PRESENTATION ON

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� Irregular Settlement � Defects at special track Positions – P&C, joints,

SEJ, LC’s� Damage of Ballast at places with irregularities

eg. Rail defects, welded joints, insulating rail joints, bridge approaches.

� Track maintenance after 30-60 million tonnes / after track has settled about 20 mm

� Deep screening after 10 years � Complete ballast renewal after 30 years.

PRIME REASONS

� High frequency vibrations� Uneven settlements

FIG. 1

DISPERSION OF CONTACT STRESSES

1.210100Ballast-Formation

52380Sleeper-Ballast

25510Bearing Plate-sleeper

62200Rail-Bearing Plate

42003Rail- Wheel (25 t -axle load)

Pressure (kg/cm2)

Area (cm2)Location

TRACK MODULUS FOR DIFFERENT TYPES OF SOIL

150-200250-300Concrete bottom /stone/rock

100-150150-200Very good gravel/rock

80-100100Good course sand/gravel 5050Poor soft to rigid

2020Very Poor fine grained MoorumBallast

Track Modulus N/cm3Soil Type

DESIRABLE CHARACTERISTICS

� Rail settlement > 1.2 mm

� Track Modulus ≤ 0.1 N/mm2

� Rail foot tension ≤ 60 N/mm2

FUTURE SCENARIO

� Quarrying may be banned� Long lead –cost implications� Restrictions on maintenance time

� Technological development and research in Railway track construction has lead to introduction of BLT usually referred as slab track. This system was first introduced in Japan in late 60’s.

BALLAST LESS TRACK (BLT)

A VIEW OF BLT ON ELEVATED TRACK

FIG. - 4

� ADVANTAGES� Reduced maintenance cost� Reduced traffic blocks� Low structure height� Dust free � Road rescue vehicles can ply over BLT in

tunnels

ADVANTAGES & DISADVANTAGES

� DISADVANTAGES� Requires high precision laying by automated

machines� Expert supervision� High cost of construction- about 1.5 to 2 times

over the conventional Ballasted track.� Derailments can cause costly damage� Repair work is more complicated� Increase in noise level

ADVANTAGES & DISADVANTAGES

� Firm formation (Normally used in tunnels)� Investigate upto 6m depth, every 50m� Upto 2.5m below, in normal case and upto 4m

in clay soils- earthwork of designed Qlty� Take care in deep cuttings� Compaction of Highest quality� Formation profile +/- 2mm� Hydraulically Bonded layer-300mm� On formation –additional cost 2 to 2.5 times

ESSENTIALS FOR BLT SYSTEM

� Efficient drainage in tunnels � Design for Piezometric head� Transitions to be designed� Advance planning for signaling and track

circuiting.

ESSENTIALS FOR BLT SYSTEM

IMPORTANT ISSUES

� Expected life 50-60 years� Not preferred in Earth quake areas� Alteration in geometry not possible

� Fixed cant values� Fixed curvature and transitions

DEFECTS DUE TO WATER INGRESS

DAMAGE TO POLYSULPHIDE

WATER OOZING FROM BOTTOM

TYPES OF SLAB TRACK

� Rheda- ----continous sleeper trough� Rheda-Berlin—twin block with

untensioned reinforcement� Rheda-2000—Modified twin block

sleeper with braced girder reinforcement� Heitkamp Design- concrete trough gravel

filling � Zublin Design- 10 sleepers inserted into

unset concrete

TYPES OF SLAB TRACK

� Laid-on design- slab track on asphalt � SATO design� FFYS design� ATD design-� BTD design� GETRAC design� Lawn slab Track- two beams, central

grass

TYPES OF SLAB TRACK

� FFC design-Concrete sleeper of � length� Bogl design� OBB-Porr design� Plate track in Japan (Shinkansen)� INFUNDO design- Rail sealed in synthetic

material� SFF design –longitudinal sleeper� SAARGUMMI design

BLT SYSTEMS IN USE AROUND THE WORLD

BLT SYSTEMS

Support @ discrete points Embeded Rail Structure

Netherland

BLT SYSTEMS

Support @ discrete points

Twin Block (bi-block system) Monoblock System

Cast –in- situ Prestressed monoblock sleepers into pretensioned slab

BLT SYSTEMS

Cast- in- situ

StedefFrance

SonnevilleFrance

ShinkansenJapan

Edilon blockNetherland Swisswalo

RhedaGermany

ZubinGermany

Prefabricated Germany

BLT SYSTEMS

RhedaGermany

Rheda 2000 Rheda Berlin RhedaRathenow ATD GETRACA 1

BLT SYSTEMS

Prestressedmonoblock

sleepersembeded

in to pretensioned slab

OBB-PorrAustria

PorrAustria

ZublinGermany

BLT SYSTEMS

Embeded RailStructure

Low Noise SA 42BB

EmbededRail

ERIA (EmbededRail in Asphalt

FIG.- 3

FEATURES OF SHINKANSEN SLAB TRACK (JAPAN)

