STANDARDS AND SPECIFICATIONS IN RAILWAY TRACK

3.1 Specification of Rail Section

The rail is designated by its weight per unit length. In FPS units, it is the weight in lbs per yard and in metric units it is in kg per metre. A 52 kg/m rail denotes that it has a weight of 52 kg per metre.

The weight of a rail and its section is decided after considerations such as the following:

• Heaviest axle load
• Maximum permissible speed
• Depth of ballast cushion
• Type and spacing of sleepers
• Other miscellaneous factors

The standard rail sections in use on Indian Railways are 60 kg, 52 kg, 90 R, 75 R, 60 R and 50 R. The two heavier rail sections, 60 kg and 52 kg, were recently introduced and are designated in metric units. Other rails are designed as per the revised British Standard specifications and are designated in FPS units though their dimensions and weight are now in metric units. In the nomenclature 90 R, 75 R, etc., where R stands for revised British specifications.

UIC—International Union of Railways

IRS —Indian Railway Standard

RBS—Revised British Standard.

3.1.1 Details of Standard Rail Section:

1. IRS -52 Kg/m

2. UIC -60 kg/m

3.2 Specifications for sleepers

The concrete sleeper of railway track are of priestess concrete having a crushing strength of 550 kg/sq.cm and have reinforcement in the form of tensioning wire/strand inside it. Sleeper may be of pre-tensioned or post-tensioned priestess concrete confirming to Indian Railway design. The dimensional details of concrete sleepers are given below for information:

i. Dimensions

• Length : 2750 mm
• Width-Top (at centre) : 154 mm
• Width-Bottom (at centre) : 220 mm
• Height (at centre) : 180 mm

ii. Reinforcement : 18 nos., 3x3 mm dia. strands

iii. Weight : 267 Kg

iv. Service Life : 50 to 60 years.

Design features

• Initial prestressing force = 37 t
• Final prestressing force = 31 t
• Minimum concrete strength in 28 days = 550 kg/cm2
• Minimum strength of concrete at the time of applying prestress = 450 kg/cm2

Indian Railways is modernizing its track in a big way to meet the challenges of heavier traffic at faster speeds. The modern track consisting of long welded 52-kg/60-kg rails, concrete sleepers, and elastic fastenings can meet the above requirements. Prestressed concrete sleepers are most economical and technically best suited for high speeds and heavy traffic density. They provide a stable track structure, which requires less maintenance efforts. Maintenance of concrete sleepers track should, however, be done using track machines only.

It has been proposed that concrete sleepers should be provided on all important routes of Indian Railways. Adequate capacity has been developed for the production of these sleepers to meet all the requirements of IR. During 2003–04, 8.86 million concrete line sleepers (highest ever production) and 3426 sets of concrete turnout sleepers were produced. The intake of wooden sleepers for main lines has been completely stopped and emphasis is being laid on using concrete sleepers on turnouts.

Indian Railways is the world leader in the manufacture of concrete sleepers and is presently manufacturing about 60% of the total concrete sleepers in the world.

These concrete sleepers have a very bright future on Indian Railways.

3.3 Specifications of track ballast

Basic Quality:

Ballast should be hard durable and as far as possible angular along edges/corners, free from weathered portions of parent rock, organic impurities and inorganic residues.

Particle shape:

Ballast should be cubical in shape as far as possible. Individual pieces should not be flaky and should have generally flat faces with not more than two rounded/ sub rounded faces.

Physical Property

Ballast sample should satisfy the following physical properties in accordance with IS: 2386 Pt.IV-1963 when tested as per the procedure given in Annexure-I & II.

Ballast should satisfy the following size and gradation:

• Retained on 65mm Sq.mesh sieve 5% Maximum
• Retained on 40mm Sq.mesh sieve* 40%-60%
• Retained on 20mm Sq.mesh sieve Not less than 98% for machine crushed

Not less than 95% for hand broken

* For machine crushed ballast only.