Project on Review of

Various types of SEJs under trial on Indian Railways

submitted by

B.L.Meena,Dy.CE/SOR & IT,SECR &

M.V.Chalapathi Rao,XEN/CN/SWR

Review of various types of SEJs under trial on Indian Railways

INTRODUCTION-

The IRS design of Switch Expansion Joints have been in

service on Indian Railways since 1960s. However, there

have been several cases of fractures reported on the

stock/tongue rails of the standard SEJs since 1990. Such

sudden and unpredictable fractures in running tracks

obviously pose a safety hazard. A study of the reasons for

such failures and the possible remedial solutions is

considered necessary

At the time of initial introduction of IRS design of SEJs during

1960s, the rails used were Medium Manganese type having

ultimate tensile strength (UTS) of 72 Kg/mm² and percent

elongation of 14% (min). Due to significant increase in rail life

with the use of higher UTS rails, Indian Railways have been

using rails with UTS of 90 Kg/mm² since late 1980s.The

percent elongation of these new rails is only 10% (min).

Further, the high UTS rails are highly sensitive to bends, nick

marks etc., which are normally caused at the time of

handling/ machining of SEJs. Consequently there have been

several fractures of stock / tongue rails of IRS design of

SEJs manufactured from high UTS rails as compared to

almost nil fracture earlier.

Switch Expansion Joint :

Switch Expansion joints are provided on either end of Long

Welded Rails to allow expansion and contraction due to

thermal stresses developed in it.

Improvements in design :

1. To avoid two bends involved in the design of the stock rail

and tongue rail in conventional type of SEJ.

2. To avoid fractures in the bent portion of stock rail and tongue

rail in conventional type of SEJ.

3. To meet other requirements like wide gap at bridge

approaches.

4. Suitability in curves sharper than 0.5º and up to 4º.

5. Suitability for higher axle loads

6 for iron ore route

7 for heavy mineral route

8. Suitability for high speed routes.

SEJs under trial :

1. SEJ with 80mm gap on concrete sleepers

• for 52kg( Drg. No. RDSO/T-4160 )

• for 60kg ( Drg.No. RDSO/T-4165 )

2. SEJ with 60kg UIC on curve with curvature from 0.5º to 1.5º

(Drg.No. RDSO/T-5748)

3. SEJ with 190mm gap for bridge approaches.

for 52kg ( Drg. No. RDSO/T-6039 )

for 60kg ( Drg. No. RDSO/T-6263 )

4. SEJ for 80mm gap with CR-120 crane rails (Drg.No.

RDSO/T-6257)

5. SEJ with one gap

developed by M/s Rahee Industries Ltd, Calcutta.

6. SEJ with two gaps

developed by M/s Bina Metalway, Jamshedpur. &

M/s Chintuparni Engg. Works, Barabanki.

Review of SEJ with 80 mm gap :

RDSO/T-4160 and RDSO/T-4165 are the conventional

straight SEJs with 80 mm gap. Each SEJ has a pair of

tongue rails stock rails, with 6 special sleepers to RDSO

drawing No.RDSO/T-4149.All these are 300 mm wide

sleepers with sleeper Nos 10 and 11 with special fastenings

and sleeper No. 8,9,12 and 13 with similar fittings. The

center line of sleeper No. 10 coincide with the tip of the

tongue rail and the 40 mm initial gap is provided with tip of

the tongue rail coinciding with the center of the sleeper

No.10. The center to center spacing of sleeper No. 10 and

11 is 700 mm while the sleepers spacing from 1 to 10 and 11

to 20 may be 600 mm or 650 mm depending upon the

sleeper density.Fig.No.1 gives details of a typical SEJ layout

and Fig.No.1(a) gives the details of location A.

SEJ on curves with curvature from 0.5º to 1.5º :

These SEJ layouts can be used when the SEJ has to be laid

in a curve sharper than 0.5º but not sharper than 1.5º. The

tongue rail and stock rail are given curvature as shown in

Fig.No.2

The conventional SEJ design involves two bends in the stock

rail and tongue rail which are locations of weakness

resulting in fractures. Improved design SEJs developed by

various industries are under trial on the Railways till the

approval is received from the Railway Board.