� Size of Slab: 4.93X2.34X0.19/ 0.16 � Cylindrical Stopper: To restrict longitudinal

and lateral movement� Sleeper blocks kept in position with rubber pad

below and side and grouted to concrete bed.� Blocks are fixed over deck slab having required

cantt.

FEATURES OF GERMAN SLAB TRACK

� 15 cm reinforced bed.� 20 cm light concrete� 14 cm, M35 concrete� Concrete sleeper embedded grouted � 10mm rod passes through 3 cm dia. hole

horizontally.

A VIEW OF BLT

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FEATURES OF BLT ON KONKAN RAILWAY

� Total length 22 km on Roha-Mangalore Section.� Existing PSC sleeper are embedded into the

concrete bed. � Rubber pad below sleeper.� Polyethylene Foam used around the sleeper.

FASTENINGS OF SLAB TRACK

� Insulation & resilience GRP under rail seat � Microcellular pad below bearing plates� Steel clips/ Liners with insulation coating� Anchor bolts � Hole in slab for fixing inserts with epoxy � 2 stages of resilience.� Resilient pad below sleeper block� CAM under Concrete slabs (Japan)

GENERAL METHOD OF CONSTRUCTION

� Sleeper cast into concrete slab� In embedded sleeper - cast into slab, rubber

boots provided for elasticity � Special slip form paver lay concrete slab

following which sleeper fitted with pads position and cast in suite

� OBB-Porr, monoblock sleeper enclosed in rubber are cast in prefabricated slab.

� In top-down system place rails & lock first in position and casting using corkelast to provide elasticity

BLT SYSTEMS IN USE IN DIFFERENT COUNTRY

Germany, Netherland, Tyavan, Spain, Bretain,DMRC,SR

1993-2006

160-350270++Rheda Family 2

1964

Year of Laying

Tokyo, S.Koria & Rome

350 km1010 (D/L)

Shinkansen(Japan)

1

Country Speed Potential

KMName of System

Sr.No

DEVELOPMENT IN INDIA

� Introduction of BLT in India started decades back, first by Calcutta Metro followed by Konkan Railway, Chennai Metro and Delhi Metro.

� The scope for development of the system is very large due to future development planned for Mumbai Metro, Bangalore Metro and introduction of high speed Routes.

� Technological innovation is therefore a must to accomplish the task of above mentioned Metro Systems.

FIG - 2

FIXED DIMEN SION

A

A

A

SHEAR CONNECTORIN VER T LINING

KERB CONCRETE

C.L. OF TUNNEL & TRACK

FINISHED LINE

OVER T LINING

MINIMUM EXCAVATION L INE

DR AIN

RAIL TOP

STEEL RIBS ISHB 150 X 150 @ 34.6 KG /M

100 MM TH. SH OTCRETE WITH WIR E MESH

FUTURE DEVELOPMENT� Modified form of KRCL earlier design/development. � Based on indigenous fittings� Embedded systems/� Slab system� Top down construction

FASTENINGS

� BEARING PLATE AND ANCHOR BOLTS� ELATOMERIC PADS� ELASTIC FITTINGS� INSULATIONS� SHEAR CONNECTOR

WORK IN PROGRESS-MTP

PERFORATED PLATE

FIG.- 5

BALLASTLESS TRACK

RAIL TOP

DRAIN

STEEL RIBS ISHB 150 X 150 @ 34.6 KG /M

100 MM TH. SHOTCRETE WITH WIRE MESH

OVERT LINING

C.L. OF TUNNEL

MINIMUM EXCAVATION LINE

FINISHED LINE

300mm THICK LININGSTEEL RIBS ISHB 150 X 150 @ 34.6 KG /M

LEVEL LING COURSE 1:3:6

NEED FOR MAINTENANCE MANUAL

� Check of wear on fastenings.� Level and gauge� Rail defects� Concrete slab defects

CONCLUSION

� An effort should be made in the right earnest to develop future BLT for mass utilization for the construction in Indian Railways with high precision accuracy by automated machines which infact can save lot of Foreign Exchange revenues.

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