What goes above the subgrade in a railway track ?
The ballast
What sits on the ballast in a railway track ?
The sleepers
In what order do the fixing, pads, and rails go above the sleeper?
The fixings fix the pads in place, which the rails then go on top of.
What is the function of a rail?
To provide an even ride with low frictional energy loss.
To guide the vehicle safely and spread loads to the sleepers
What is the function of pads in a railway system?
To reduce rail/sleeper contact forces.
To reduce vibration and noise and to insulate electrically.
What is the purpose of a fastening system?
To attach the rail firmly to the sleeper.
What is the purpose of a sleeper?
To spread load from the rail to the ballast and maintain gauge.
What are the key roles of the ballast ?
To resist force from the sleepers, to absorb energy/noise, to spread load to the subgrade, to allow drainage, to alleviate frost problems
What is the key factor about the subgrade ?
You have to work with the subgrade you have !
What is the first operation of constructing a railway?
Prepare the subgrade.
After preparing the subgrade, what do you do ?
Place and compact all layers of to the underside of the ballast.
After you have placed and compact all layers of to the underside of the ballast, what do you do ?
Place part of the ballast.
After you have placed part of the ballast, what do you do ?
Seat sleepers on the ballast
After sleepers have been placed, what do you do ?
You place pads on the sleepers
After pads have been placed on the sleepers, what do you do?
Place rails in correct alignment
After rails have been placed in correct alignmnet, what do you do?
You attach fastening devices
After fastening devices have been attached, what do you do?
You weld up/bolt rail sections.
After bolt rail sections have been welded, what do you do?
Place more ballast around the sleepers, you tamp, and then let the trains compact the ballast for you !
How much does ballast cost per km of track?
£90,000 per track km.
How much does steel rail cost per km of track?
£90,000 per track km.
How much do concrete sleepers cost per km of track?
£90,000 per track km.
Due to costs like earthworks, drainage, services, structures etc, how much does a track cost per km?
£10,000,000
How long do rails tend to last?
10-20 years
How long do sleepers last?
Indefinitely, under the right conditions.
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Week 2: Construction Maintenance39
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Week 3: Ballast Properties - Fouling58
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Week 4 - Sub-ballast & Subgrade, and Guest Lecture37
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Week 5 - Drainage, critical velocity beam on elastic foundation16
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Week 6 - Substructure Stress, Dynamics Temperature Changing62
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Week 7 - Other Forces on Track and high speed issues30
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Week 8 - Sleepers, Fasteners, Wheel-Rail Contact, Wear, Fatigue Fracture55
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Week 9 - Switchings and crossing, alternative track types45
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Week 10 - Light Rapid Transit Alignment34
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Week 11 - Signalling & Control36
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Problem Sheet 120
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Problem Sheet 212
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Problem Sheet 322
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Exam Questions42
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2021-2022 Paper12
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2022-2023 Paper6
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2023-2024 Paper4
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2024-2025 Paper6