Curvature details are given below

Fig.No.2

SEJ with 190 mm gap for bridge approaches :

These are wide gap SEJs for bridge approaches where

maximum gap permitted is 190 mm, the mean position is

kept at 166 mm from center line of sleeper No. 10 to enable

the tongue rail to remain on the sleeper even when the entire

expansion takes place. Sleeper No.7, 8, 9, 10, 11, 12, 13 are

special sleepers with sleeper Nos 9,10 and 11 with special

fastenings. Use is made of ERC mark II clips with flat toe

designed with a toe load of 350 to 400 Kg/ clip to enable free

rail movement. Sleepers other than 7 to 13 are approach

concrete sleepers with normal fittings. When the gap is more

than 100 mm for passing dip lorries with smaller diameter,

use of an insertion piece in the gap should be made.

Review of SEJ with one gap :

This design has been developed by M/s Rahee Industries

Ltd,Calcutta. Fig.3.6 the design comprises of a pair of

machined segments on non gauge face side of two non bent

running rails mounted with a gap between the juxtaposed rail

ends and the third rail called a gap avoiding rail of

predetermined length accommodated in the said machined

segments parallel to and adjacent to the non bent straight

length of the running rails. This rail is securely fitted to one of

the running rails with high tensile steel bolts. This running rail

together with the gap avoiding rail is called the stock rail. The

other running rail is called the tongue rail. The non bolted

segment of the gap avoiding rail braces the machined

segment of the tongue rail. It provides an elbow-free

arrangement without any stress-raising bends. The lap joint

is provided by a bolted-on stock rail. There are no short rails

and every rail piece is long enough to resist the longitudinal

forces from trains.

There are no bends either hot or cold in the Rahee design.

Rahee SEJ does not utilise a floating length of short rail. The

risk of inadequacy of its longitudinal resistance against creep

forces stands eliminated. The width of the rail head is

increased to 90mm over the transfer length. This ensures

adequate bearing. The wheel tread does not jump the gap

but is smoothly guided into the rail which is wide enough to

give the outer half of the full support.

The Rahee expansion joint permits expansion up to 200 mm

normally and more with modification. There is no risk of rail

fracture or cracks as there are no bends or stress raisers.

The principle of the “Baton passing” has been incorporated in

the Rahee SEJ Design. As the wheel swings from side to

side in its natural sinusoidal motion, possibility exists of the

root radius grazing the rail ends. This is eliminated by the

use of a check raill which pushes the wheel gently on to.

The purpose of the check rail is only to ensure a smooth

transfer of the wheel from rail to rail. It can be removed for tie

tamping work etc. without any detriment to safety or affecting

traffic in any way.

The Rahee Switch Expansion Joint system has been

standardized by the World bank consultants M/s Canarail /

Systra for the Jamuna bridge rail link project in Bangladesh.

SEJ with one gap developed by Rahee

Advantages of SEJ with one gap :

1. No bends in tongue and stock rail.

2. Only 5 sleepers of standard SEJ on PSC assembly are used.

3. Check rails guard against excessive play of worn out

wheels.

4. Design suitable up to 200mm max. gap.

Review of SEJ with two gaps :

Two designs have been developed by two different firms

(M/s Bina Metalway, Jamshedpur and M/s Chintpurni

Engineering Works,Barabanki). In both these designs two

gaps of maximum 80 mm each are provided in one SEJ.

Thus a maximum gap of 80 mm is available for an LWR on

one side of the SEJ. Similarly a gap of 80mm is available for

the LWR on the other side. The tongue rail is manufactured

by cutting the rail at head and foot location. Two cut rails are

joined together to make the stock rail.

Salient features of Bina Metalway 2-gap SEJ

The stock rail is considered to be static with negligible

expansion and contraction in length due to temperature

changes. This SEJ makes use of 6 wider concrete sleepers

each to Drg No. T/4149, with three sleepers located near

each gap. The length of the SEJ is 5750 + 6950 + 5920 + 80

= 18700 mm.

Hence a total gap of 18750 mm should be created while

inserting this SEJ. The stock rail is fabricated out of two

pieces of lengths 7140 mm and 5920 mm connected to each

other by HTS bolts. While laying the SEJ it should be

ensured that the ends of the stock rail are 40 mm away from

the centre line of sleeper Nos. 12 and 22 with the tip of the

tongue rail coinciding with the centre line of the sleeper.

1. Sleeper Nos. 1 to 31 should be at a spacing of 600 mm c/c.

2. Sleeper Nos. 10' 11 I 12, 22, 23 and 24 are special sleepers

to RDSO drawing No. T -4149 and the rest are normal PSC

line sleepers.

3. Mean position of SEJ should be kept at centre line of

sleepers No.12 and 22.

