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The greatest advantage of a railway over a road is the saving in tractive effort. The resistance of steel tyres on steel rails is of the order of 0.5 percent of the load, compared with about 2.5 percent for rubber tyres on good road surfaces.
Rail transport has its advantage in transporting large consignments of bulk products over long distances. As the vehicles are confined to a limited network of tracks rail transport is often less convenient than road transport. Environmentally rail transport is far less polluting than road, particularly if the rail system is electrified. The accident rate for rail transport is also far less than for road transport.
Rail transport suffers from a lack of convenience, the need to double handle consignments and the inability to provide door to door service.
A fundamental characteristic of normal duo-rail (or two rail) systems is the gauge of the railway. The gauge is the distance between the inside or running faces of the rails. The accepted standard gauge is 1.435 m (4 ft 8 in imperial measure). Broader gauges of 1.52 m and 1.60 m are also used. Narrow gauge (1.067 m) is used in Queensland.
The planning and design of railways follows similar methods to those used for roads, but greater limitations on grades and curvatures exist. The use of curved track is required in all but very flat country, but the total amount of curvature needs to be kept to a minimum. Curvature results in reduced speeds and increased wear on rail and rolling stock.
The greatest constraint on design is the need to strictly control gradient. A ruling grade is the steepest slope over which a fully loaded train can be hauled by one locomotive from a standing start. This is not necessarily the steepest grade which may be used, as some momentum from a moving train may be used to overcome grade resistance.
In bridge design the main difference between a rail bridge and a road bridge is that the live load in the case of rail bridges is a large proportion of the total load whereas in road bridging the dead load predominates. The result is that in rail bridge design greater attention needs to be given to the effects of impact and fatigue.
Individual rail lengths may be joined by using two rolled angle sections called fish-plates. Fish-plates are usually about 760 mm long and have 6 holes through which fishbolts are passed (3 through each rail end). In addition to joining the rails, provision is made within the fishplated joint for thermal expansion and contraction of the rail. A fishplated joint has about 40 to 50% of the strength of the parent rail, and these joints are a major maintenance problem.
The fastening of rails to sleepers may be achieved in a variety of ways. The simplest attachment is formed by driving a 16 mm square dogspike into a 16 mm diameter hole. In the easiest method of rail attachment, four dogspikes are driven into each sleeper (one each side of each rail). As axle loads and speed increases, greater holding power than dogspikes will be required. For heavy traffic, and/or for small radius curves, the rails will be laid on sleeper plates. These plates spread the load from the rail and also allow composite action from all dogspikes in resisting rail movement.
In recent years there has been a trend towards indirect elastic fastenings. These devices provide sufficient force to clamp the rail and sleeper so that rail creep is controlled, and they are sufficiently flexible to prevent the fastening being loosened in the sleeper (which does occur with dogspikes).
For smooth riding the number of joints between rail sections should be minimised. Modern practice is to weld up long lengths of rail prior to laying using flash-butt welding. In the field these lengths may be joined to form continuous rails by the Thermit welding process. Great care must be taken to ensure the correct length of rail is used to form a continuous rail. A neutral rail temperature must be established for the area and the rail laid at this temperature or with allowance for the temperature variation. Rail heaters and coolers are often used for rail laying operations to achieve neutral rail temperature.
A crossover is a connection between two parallel tracks and comprises two sets of points with two crossings. A crossover will be either left or right handed (depending on whether it is has two left hand or two right hand leads). When one track simply crosses over another, a diamond crossing is required. If a turnout from one track to the other is also provided, it is known as a slip.
Turnouts require a set of points and these are known as facing or trailing points depending on their operation with respect to the direction of travel. Facing points may be used to divert traffic into the lead when moving along the line in the direction of travel. Trailing points become facing points when travelling in the opposite direction to the main direction of travel. For single track railways, where travel occurs in both directions, a set of point will be facing for one direction of travel and trailing for the opposite direction of travel.
Orders are received by the train crew via a telephone
or radio from a central train control centre, which has the track divided
up into sections of up to 160 km. Safety of the system is totally dependent
on the train controller as no signalling or interlocking safety devices are
used.
This system requires the train crew to be in possession
of a token (staff) before the train proceeds onto a single line section between
crossing stations. The staff is carried by the last train over the section
to then allow an opposing train to proceed onto the section. Staff and ticket
is used as the safeworking method where the traffic density increases beyond
the 12 trains per day that can reasonably be handled by a train controller.
Again the staff must be in the possession of the
train crew before the train can proceed onto the single lane section. The
staves vary in shape of head and colour and are housed at each crossing station
in instruments which are electrically connected by wiring and operated in
such a manner that only one staff can be withdrawn from either instrument
applying over the section. Electric staff working normally applies to single
lines where there are 20 or more trains per day.
This method allows for operation of points and signals
from a remote location and total track detection and indication. Trains proceed
according to a favourable signal indication, operated from the centralised
traffic control centre. The two main benefits from CTC systems are the reduction
of station staff and the increased operational efficiency of trains.
One aspect of monorails, particularly those where the vehicle is suspended below the rail, is that they are likely to have a high visual intrusion. This has initiated against their adoption in several cases.
Railway operations in Australia are a combination of both Government and privately funded systems. Both carry approximately the same amount of traffic but, since government railways operate mainly multi-purpose, low density lines, the resources within the government sector required to finance the transport task are comparatively much greater.
The major private sector railways of Hamersley Iron and Mt. Newman Mining in north-west Australia are high density, single product lines, operating to the highest international standards.
The main functions of both public and private rail operators in Australia are freight rather than passenger oriented. About seventy-five percent of total earnings come from freight operations, seventeen percent from passenger operations and the remainder from miscellaneous activities.
The physical location of railways in Australia closely mirrors the development of the continent with coastal centres operating as terminii for inland areas. An important feature of the Australian system is the variety of gauges which is a remnant of the development of colonies prior to Federation. There are three principal gauges in use in Australia – narrow (1067 mm), standard (1435 mm) and broad (1600 mm). Although it is now unlikely that Australia will ever convert all its railways to standard gauge, there is a continuing programme of upgrading main interstate routes to standard gauge where traffic volumes are significant.
On many railway systems there are examples proving
that rail can transport materials in bulk in a manner which is efficient
and cost effective.
While the cost of transport is important, the high
intrinsic worth of much non-bulk freight means that a lot of emphasis is
placed on the quality of the transport service, particularly reliability.
Australian rail systems have for a long time suffered from institutional problems
(work practices, industrial relations problems, organisational structures,
etc.) which have made them not very efficient in this area.
Most Australian railways offer reasonable less-than-carload
and parcel services of reasonable quality and at low rates. However this
traffic is often carried at considerably below its cost.
There are still some places where rail motors and
mixed trains provide rural train services as they have for generations. However
these generally run at considerable loss. Over the last few decades there
have been many services of this type which have been closed down, usually
accompanied by heated political debate.
This is a task that rail performs well although
often at a financial loss. The transport of large numbers of peak period commuters
in metropolitan areas is probably best handled by rail and can usually operate
at a profit. However the need to provide off-peak services when patronage
can be relatively small, and institutional problems, make the whole urban
passenger task one where it is difficult to achieve complete cost recovery
by fares.
At present air travel dominates the public transport
component of the non-urban passenger task. However there is significant potential
for rail to play an increased and improved role in this area. The criteria
that probably have to be set for success to occur are:
Page last modified 5 July 2006.