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CONTENTS

DEFINATION Components of slab track Types of slab track Advantages Conclusion

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DEFINITION

SLAB TRACK IS DEFINED AS A TYPE OF TRACK WHERE THE SLEEPERS AND BALLAST ARE REPLACED BY A CONCRETE OR ASHPHALT LAYER.

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HISTORY OF SLAB TRACK

In the late 20th Century slab track started to appear, especially in tunnels, where the floor of the tunnel would be a single slab of concrete in two layers, with the rail attached to fixtures in the second layer. The first layer would seal the floor from water, and attain a profile of approximately the right dimensions. The second layer would be laid to a greater degree of precision.

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Problems in ballast track

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Problems in ballast track

Slow deterioration of the ballast material due to traffic loading

wear & tear of ballast causes geometrical unevenness & clogging leads to drainage problems

Frequent maintenance of track alignment is needed

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Problems in ballast track

Wear and tear creep of rail

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Need of slab track

Very low dynamic stiffness

Reduces vibration and noise significantly

All components are easily replaced

Longitudinal creep resistance can be adjusted

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comparison

Slab trackLess noiseFor high speed railsLonger service lifeLess maintenance

Ballast trackMore noiseFor low speed railsLesser service lifeHeavy maintenance

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Components of slab track

Base plate assembly

Cast in shoulder assembly

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COMPONENTS OF SLAB TRACK

Rubber wedges which support the rail at the web Side support brackets which hold these in place and transfer load to the support structure locking wedges, which fix the side bracketsShoulders which provide location and the reaction point against which the fastening is braced

FUNCTIONS

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CONSTRUCTION OF SLAB TRACK

Subgrade soil:   PI =5.9

LL = 18.5

moisture content =5 to 12 %

OMC = 10.5%

The modulus of the soil is > 10,000 psi Compressive strength

> 50 psi.

Figure :The final prepared sub grade surface. 14

Subbase

The subbase is a 6-inch soil cement layer (5%)

Compacted at an optimum moisture content of 12.5%

Compaction is specified to be 98 percent

The target compressive strength is 700 psi

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Fig : sub base with soil cement layer Fig: Compaction of sub base with soil cement layer

Fig : sub base with soil cement layer Fig: Compaction of sub base with soil cement layer

Fig: Final surface of the soil cement layer.

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METHODS OF LAYING SLAB TRACK

Two methods

1.Direction Fixation Slab Track (DFST)

2.Independent Dual Block Track (IDBT)

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Direction Fixation Slab Track (DFST) Slab is 1 foot thick

10 feet 6 inches wide & 5,000 psi

Track resilience and damping are provided primarily through the rubber pads installed between the fastener plates and the slab surface.

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Independent Dual Block Track

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Independent Dual Block TrackSlab is 7.75-inch-thick reinforced bottom

concrete slab

10 feet 6 inches wide and 5,000 psi

Track resilience and damping were provided

primarily through the rubber boots as well as the pads installed inside rubber boots.

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conclusion Concrete slab track is constructed

particularly for high-speed rails Soil pressures are evenly distributed under slab track Slab track can maintain high-speed

track geometry while being subjected to heavy axle loads

The track modulus of slab track is much more uniform than for ballast track

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