Rails provide a continuous and level surface for train movement, made from high-carbon steel to withstand various stresses. An ideal rail section must transfer loads efficiently while enduring lateral forces and wear, with specific requirements for jointing and stability. Various types of rails exist, including double-headed, bull-headed, and flat-footed rails, each with their own specifications and failure types such as hogging, kinks, and buckling.

1. Rails

2. Introduction
• Rails are the members of the track laid in two
parallel lines to provide an unchanging,
continuous, and level surface for the
movement of trains. To be able to withstand
stresses, they are made of high-carbon steel.
Standard rail sections, their specifications,
and various types of rail defects are discussed
in this chapter.

3. Function of Rails
• Rails are similar to steel girders. These are
provided to perform the following functions in
a track.
(a) Rails provide a continuous and level surface
for the movement of trains.
(b) Rails provide a pathway which is smooth and
has very little friction. The friction between the
steel wheel and the steel rail is about one-fifth
of the friction between the pneumatic tyre and
a metalled road.

4. (c) Rails serve as a lateral guide for the wheels.
(d) Rails bear the stresses developed due to
vertical loads transmitted to them through
axles and wheels of rolling stock as well as due
to braking and thermal forces.
(e) Rails carry out the function of transmitting
the load to a large area of the formation
through sleepers and the ballast.

5. Requirements of an ideal rail
The main requirements of an ideal rail section are as
under:
(1) The section of the rail should be such that the load of
eh wheels is transferred to the sleepers without
exceeding the permissible stresses.
(2) The section of the rail should be able to withstand the
lateral forces caused due to fast moving trains.
(3) The underside of the head and top of the foot of the
rail section should be of such a slope that the fishplates
fit easly.
(4) The center of gravity of the rail section should
preferably coincide the center of the height of the rail so
that maximum tensile and compressive stresses are
nearly equal.

6. (5) The web of the rail section should be such that it can
safely
bear the vertical load without buckling.
(6) The head of the rail should be sufficiently thick for
adequate margin of vertical wear.
(7) The foot of rail should provide sufficient bearing area on
the underlying sleepers so that the compressive stresses
on the timber sleeper remain within permissible limits.
(8) The section of the rails should be such that the ends of
two adjacent rails can be efficiently jointed with a pair of
fish plates.
(9) The surfaces for rail table and gauge face shouldbe
sufficiently hard to resist the wear.
(10) The contact area between the rail and wheel flange
should be as large as possible to reduce the contact
stresses.

7. (12) The composition of the steel should conform to the
specifications adopted for its manufacture by Open
Hearth of Duplex Process.
(13) The overall height of the rail should be adequate to
provide
sufficient stiffness and strength as a simply supported
beam.
(14) The stiffness of a rail section depends upon the
moment of inertia.The economical design should
provide maximum moment of inertia per unit weigh
of rail with due regard to other factors.
(15) The section modulii of the rail section and that of a
pair of fish plates should be adequate so as to keep
the rail and fish plates within permissible limits.
(16) The foot of the rail should be wide enough so that
therail is stable against overturning.

8. Types of rail sections
• Double headed rails(D.H Rails)
• Bull headed rails(B.H rails)
• Flat footed rails(F.F rails)
In the beginning, the rails used were double
headed(D.H) of a dumb-bell section. The idea
behind using of these rails was that when the
head was worn out in course of time, the rail
can be inverted or reused. But the experience
shows that such indentation are formed in
lower table due to which smooth running over
that surface at the top was impossible.

9. Double headed rails:
• These were the rails which were used in the beginning,
which were double headed and consisting of a dumb-
bell section.
• The idea behind using these rails was that when the
head was worn out in course of time, the rail can be
inverted and reused.
• But as time passed indentations were formed in the
lower table due to which smooth running over the
surface at the top was impossible.

10. Bull headed rails:
 In this type of rail the head was made a little thicker
and stronger than the lower part by adding more
metal to it, so that it can withstand the stresses.

11. Flat footed rails:
• These rails are also called as vignole's rails.
• Initially the flat footed rails were fixed to the
sleepers directly and no chairs and keys were
required.
• Later on due to heavy train loads problems arose
which lead to steel bearing plates between the
sleeper and the rail. at rail joints and other
important places these are the rails which are
most commonly used in india.

12. Factors governing length of rails:-
• Manufacturing cost
• Transportation facility
• Lifting and handling operation

16. Failures in Rails

17. • Hogged rails: due to battering action of
wheels over the end of rails, the rail get bent
down and deflected at the ends, this hogging
is due to loose packing under the joint and/or
loose fish plate. Can be removed by
Cropping, replacing, welding and dehogging.

18. • Kinks in rails: when the ends of adjoining rails
move slightly out of position “kinks” are formed.
Kinks formed due to loose packing at joints,
defects in gauge, and alignment, defects in cross
level at joints, uneven wear of rail head, where
kinks are formed at joints .

19. • Buckling of rails: buckling means track has
gone out of its original position or alignment
due to prevention of expansion of rails in hot
weather on account of temperature
variations. Causes are following
I. When expansion gap is not sufficient
II. The fish plate are bolted so tight that no slip
is allowed.
III. Due to presence of longer welded rail on
weak tracks.

20. Buckling of rails

21. Wear on rails
• Wear is one of the prominent defects of rails.
Due to heavy loads concentrated stresses
exceeds the elastic limit resulting in metal
flow; on the gap or joints the ends are
battered and at the curves the occurrence of
skidding, slipping and striking of wheel flanges
with rails results in wear and tear on rails.

22. Classification of wear
• On the basis of location
I. On sharp curves
II. On gradients
III. On approach to stations
IV. In coastal area etc.
• On the basis position of wear
I. On the top of rail
II. At the end of rail
III. on the sides of the head

23. Burr: a rough edge or
ridge left on an object
(especially of metal) by
the action of a tool or
machine.

24. Methods to reduce wear
• When wear exceeds the permissible limit (5 %
of the total weight section) the rail must be
replaced.
• Use of special alloy steel at the location where
wear is more.
• Reduction in number of joints by welding
• Regular tightening of fish bolts and packing of
ballasts.
• Welding and dehogging of battered ends in
time also the solution for wear.

25. • Maintenance of correct gauge will reduce the
side wear in particular.
• Lubricating of the gauge face of outer rail on
curve, will also reduce the wear.
• Interchanging of inner and outer rails and
changing face at curve will reduce the wear.
• Application of heavy mineral oil, in case of
corrosion of rail metal under adverse
atmospheric conditions, reduce the wear of
rail.