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Railways Airports and Harbour Engineering

by Engineering Kings
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Engineering Kings
Engineering Kings
CE6604 Railways, Airport and Harbour Engineering The Definition of Railway Rolling Stock da ta s.b log sp ot. in It is always useful at the outset of consideration of a subject to pause for a moment and to ponder the definitions, attributes range and scope of the matter. Rolling stock used on railways in the earliest days evolved from carriages and wagons which ran on highways to carry both people and bulk materials. As early as the sixteenth century wooden wheeled carts were used in mines and quarries running on longitudinal timber rails. With the progressive evolution of the skills and crafts of the wheelwright, metalworker and the ironmaker, wheels improved through various phases from simple rough turned wooden spools through spoked and rimmed construction to fully cast and turned metal wheels. Similarly, body construction and springing, particularly for passenger carrying vehicles, relied very heavily on the experience gained in the construction of stagecoaches in the seventeenth and eighteenth centuries. At the end of the eighteenth century, horse drawn trams running on metal rails began to appear in a number of European cities. These horse drawn tramways were literally to pave the way for development of railways when steam power began to be developed Ci vil -
- Ci vil da ta s.b log sp ot. in early in the 1800s. One has only to look at illustrations of early passenger coaches to see how closely they resemble the road vehicles of the previous century. As railway experience was gained, the design of rolling stock also evolved. Springing, body structure, wheels and axles all are subject to varying loads and stresses, when comparing slower speeds on rough roads to much faster speeds on railways, with a comparatively smoother ride. Railway rolling stock generally runs on hard wheels on hard rails. The wheels are not only supported by the rails but are guided by them. The only exception to this is for a small number of metros where rubber tyres have been introduced. In this case the supporting function of the rail may be separated from the guiding function. In all cases railway rolling stock will transmit vertical, horizontal and longitudinal forces to the track and its supports. Most railways have adopted twin rails and flanged wheels. Forces are transmitted to the rail structure either by direct bearing on the rail top from the wheel tyre, or by bearing laterally through the flange, or by longitudinal friction. Potential ‗overturning‘ forces, caused by centrifugal force on curves, coupled with wind forces on exposed locations are resisted by vertical dead weight and super-elevation or ‗cant‘ on curves. The Range of Railway Rolling Stock Today there is a very wide range of rolling stock used throughout the world on different railways. This range includes the following basic types: • Locomotives • Freight wagons • Passenger coaches • Multiple units (with motive power in-built) • Metro cars (usually multiple units) • Light rail/Trams (usually articulated units) • Rail mounted machines (cranes, tampers etc.) -
- • Inspection and maintenance trolleys log sp ot. in The Objectives in Station Planning In planning any station the following objectives need to be kept very much in mind: • Attractiveness in appearance. • Free movement of passengers. • Safe evacuation in emergency. • Access for the disabled. • Access for emergency services. • Safe accumulation and dispersal of crowds. • Reliable operation of train service. • Resilience to failure. • Cost-effective investment. Ci vil da ta s.b Planning for Normal Operation The degree to which the business is prepared to invest in providing space purely for the added comfort of passengers must be decided by each railway system based on its own market position and objectives. The starting point for any station planning is the demand forecast. This must be accompanied by a detailed knowledge of the likely train frequency from each platform and the time staff would need to take action when problems arise. Given working assumptions, it is then possible to determine how many people are likely to have accumulated within a particular area before control measures can be instituted. The operator must determine his own relative values for key variables which combine to determine the minimum size and capacity for any element of a station. These will include: • time needed to become aware of a problem. -
- ot. in • staff reaction and decision time. • action implementation time. • accumulation rate for passengers. • maximum density for safety. The frequency and destination pattern of the train service is also a key factor in the sizing of station infrastructure. Assuming, for instance, that the total staff reaction time is effectively five minutes and that the normal peak service is at five minute intervals, capacity at the platform must allow for at least twice the normal numbers expected in the peak. Ci vil da ta s.b log sp Capacity Requirements It is recommended that the following limits should be applied to station areas for demand levels under normal peak conditions: Platforms, ticket halls and concourses — 0.8 sqm per person Passageways • one way — 50 persons per minute/m width • two way— 40 persons per minute/m width Fixed Stairways • one way — 35 persons per minute/m width • two way— 28 persons per minute/m width To allow for ‗peaks within a peak‘ it is wise to use the calculated peak fifteen-minute flow figure, which can be derived from the one-hour figure by multiplying by 0.3. Similarly the peak five-minute flow figure can be derived by multiplying the fifteen-minute figure by 0.4. This five-minute figure should be used when testing the layout ‗tight spots‘ to ensure that dangerous situations do not occur during the short lived period when crowding exceeds desirable levels at a restricted localised point. The capacity of entrances and exits to street level should follow the guidelines above. From subsurface ticket halls/concourse areas there should be at least two exits to the street each of which must be able to take the full peak level demand albeit under crowded conditions. -

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