1 - Intro and Background

Question 1

Categories the rail industry can be split into

Answer 1

Mainline network
Underground railways
Light rail and tramways
Minor and heritage railways

Question 2

UK legislation

Answer 2

Railways Act
Health and Safety at Work Act
Railways Interoperability Regulations

Question 3

EU legislation (now UK law)

Answer 3

Regulations concerning European rail network for competitive freight, allocation of railway infrastructure capacity, levying of charges for the use of railway infrastructure
Particular focus on ‘inter-operability’

Question 4

Government bodies related to industry

Answer 4

Department for Transport
Transport for London
Office of Rail and Road
Additional bodies in Scotland and Wales

Question 5

Safety bodies in the industry

Answer 5

Rail Accident Investigation Branch (investigates rail accidents)
Rail Safety and Standards Board (conducts research and gives advice on safety and cross-industry issues)

Question 6

Companies in industry

Answer 6

Network Rail (rail infrastructure owner and operator)
Train operating companies (operate passenger trains, to be combined as Great British Railways from 2024?)
Freight operating companies
Rolling stock companies (own and lease trains to train operating companies)

Question 7

Points about UK rail network

Answer 7

Approx. 2500 stations on main rail network
20,000 miles of track
40,000 bridges and tunnels
Track is managed by Network Rail (government owned)
Trains are run by other companies (several in public ownership or as management agreements with government)
‘System Interface Committees’ exist to help track and vehicle companies work together

Question 8

Typical design life of passenger vehicles

Answer 8

30-35 years

Question 9

Typical passenger vehicle suspension

Answer 9

4 axles per vehicle
Mounted in pairs on bogies

Question 10

Typical length and weight of single vehicles (coaches)

Answer 10

20-25m
40 tonnes

Question 11

Why are two suspension systems used?

Answer 11

Each can be tuned to a different frequency

Question 12

Why are bogies used?

Answer 12

To allow a long vehicle to move around a curve
Allow good support of vehicle and ability of wheels to align with track curvature

Question 13

What would happen if the bogies are too far apart?

Answer 13

Wheels badly aligned
Fail to corner well
Likely to derail

Question 14

What would happen if the bogies are too close together?

Answer 14

Makes the vehicle very unstable

Question 15

Wheelset components

Answer 15

2 wheels
Axle

Question 16

Points about wheel design

Answer 16

Flanges are not what keeps wheels on the track
Wheels are ‘coned’ in opposite directions - linking them by an axle creates self-aligning system which should run without flange contact
Rails have a curved surface to create a ‘point’ contact

Question 17

Points about steering

Answer 17

Around a corner, outside wheel needs to roll further than inside wheel
Coning allows this to happen in controlled way
Wheelset shifts laterally, changing wheel radius at contact point
Larger (outside) and smaller (inside) radius enable wheel-rail contact to stay close to pure rolling at both sides and go around the corner
Excess sliding in the contact leads to rail and wheel wear and consumes energy

Question 18

Typical rail gauge

Answer 18

1435mm (4ft 8.5in)

Question 19

Define cant

Answer 19

Difference in height between low and high rails

Question 20

Points about cant

Answer 20

Height difference means a component of train weight is directed towards centre of curve
Allows train to corner faster
Cant needed depends on speed - must be set to accommodate speed of trains using the line
Tilting trains are for passenger comfort
Angle of body doesn’t change equations of circular motion
Limiting factor on cornering speed is passenger comfort

Question 21

Maximum possible cant for stationary trains

Answer 21

150-180mm

Question 22

Points about below the rail (not solid)

Answer 22

Rails fixed to sleepers
Sleepers lie in ballast (crushed stone) for load distribution and drainage
Ballast controls track stiffness - how much it moves under load
That movement controls rail bending, large crack growth and vehicle dynamics

Question 23

Points about below the rail (solid)

Answer 23

‘Slab track’
Rails fixed to stiff, but not rigid, concrete slab
Transfers load to underlying ground and maintains track alignment
Expensive to build, high environmental impact from CO2 generated in concrete manufacture
Difficult to repair
Often used for very high speed lines

Question 24

Main rail shapes

Answer 24

Flat bottom
Bullhead

Question 25

What is a railpad?

Answer 25

Used in fixing between rail and sleeper to reduce noise and control vibration

Question 26

How are wheels produced?

Answer 26

Forging

Question 27

Typical wheel diameter

Answer 27

650-1250mm

Question 28

Points about power supplies

Answer 28

Around 40% of GB network has power supplies for electric trains
25kV AC overhead supply, provided through overhead cables (catenary), collected by a pantograph on roof
750V DC third rail supply, third rail alongside running lines, collected by shoes fitted to the loco or train bogies
71% electric, 18% diesel, 7% bi-mode trains, 4% loco hauled

Question 29

Electrification benefits

Answer 29

Cleaner
Potentially ecologically better than diesel

Question 30

Electrification drawbacks

Answer 30

Moving interface between wires and train is a failure point
Wires wear out, repeated movement leads to fatigue cracks, severe weather (climate change) takes systems beyond design loads