similar to a switch which is moved through operation of a separate point motor simultaneously with the switches. It is necessary only if speeds > 160 kmph and intersections flatter than 1 in 32. With this crossing, check rails are not required. SALIENT FEATURES • Developed for 1:12 BG 60 Kg by M /S BM W, Jamshedpur. • Made by using normal 60 K g (UIC) rails. • ‘V’ of crossing is movable. It gives better riding. • Operation of swing nose is syncronized with the operation of switch as

per requirement of movement of traffic. • 260 mm stroke point machine is required for its operation. • It gives continuous, impact free and smooth path to moving wheels. • Nose thickness of this crossing at ANC is 72 mm i.e. full head width as

against 16.5 mm kept for normal built up/CMS crossing. As full rail head thickness is available throughout the crossing, its wear and tear is expected to be similar to that of any normal running rail.

• No weakness of reduced head in crossing. Full head can sustain impact as of normal rail.

17

• Can be used with 1:12 BG 60 Kg fan shaped PSC sleeper turnouts to drawing no RDSO/T-4218.

• This crossing requires 15 nos .of special PSC sleepers.

• One crossing laid at Gamaharia station of CKP division of SE Railway on 30.7.1997 has undergone 1mm wear.

• Negligible wear expected to give same life as that of a normal rail in track without any reconditioning etc.

• Bracket of point clamp lock has recently been modified and SE Railway have been advised to lay further swing nose crossing with this system.

• 100 sets have been procured and supplied to E, SE, C, W, & N Railway. Other Railway will shortly lay these crossings after getting feed back from SE Railway.

• This is a future generation of crossing suitable for high speed & heavy traffic routes

• Comments from field are awaited for further improvement of the design to serve its purpose of giving impact free movement to moving wheels.

WELDABLE C M S CROSSING CM S crossing cannot be welded with 90 UTS rails because of different chemical composition and metallurgical properties. Technology is now available for welding of conventional rails with CM S crossing by using a special welding process. In this process, a buffer rail is first welded on the end of CM S crossing by Flash Butt welding. The buffer rail is then cut leaving only 10-15 mm thick piece of buffer rail welded to CM S crossing. Thereafter, conventional rail is welded to this buffer rail p iece by Flash Butt welding. Conventional rails are then cut to make the overall length of weldable CMS crossing as per requirement.

A .N .C.

60Kg (UIC) RAIL PIECES

C.M.S.CROSSING.

WELDED JOINTS

WELDABLE C.M.S. CROSSING (1:12 B.G. 60Kg) SPECIAL ALLOY WELDED JOINTS

18

SALIENT FEATURES AND ADVANTAGES • Two rail p ieces on either end are welded with CM S crossing. • Special alloy steel is used for welding rail with CM S crossing. • The chemical composition of special alloy is such that it suits to welding

with CMS crossing as well as 60 Kg (UIC) rails. • Joints in vicinity of crossings are kept a bit away from ANC. • These rail p ieces can further be welded with adjacent rails to avoid joints

nearby crossing. • The technology of welding CMS with normal rail is not available in India

but available in abroad. • M/s Voest Alpine Austria had supplied 20 nos. of such crossings which

were laid on N.Rly in 1995 and still performing well with two reconditionings.

• M/s Cogifer France had supplied such crossings to DM RC. • Railway Board is planning to procure this technology from abroad in near

future. • With this arrangement , it would be possible to continue LWR through

turnouts.

19

THICK WEB CURVED SWITCHES ADVANTAGES OF THICK WEB SWITCHES

• No twist as top of tongue rail is in level with top of stock rail. • Lateral strength increased. • Sturdier due to thicker web. • Switch entry angle reduced – smoother entry. • Jerk at entry is reduced as tip of tongue rail is housed in a recess. • Higher speed potential ( 50 kmph for 1 in 12 layout). Two types of thick web switches have been used by Indian Railway. They are fabricated from imported asymmetrical rail section. Both are non-overriding type.

Zu – 1- 60 for 60 kg.

Zu – 2 – 49 for 52 kg. Following design using indigenous crane rails have been developed by RDSO.

1 IN 12 52 KG : RDSO / T – 5168 using CR 100.(Drg. Issued) 1 IN 12 60 KG : RDSO / T- 5222 using CR 120.(Drg. Not Issued)

Zu-2-49 thick web switches • About 600 nos. procured in 1984-1990 for wooden sleeper layout with 115

mm throw. • Were laid on E , SE, SC, S, C, & N Railways. • Had outlived lives about 10 to 12 times more than the life of conventional

switches. • Most of these switches were replaced by fan shaped PSC layouts

prematurely due to non availability of wooden sleepers for renewals. • Very less switches were replaced on account of wear. • Would have still given more life if wooden sleepers were made available • Four set of these switches were laid at Faridabad station of C. Railway

in 1985 on main line out of which three sets are still existing in track. • 320 sets were procured by KRCL in 1996-97 for PSC sleeper layout with

145 mm throw with SSD. Performance of these switches on KRCL is satisfactory

20

.

