C - Construction

Question 1

From top to bottom list the structure of a track

Answer 1

Rails, Pads, Fastener, Sleeper, Ballast, Subgrade

Question 2

What is the purpose of the rails?

Answer 2

Provide an even ride
Guide the vehicle safely
Spread loads to sleepers

Question 3

What is the purpose of the pads?

Answer 3

Reduce rail, sleeper contact forces
Reduce vibrations
Insulate electrically

Question 4

What is the purpose of the fastening system?

Answer 4

Attach rail firmly to sleeper

Question 5

What is the purpose of the sleepers?

Answer 5

Spread load

Maintain gauge

Question 6

What is the purpose of the ballast?

Answer 6

Resist forces from sleeper
Absorb energy
Spreads load to sub-grade
Allows drainage
etc

Question 7

Outline the construction of a track

Answer 7

Prepare subgrade
Place and compact all layers up to underside of ballast
Place part of ballast
Seat sleepers on ballast
Place pads on sleeper
Place rail in correct alignment
Attach fastening devices
Weld
Place more ballast around sleepers
Tamp
Allow the trains to compact the ballast

Question 8

What is the cost?

Answer 8

Ballast - £30/m^3
Steel rail - £35/m
Concrete sleeper - £50

Question 9

How long do the components last?

Answer 9

Rail - 10-20 years
Sleepers - indefinitely under the right conditions
Fastenings - indefinitely except for a few failures
Ballast - a few months before it goes out of shape, 10-20 years before it gets too dirty