4. The mean gap is 40 mm on each end.

5. The tongue rails are kept at mean position at centre line of

sleeper Nos. 12 and 22, and stock rail end kept at 40 mm

from mean position, thus creating a gap of 40 mm.

6. The mean position should also be marked on the rail posts

erected on both sides of track.

Salient features :

BENDS IN STOCK / TONGUE RAILS:

The IRS design of SEJs make use of stock and tongue rails

which have two sharp bends of more than 7º in close

proximity. The high UTS rails being highly sensitive to such

severe bends proneness to sudden fractures at the bends is

to be expected.

NUMBER OF GAPS AND NOMINAL GAP VALUE:

The conventional SEJ uses one gap of 40mm nominal size

between stock and tongue rails. Under temperature changes,

this gap can vary from 28 to 74 mm as per the Tables at

Annexure -V of LWR Manual (1996).

MINIMUM HEAD WIDTH OF RAIL :

In IRS design of SEJ, the maximum head width of tongue rail

is only 35% of full rail head width. As such, the rate of wear

of rail in such cases becomes high.

M/s. Bina Metal Way Ltd., who have been in the service of

Indian Railways since early 1980s, have studied the

problems experienced in the use of conventional SEJs and

have developed an improved design of SEJ. Fig. 4 shows

the salient features of BMW's design. The patented features

of BMW's design of improved SEJ vis-a-vis the features of

IRS designs of SEJs are compared in the following

paragraphs.

BEND-FREE STOCK / TONGUE RAILS :

In the Improved design of SEJ, there are no bends either in

stock or tongue rail. In order to achieve this feature, the stock

rail is fabricated by machine and bolting together two

separate rails. However the tongue rail is similar to tongue

rail of conventionall SEJ, except that there is no bend in the

rail.

NUMBER OF GAPS AND NOMINAL GAP VALUE:

An advantageous feature of the improved SEJ is provision of

two gaps each of 40 mm (nominal) size each between the

centrall stock rail and the two adjacent tongue rails. Due to

temperature changes in welded rail, each of the gaps of 40

mm nominal size is expected to vary from 33 to 57 mm in

Zone IV. The 57 mm (max) gap is expected to lead to lesser

impact under passing wheels as compared to that under the

maximum gap of 74mm in IRS type of SEJ.

Another advantage accruing from the use of two gaps at

each SEJ is that it gives the PWI better control in providing

correct nominal gap at the time of installation / replacement

of SEJs. Providing a single nominal gap of 40mm between

the ends of LWR poses severe difficulties for the field staff

considering working conditions at site. Since a nominal gap

of less than 40mm can eventually cause problems by way of

buckling of track, the PWI consciously tries to avoid chances

of buckling by providing a larger initial gap. This is one of the

prime reasons for the large gaps normally observed in

conventional SEJs even at the height of summer.

MINIMUM HEAD WIDTH OF RAIL :

In BMW's design of SEJ, the minimum head width of tongue

rail is more than 61% of the full rail head width. This is in

contrast to the 35% head width in conventional SEJs. As

such, lesser wear and longer life can be expected from the

new design.

PEARLITISING OF RAIL HEAD :

The wear prone areas of stock and tongue rails are

pearlitised by through a special process to achieve a

hardness of 320 BHN. This has been found to significantly

increase the wear life of rail heads at the critical gap zones.

PERFORMANCE OF SEJs OF M/s. BMW MAKE

Several Railways, namely Central, Eastern, Northern, South

Central, South Eastern and Western Railways have procured

over 850 Nos. of Improved SEJs from BMW based on the

recommendations of 69th Meeting of TSC held at Puri in

January 1998. (This quantity includes 100 Nos. ordered by

Railway Board for supply to Eastern and Northern Railways).

Out of these, over 650 sets have already been laid in track

as per the information available with BMW. As the design is

new, BMW interacts closely with field-staff for trouble-

shooting and for constant up-gradation of design. The

performance of the SEJs has been reported to be

satisfactory.

Review of USE OF BMW'S SEJ ON CURVES:

As per para 3.2.1 of LWR Manual, LWR shall not be laid on

curves sharper than 440m. Again, as per para 4.5.5 of the

Manual, SEJs with straight tongue / stock rails shall not be

located on curves sharper than 0.5° as far as possible.