21

Zu-1-60 THICK WEB SWITCHES Salient features and advantages • 400 sets procured in 1996-2000 for PSC sleeper layout with 160 mm

throw and SSD. These switches were procured as per firms own design (five designs).

• Use of SSD, enable uniform gauge in switch portion, thus avoiding floating tight gauge and rattling of switch/stretcher bar fittings.

• With use of SSD, wear on tongue rail will considerably be reduced which in turn will increase the life of tongue rails.

• Point clamp locks with 220 mm stroke IRS Point machine are used which gives positive & direct locking of stock & tongue rail on high speed route.

• PSC sleepers will give more sound & uniform base than the wooden sleepers which will enhance its service life.

• Zu-1-60 thick web switches with 160 mm throw & SSD on PSC sleepers is expected to give more life as was achieved with Zu-2-49 TWS on wooden sleepers.

• As a policy, Railway Board has decided to lay thick web switches on entire ‘A’ route of Indian Railway. It has been planned to lay about 2000 sets of TWS every year. .Procurement of thick web switches is in process at Railway Board level.

• Initial procurement cost of thick web switches is about 3 to 4 times more than the cost of conventional 60 kg switches but considering its expected enhanced life by more than 12 - 15 times, it will certainly be economical in the long run.

• RDSO has developed design of 1:12 and 1:8.5 thick web switches with 160 mm throw and SSD for use on respective existing PSC sleepers so that TWS may be introduced on entire ‘A’ route as per planning by simply replacing the existing switch assembly by TWS switches.

• RDSO’s design of slide chairs for TWS are provided with ERC, leaf springs & wedge arrangement. With this system, LWR may also be continued through turnouts in future.

• DM RC has used canted turnouts in their project using 60 D rails for making tongue rails through M /S COGIFER FRANCE. This rail has special feature of flat bottom and top canted to 1:20. Stock rails are made canted by giving 1:20 cant in slide chairs. DM RC has continued LWR through turnouts at some of the location which is working satisfactorily .

22

HEAT TREATED SWITCH TIPS FOR 10125 mm CURVED SWITCHES BG 60/52 Kg ON PSC SLEEPERS

Tongue rails fitted with heat treated switch tips will have longer life. The switches wear fast at the tip due to reduced cross section. The life of switches can be increased by increasing hardness to about 450 BHN against the normal hardness of 270 BHN in case of 90 UTS rails. SALIENT FEATURES WITH ADVANTAGES

• It is a part of tongue rail fitted with web of tongue rail after stubbing. • It covers those area of tongue rail which is very much prone to wear. It is

about two meter in length from ATS. • Being heat treated, the head of tongue rail causes negligible wear during

service. • Normally tongue rail wear in about two meter length from ATS and rest

of tongue rail has no wear but every time full length of tongue is replaced on account of wear.

• Tongue rail fitted with switch tips need to be replaced the tip portion only and there is no need to replace full tongue rail.

• Worn switch tip after reconditioning may again be fitted on stubbed tongue rails

• The wear pattern observed so for on switch tips are very negligible. • Tongue rail fitted with switch tips will have long service life. Thus will

require lesser consumption of tongue rails as well as lesser frequency of reconditioning of worn tongue rails.

23

• 42 sets of heat treated switch tips for 6400 mm straight switches BG 52 kg were procured in 1990 for wooden layouts and laid on E, SE, C, N, SC, S & W Railways. These switch tips had given service life of 4 to 6 years with negligible wear before replaced by fan shaped PSC switches.

• C. Railway is procuring 90 sets of 10125 mm curved switches fitted with switch tips for BG 60 & 52 kg for PSC layouts through three firms out of which 15 sets have so far been supplied.

• These switches have been laid in suburban section of M umbai division on C. Railway and performance of these switches is satisfactory.

• Other Railways may also procure and lay switch tips after gaining experience by C. Railway.

SPRING SETTING DEVICE

It is a reversible mechanical spring device connected to the foot of two tongue rails at or near JOH. The device actuates after the movement of tongue rails initiated by the point motor reaches about half way. At this stage, one connecting rod of the SSD pulls the open tongue rail away from stock rail and simultaneously the other connecting rod pushes the closed tongue rail firmly against the stock rail. This prevents the rattling of tongue rails between toe and heel under moving wheels and ensures adequate clearance between tongue rails and stock rails. Hence, enhanced life of switches and better riding comfort can be achieved. The Spring Setting Device is used with the turnouts of Voest Alpine of Austria. KRCL has also laid them on turnouts.

