WORKSHEET 6
Name: COMPETENTE, JOHN ANGELO C. Course/Year: BSCE- 3A
1. What do you understand by a railway track or a permanent way? Mention the
requirements of an ideal permanent way.
- The permanent route should be correctly planned so that the train's load is
evenly distributed between the two tracks. The track's lateral strength should be
enough. Curves' radii and superelevation should be correctly planned. A certain
level of flexibility is required for the track.
2. What are the component parts of a permanent way?
- The following are the elements of a permanent path. I Sub-grade or formation (ii)
Ballast (iii) Sleepers (iv) Rails (v) Fixture and Fastening Rails are permanently
linked either by welding or by utilizing fish plates and are secured to sleepers
using various types of fasteners.
3. Draw a typical cross section of a BG double track in embankment and show
therein all the components of the track.
4. What is meant by ‘track modulus’? Indicate its usual range of values for a broad-
gauge track.
- The vertical rigidity of the rail foundation is measured by track modulus. Track
stiffness is another characteristic that measures the vertical rigidity of the
complete track system. Both are associated with track performance.
5. How is track modulus expressed? State the factors affecting it and give the
values of at least one of these factors for the tracks in our country.
- Track modulus is a measurement of the vertical stiffness of the rail foundation,
whereas track stiffness is the overall stiffness of the track system. The impact of
subgrade soil conditions on track modulus and stiffness is demonstrated to be
the largest. The combined ballast-subballast thickness and vertical tie-fastener
rigidity are the next most important factors.
6. Draw a typical cross section of a permanent way. Explain briefly the functions of
the various components of the railway track.
a. Rails
- Double Headed Rails - Double headed or Dumb-bell rails are rail sections that
have the same size at the foot and head. These rails were first commonly used
on railway tracks. The rationale behind employing these rails was that after the
head of the wheel had worn out due to friction, the rails could be reversed and
reused. However, it was discovered through experience that their foot could not
be utilized as a running surface since it likewise became corrugated as a result of
the impact of running. Loads on wheels This type of rail is no longer used by the
Indian Railways.
- Bull Headed Rails - Bull headed rails are rail sections with larger head
dimensions than their foot dimensions. By adding extra metal to the head of this
sort of rail, it is made somewhat thicker and stronger than the bottom half. Chairs
are also required to keep these rails in place. Bull headed rails are very useful for
establishing points and crossings.
- Flat Footed Rails - Flat footed or vignole's rails are rail sections with their feet
rolled flat. Charles Vignole designed this sort of rail in 1836. It was once
assumed that the flat-footed rails could be connected directly to wooden
sleepers, eliminating the need for seats and keys for the B.H. rails. However, it
was later discovered that strong train loads caused the rail's foot to sink into the
sleepers, causing the spikes to come free. To correct this flaw, steel bearing
plates were installed between the flat-footed rails and the hardwood sleeper. In
India, these rails are most widely utilized.
b. Sleepers - Sleepers are track transverse components that are installed beneath
the rails to support and secure them.
c. Ballasts - Ballast is the granular material, generally broken stone, that is put on
top of the railway structure and around the sleepers.
7. Discuss the necessity and effects of the coning of wheels.
- The rims or flanges of the wheels are never level, but rather in the shape of a
cone with a slope ranging from 1 to 20 degrees. This is known as wheel coning.
The coning of wheels is done primarily to keep the vehicle in a central position
with regard to the track.
8. What are the various types of stresses induced in a rail section? Explain briefly
how these are evaluated.
- The lateral force imparted to the rail head causes the rail to deflect and twist.
Lateral force bends the rail horizontally, and the resulting torque generates a
massive twist in the rail as well as bending of the rail's head and foot. The friction
between the rail and the sleeper, the resistance provided by the rubber pad and
fastenings, and the ballast in contact with the rail all act to oppose lateral
deflection of the rail.
- The longitudinal strains in the rail are caused by the locomotive's tractive effort
and braking force. Temperature changes, particularly in welded rails, produce
thermal forces, which cause the formation of strains.
9. Explain the following terms.
(a) Track modulus - The vertical rigidity of the rail foundation is measured by
track modulus. Track stiffness is another characteristic that measures the vertical
rigidity of the complete track system. Both are associated with track performance.
(b) Coning of wheels - The flanges of railway wheels are constructed with a slant
of 1 in 20. This is known as wheel coning. The tread of a railway vehicle's wheels
is not flat, but slanted like a cone to allow these vehicles to operate smoothly on
curves as well as linear straight track.
(c) Tilting of rails - Rails are tilted at an inclination of 1 in 20 to decrease wear
and tear on both the tread of the wheels and the rails of the railway track.
(d) Permanent way - A railway track or railroad track is the construction on a
railway or railroad that consists of the rails, fasteners, railroad ties, and ballast,
as well as the underlying subgrade. It allows trains to travel by providing a stable
surface for their wheels to roll on.