Consequently, the above two stipulations read together,

prohibit the use of SEJs on a large number of curves. To

remedy this situation, BMW is in a position to supply SEJs

with pre-curved stock rails to suit curves in steps of 1°, 1.5°,

2°, 2.5°, 3°, 3.5° & 4° (440m) as shown in Fig. 5. Such pre-

curving is suggested due to the reason that the stock rail in

BMW's design is of rigid construction (being made of two rail-

webs bolted together). Therefore, BMW proposes to pre-

curve the two rails (forming part) of each stock rail, bolt them

together and supply such stock rails as part of curved SEJs

ordered by the Purchasers.

The tongue rail, being slender, can be curved at site by the

PWI using a jim-crow. Or else the tongue rail can even be

used without pre-curving, as is the normal practice with use

of rails in curves, turnouts etc where the rail-sleeper

fastenings assist the PWI in achieving the requisite

curvature. This suggestion is being made as curved tongue

rails, if consigned by BMW, are likely to get distorted in

transit / unloading etc requiring correction of curvature at

site.

The procurement of some curved SEJs as per Fig. 5 (with

pre-curved stock rails) by the Railways as part of normal

SEJs ordered by them from BMW and their trial use on

curved tracks will thus help Indian Railways to standardise

the use SEJs on curved tracks up to 4°, instead of restricting

their use to curves up to 0.5° as per present stipulations of

LWR Manual. It is to be emphasised that the stock rail used

in BMW's design of Improved SEJ has a sturdier cross-

section as compared to that of IRS design of SEJ. Similarly,

the tongue rail in BMW's design of SEJ has no bend unlike

the tongue rail of IRS design of SEJ. Both these features

enable achieving a safer pre-curved SEJ for use in curved

LWR tracks.

No. of SEJs manufactured,supplied are 865 sets

DIFFERENCE IN FEATURES BETWEEN IRS SEJ AND BMWs SEJ

SL.NO FEATURES IRS DESIGN BWM DESIGN ADVANTAGES

1 BEND IN RAILS 7 DEG 7 MIN NO BEND No breakage

2 SLEEPER SPACING 650 & 700 mm 600 mm Min. packing

3 NUMBER OF GAPS 1 2 Easy maintanance

4 Max.GAP 120 mm 65 mm Less wheel impact

5 Head thickness of ton.rail 25.5 mm 44.75 mm Increases life

6 Head thickness of St.rail 72 mm 89.5 mm More wheel support

7 Status of stock rail moving static Room to LWR forexpansn

8 Pearlitising of rail head Not specified Pearlitised Reduces wear

9 Use on curves Limited to 0.5º Up to 4º Scope for use

Fig.No.4

Advantages of two gap SEJ 1. The maximum gap is 57 mm which lead to lesser impact

under passing wheels as compared to gap of 74 mm in IRS

type.

2. It gives the field staff better control in providing correct

nominall gap at the time of installation/ replacement of SEJ.

3. The minimum head width of tongue rail is more than 61% of

full rail head width (44.75mm) as against 35% of head width

(25.5mm) in conventional type.

4. The wear prone areas of heads of stock and tongue rails are

pearlitised through a special process to achieve a hardness

of 320 BHN

5. Maximum head thickness of stock rail is 89.5 mm as

compared to 72 mm in IRS type of SEJ which in turn

increases wheel support.

6. Status of stock rail is static as compared to moving type in

IRS type of SEJ.

7. It is suitable to be laid in curves in steps of 1º,

1.5º,2º,2.5º,3º,3.5º,4º by supplying pre curved stock rails.

8. The tongue rail being slender can be curved at site by the

field staff.

Suggestions :

1. German Railways are not at all using SEJs.

2. Even distressing is not required.

3. It will be worth while to study laying and maintenance of

LWR in German Railways with improved elastic fastenings,

breathing lengths can be brought down eliminating SEJ.

4. The range of temperature is also from –25º to +65º ie 90º

variation.

5. Once methods for finding stress free temperature of LWR

are developed, SEJ as well as distressing can be dispensed

with in India also.

6. Delhi Metro Railway has used wide gap SEJ of 300 mm

7. Indian Railways has used 300 mm wide gap special type of

SEJ in Jammu – Udhampur section

References

1. LWR Manual 2. RDSO publications 3. The design developed by M/s Rahee Industries

Ltd,Calcutta.

4. The design developed by M/s Bina Metal

ways,Jamshedpur and M/s Chintuparni Engineering

Works, Barabanki.

Fig.No.4( a ) SEJ with two gap developed by Bina Metal Way

Fig.No.5

Fig.No.1(a)

Fig.No. 4(b)

Fig.No.1 Switch Expansion Joint