Basically, an irregularity is anything that affects the progress of a train. There are many different types of irregularities that affect the track.
This chapter deals with some of the major types of irregularities.
Your first obligation on finding an obstruction, or any emergency situation, is to protect the site from any other approaching trains. Once the site is protected, you should report the obstruction.
Before you can report any irregularity that you find on or around the tracks, you must be able to report exactly where it is.
You must be able to report the exact location of any irregularity. The location is always identified by the kilometrage, on whichever line you are on, plus the section that you are in. For example, "76.850km on the Main West in the Warrimoo - Valley Heights Section".
C16-1 Derailments and collisions
Derailments and collisions are the greatest safety hazard in any rail system. Derailments can be caused by:
• Train faults such as broken wheels and axles, poorly performing bogies or worn wheels.
• Track defects such as twist, poor line, wide gauge or spread road.
• A combination of train and track defects.
• Misalignments and broken rails, washaways, slips and obstructions.
Collisions can be caused by:
• Misalignments and curve pull-ins when track centres are brought closer together or tracks are moved closer to structures or platforms,
• Derailments where the derailed train ends up foul of trains on other tracks.
Track Inspection and Maintenance practice is aimed at preventing derailments and collisions.
Figure 259 – Country derailments causing significant damage
Figure 260 - Collision between a ballast
train and an Xplorer
Figure 261 - Collision between a Coal Train and a Passenger train
Figure 262 – Derailment on a
Misalignment
Figure 263 Collision with a platform after a derailment
C16-2 Misalignments and pull-ins
Misalignments are usually found in hot weather.
Misalignments are caused by the rails expanding when they are heated. Because they are made in long, continuous lengths there is no room for them to expand as they get hotter. This causes them to "kick sideways" and cause a misalignment.
In cold weather curve pull-ins are caused by the track contracting, causing it to pull out of line. This could cause problems with trains hitting station copings, other structures or other trains.
Both these problems can cause severe ride quality problems, or even damage, to a train.
If they are severe, they can cause a derailment.
C16-3 Breakaways & Broken Rails
Breakaways occur when rails cool and contract. If they contract too much the joints between the rail ends are stretched. This causes the bolts to shear off or the bolt holes to fracture. The end result is that the gaps between the rails becomes much too wide, causing rough riding and the possibility of train derailment, as well as further damage to the rail.
Broken rails occur when there is a structural fault in the rails. The fault eventually fractures when the rail is put under tension due to cooling. Again, this can cause rough riding and possible derailment.
C16-4 Washaways
C16-4.1 Description
During heavy and prolonged rain, the normal drainage channels provided may not be able to deal with the extra water flowing through them, with the result that flooding occurs.
In flat country, embankments may become submerged and saturated. If the water level rises uniformly on both sides of the bank, there will not be a great amount of water flow.
As a result, little damage will occur. If, however, the flooding is confined to one side of the line, bridge and culvert openings will be liable to scour. Should the water run over the top of the track, very serious damage can result. The amount of damage will be dependent on the velocity or rate of flow of the water. Any steps taken to reduce the rate of flow will, therefore, assist in reducing the damage.
The danger point is reached as water first commences to trickle over the formation.
Scouring then starts, first in the ballast and then in the formation. If there is a large difference in the water levels on the two sides of the bank, the rate of flow will be high and damage extensive.
Figure 264 - Flooding Figure 265 - Washaway
Figure 266 – Washaway
C16-4.2 Treatment
During heavy flooding, washaways may be numerous. They may range from small sections of ballast washed away to deep cuts where the whole embankment has been removed. The method of making temporary repairs will depend on the nature and size of the washaway and also the materials and equipment available.
If the ballast only is scoured out, and it is not possible to get ballast to the site, quick repairs may be made by redistributing the remaining ballast. This will lower the track into a long 'slack' and is only a temporary measure to restore traffic. More permanent repairs must be completed as soon as possible.
Ballast bags may be stacked under sleepers to support the track until additional ballast can be supplied. In this method degradable bags (hessian or similar) are partly filled with ballast and placed under the sleeper (under the rail). When additional ballast is laid the bags will eventually rot away leaving uniform ballast.
Where shallow scouring of the formation occurs, temporary repairs can be made by lifting the track and flooding it with ballast, or by laying continuous sleeper pigsties.
For deeper scouring, pigsties, trestles and temporary beams will be required.
Figure 267 – Washaway with sleeper
pigsties being installed
Figure 268 – Washaway with sleeper pigsties being installed
Figure 269 – Washaway with sleeper
pigsties installed
Figure 270 – Washaway with sleeper pigsties installed
Figure 271 – Washaway with sleeper
pigsties installed
Figure 272 – Washaway with sleeper pigsties installed
C16-5 Obstructions
Obstructions can come in many forms, such as vehicles, trees, people, stock, old sleepers, carriage seats, land slides, rocks, etc. All of these things can cause damage and/or delays to a train.