Course:SPPH381B/TermProject/Alkaline battery- Samin/Track ballast

Introduction

Diagram showing cross section of double track railway alignment including an overhead power supply system.

Track is the base upon which the railway runs. To give a train a good ride, the track alignment must be set to within a millimeter of the design. Track design and construction is part of a complex and multi-disciplinary engineering science involving earthworks, steelwork, timber and suspension systems - the infrastructure of the railway. Many different systems exist throughout the world and there are many variations in their performance and maintenance. The first step is to create a railway formation (the foundation on which the railway lies). This is flattened, ready for ballast to be laid on top.

Ballast is provided to give support, load transfer and drainage to the track and thereby keep water away from the rails and sleepers. Ballast must support the weight of the track and the considerable cyclic loading of passing trains. Individual loads on rails can be as high as 50 tonnes (55 US or short tons) and around 80 short tons on a heavy haul freight line. Ballast is made up of stones of granite or a similar material and should be rough in shape to improve the locking of stones. In this way they will be better at resisting movement. Ballast stones with smooth edges do not work so well. Ballast can be laid to a depth of 9 to 12 inches (up to 300 mm on a high speed track). Ballast weighs about 1,600 to 1,800 kg/cu/m. After that this ballast is leveled and stabilized using special machinery, before laying sleepers at precise intervals all the way along the route. Then the tracks are finally laid on top and fixed into place.

Railways need electrical power for signalling, points and other systems which is brought via the nearest connection points along the railway. This means laying cables in surrounding areas to the line of route, as well as the construction of several electrical cabinets.

List of hazards

Physical hazards

1. Structural/machine failure (of loaders, dozers)

2. Physical injuries (due to loading/unloading)

3. Heat

Chemical hazards

1. Silica dust exposure

Biological hazards

1. Silicosis