EXPLOSIVE HARDENED CMS CROSSING

The initial hardness of CM S Crossing is about 180 BHN while that of cast wheels is 320-340 BHN. By the time, its hardness increases through work hardening, wear ( 2 mm-3 mm ) takes place quickly. ‘Explosive hardening’ process has been developed to overcome this problem. With this process, initial hardness of 350 BHN is achieved. Developmental orders have been placed on two indigenous manufactures to develop this process and supply few such crossings on experimental basis. FAN SHAPED TURNOUTS

On high speed routes, points and crossings on wooden and ST layouts are posing considerable problems in maintenance due to loosening of f ittings, creep, packing not being retained and alignment disturbance. To overcome these problems and for better stability in points and crossings, fan shaped turnouts have been introduced on Indian Railways. Compared to the conventional wooden or steel sleeper layouts, the PSC sleeper layout is much more accurately manufactured and laid into track. Therefore, it is expected to give better riding quality . It has also reduced incidences of signal failures on engineering account.

�

24

� 13.0 DEFICIENCIES OF P & C VIS -À-VIS SOLUTION

In view of recent developments in the field of turnouts on Indian Railways as described above, it has been possible to overcome many deficiencies of conventional turnouts which were serving as impediment for raising speed. The current status of improvements effected vis-à-vis these deficiencies is indicated in the table given below-

Deficiency of Conventional S witch /Crossing

Alternative Designs /Advances

TWIST IN SWITCH PORTION

THICK WEB SWITCHES

OBSTRUCTION BY TIP OF TONGUE RAIL

1 IN 12 HIGH SPEED SWITCH,THICK WEB Sw.

WEAK FASTENINGS T W Sw.,HIGH SPEED Sw.,ELASTIC FASTENING

RAPID WEAR OF TR

HEAT TREATED SWITCHES

INADEQUATE CLEARANCE NEAR JOH (1 IN 12)

SPRING SETTING DEVICE

ANGULAR ENTRY AT TOE

HIGH SPEED Sw.

NON MONOLITHIC CONSTRUCTION OF CROSSING

CMS CROSSING-ORDINARY,EXPLOSIVE HARDENED,WELDABLE

DISCONTINUITY AT CROSSING

MOVEABLE CROSSING

NO 1 IN 20 CANT

NO SUPERELEVATION OVER TR AND LEAD

NO TRANSITION OVER CURVED TR AND LEAD

STRAIGHT CROSSING

25

14.0 PLANS FOR MODERNIS ATION OF TURNOUTS ON IR

CORPORATE SAFETY PLAN

• Fan Shaped Layouts @ 2500 per year.• Thick-Web Switches @ 2000 per year on Group A routes. • Weldable CM S crossings to facilitate continuation of LWRs through

turnouts. (As per correction slip no. 8 to IRPWM, CWR/LWR can be taken through points and crossings in station yards.)

INTEGRATED MODERNISATION PLAN OF IR (2005-2010)

• Adoption of Thick Web Switches.• 10000 to be laid in 5 year period. • Priority : Gr. A Routes and routes with annual GMT exceeding 20. • Provision of weldable CM S crossings to facilitate continuation of LWRs

through turnouts. 15.0 CONCLUS ION

15.1 The 51st TSC had envisaged following permissible speeds on BG turnouts at

various locations - • Turnouts for goods yards to permit TO speed of 25 kmph • Turnouts for passenger yards to permit TO speed of 50 kmph • Turnouts for outskirts of big yards to permit TO speed of 75 kmph • Turnouts at junction between single and double lines to permit TO speed

of 100 kmph This may serve as broad guidelines for enhancing speed over turnouts on Indian Railways. This matter is to finalized in consultation with Operating Department who have to specify and prioritize their requirement of permissible speed on turnouts at various locations.

15.2 An increase in the speed requires not only strengthening of the track but also improvement of maintenance. Following measures may have to ensured- •• MM aacchhiinnee pp aacckkiinngg ooff ttuurrnnoouutt ss lleeeepp eerrss -- AA ss oonn 11--44--0055,, tthheerree aarree tt oott aall

8811006699 ttuurrnnoouutt ss oonn IIRR,, oouutt ooff wwhhiicchh 2244553333 aarree oonn PP SSCC llaayy oouutt ss .. NN uummbbeerr ooff PPSSCC tt uurrnnoouutt ss iiss lliikk eellyy tt oo ggoo uupp iinn nn eeaarr ffuutt uurree && ss pp eeeedd oovveerr tt uurrnnoouutt ss mmaayy aallss oo ww iitt nneess ss aann iinnccrreeaass ee.. IInnccrree aass eedd ss pp eeeeddss mmaayy nneecceessss iitt aatt ee rreedduucceedd ttaammpp iinngg ccyy ccllee.. AA tt pp rreess eenntt ,, wwee hhaavvee oonnllyy 4422 UU NN IIMMAA TT && 99 mmuulltt iippuurrpp ooss ee ttaammpp eerrss ww hhiicchh ddoo nnoott ss eeeemm ttoo bbee aaddeeqquu aatt ee.. AA ddddiittiioonnaall pprrooccuurreemmeenntt ooff mmaacchhiinn ee iinn ll iinnee ww iitt hh rreeqquuiirree mmeenntt ww iillll hhaavv ee tt oo bbee pp llaannnneedd..

