05 Rail Joints (Railway Engineering Lectures هندسة السكك الحديدية & Dr. Walied A. Elsaigh)

05 Rail Joints (Railway Engineering Lectures هندسة السكك الحديدية & Dr. Walied A. Elsaigh)

1. Dr. WaliedA. Elsaigh
[email protected]
Asst. Prof. of Civil Engineering
Jumada’-I 1437H
CE 435
Railway Engineering
Rail Joints

2. Textbook
Page 7.1 -7.9

3. Introduction
Rail jointswere used to hold adjoining
rail ends together. In the correct
vertical and horizontal positions.
Rail joints form the weakest
part of a railway.
Rail strength at joints reduces to 50% as
compared to the rest of the rail.
Why needed?To take care of rail elongation “expansions” due
to variation in temperature, through the gap left between rail
ends. Can we NOT use joints?
Can we do without joints?yeh! same as the
system used here in KSA, welded joints. But
then how the thermal expansion is taken
care of? temperature reaches 50
o
Celsius!

4. Types of Rail Joints
Supported Rail Joint
Rail ends rest in a
single sleeper.
Suspended Rail Joint
Rail ends projected
beyond sleepers.
Bridge Joint
Rail ends projected
beyond sleepers. Bridge
plate connect sleepers
single sleeper.
Welded Rail Joint
Ideal joint,
most perfect,
strongest type
weld

5. Cont. Types of Rail Joints
Staggered Rail Joint
Joint of one rail is not opposite to
the other rail.
Length (outer rail) >L (inner)
Staggered Joints
Square Joints
Used at straight
track sections
Staggered joints
are used at
Curved track
sections
Compromise Joint
Two different rail
sections are required
to be joined together
Why do so? Joining
rails of old system to
rails of new system

6. Cont. Types of Rail Joints
Insulated Joint
Insulated joints are used in
tracks having track circuits.
They prevent the electrical
current from flowing
between the ends of two
adjoining rails, thereby
creating a track circuit
section {AREMA}

7. Cont. Types of Rail Joints
Switch Expansion Joint
In the typical design of Switch Expansion Joints (SEJs)
presently used in welded trackon most of the railway
systems
Adapted from http://binametalway.com/switchjoint.html

8. Welded Rails
[Advantages]
Provides perfect joint, increase rail’s life, reduced
construction cost, reduce maintenance cost (20 to 40%).
Reduces creep, expansion due to temperature & friction
of rails.
Joint defects are reduced or eliminated, defects such as
hammering, change of alignment, kinks ...etc.
Longer rails (heavier in weight) can be used (up to 30
m), which dampen the effect of vibration due to moving
loads.
Welding facilitate track circuiting on electrified track.
KSA railway tracks are basically formed of welded rails with diesel
locomotives, can we, at some stage, convert to electric trains?

9. Rails Welding Methods
Electric Arc welding
Oxyacetylene welding
Flash-butt welding
Chemical “thermit” welding

10. Adapted from presentation “ Construction Progress Update”
July 2012 by S.M.A.R.T on Railway track of Hearn Avenue
Cont. Rails Welding Methods

11. Theory of Welded Rails

12. Cont. Theory of Welded Rails

13. Numerical Example

14. Numerical Example

15. Quiz # 3 / 30 minutes
(2) Briefly explain the following rail track maintenance terms:
(a) Packing (c) Dehogging
(3) Draw a neat chart to explain the stages of rail track
construction process.
(4) Explain the main reasons behind reduction of strength
of rail track structure.
(1)Briefly explain the following railway track terms:
(a) Cess (b) Formation Consolidation
(5) Discuss what is termed as “rail roaring defect”,
causes, consequences, and remedy.

16. Homework
The consolidated formation is now ready, and you are the engineer who is
responsible for establishing the railway track between point (A) & (B). Create
a table to show all materials and quantities (Bills of quantity) required to
construct 1.0 km of the single mainline track. Assume welded rails are used.
Makereasonable assumption for any missing information (make clear
statement of your assumptions).
Item Unit Quantity
1. Rails piece 80
2. Sleepers ? ?
Example
Assumption: Rail length is 25 m