• Putting in place a system to ensure better co-ordination between Signal and Engineering Departments.

26

• LWR through Points & Crossings

15.3 Fabrication and assembly of turnouts requires to be done to a very strict tolerances if speeds over turnouts are to be enhanced. PSC fan-shaped turnouts are to be laid into track with the help of cranes only, but these turnouts are still being laid by manual means in field. Due to this, initial laying quality is not of a high standard. As per corporate plan, 2500 PSC fan-shaped turnouts are to laid every year. AAtt pp rreess eenntt ,, ww ee hhaavvee oonnllyy 2255 T-28 machines on IR ww hhiicchh ddoo nnoott sseeeemm tt oo bbee aaddeeqquuaatt ee..

15.4 The turnout is one of the weakest links in the railway track. With increase of

speed upto 140 km/h (at present) and beyond (in future) and increased axle loads, Indian Railways has to go for modern and sturdier turnouts. To cater to these needs, turnouts need to be strengthened so as to reduce recurring maintenance cost. Possible areas of technology up-gradation are given below-

15.4.1 IMPROVEMENT IN GEOMETORY

• Flatter entry angle thereby reducing the angle of attack and reduced lateral forces resulting in increased passenger comfort.

• Adoption of tangential layouts providing benefits of higher speeds. • Introduction of transition curves thereby improving the running

characteristics of the curved tracks. • Use of spring operated switch setting device to ensure proper flange way

clearance. • Use of curved crossings. • Continuation of canting of rails through turnout resulting in smoother r ide

over turnouts. 15.4.2 IMPROVEMENT IN S TRUCTURAL S OUNDNESS Switch Portion

• Use of asymmetrical profile section (ZU-1-60) forged to standard rail profile (UIC 60) at the end.

• Use of higher UTS steel, further hardened to reduced wear. • Effective holding of stock rail with specially designed pins incorporated in

bearing plates. • Use of non greasing eco friendly base plates. • Use of specially designed synthetic rail pads for reduced vibration of

switch assembly. • Housing of switch operating mechanism and detection rods in a hollow

steel sleeper of the size of standard concrete sleeper will be a considerable help in mechanized maintenance.

27

• Provision of thermal restraints to arrest differential thermal expansion of stock and tongue rails.

• Sophisticated pulling techniques including introduction of hydraulic systems.

Crossing Area

• Use of explosive hardened CMS crossing to avoid deformation. • Use of compound crossings with high-manganese steel over running area. • Use of special alloyed steel junction pieces for welding of crossings with

standard rails. • Welded crossings using high grade steel bars (Balfour Beatty design). • Crossings forged and welded from special steel blocks (BWG design). • Surface hardening of load bearing areas. • Use of swing nose crossings, housed in a specially designed cradle.

-------------------------

28

References � Association of American Railroads, Report NO. ER-14, Speed of Trains

Through Turnouts, September 1961 � Railway Research & Engineering News, Section E, Translation Series � Seminar on Points and Crossing, 11.5.81 to 16.5.81, Institute of Advanced

Track Technology, Pune � Design Aspects of M odern Turnouts, K.Santhanam, IPWE(India), RDSO

Centre � Speed on Turnouts, B.P.Agrawal, Indian Railway Institute of Advanced P.

Way Engg. � Speed of Trains on Turnouts, K.V.Rao, Western Railway � IRSAPWE 71st Advanced Course, Development in India to Increase Speed

over Turnouts, Rajendra Rai � Design of Turnouts and Speed on Turnouts by S.J.Singh, M ay1973 � Turnout Design World Practices, August1972 Edition by M . N. Prasad � Modern Design of Points and Crossing,Paper pesented on 5-2-1971, by Y. � Krishna Murty � Turnouts Design and Speeds by K. Santhanam, Paper Presented At Indian

Railway Institute of Advanced P. Way Engg. � Turnouts taken at High Speed by J.N.Lamba � High Speed Turnouts and Its Design Calculation By A.K.Pramannik � Turnout for High Speed by T.R. Natarajan � Developments in India to Increase Speed Over Turnouts by Rajendra Rai � Papers Compiled By Technical Committee, IPWE, M ay 1996

---------------------

Project report by-

i) Sri A.K.Singh, Director/RDSO ii) Sri Jitendra Kumar, Sr. DEN/BPL

29