Hazard Rail power systems
Knowledge and understanding
|Rail power systems||
Understand all associated hazard knowledge
Railways can be operated by numerous power supplies including steam, electrification, diesel and batteries.
Steam engines can be found on heritage or prestige passenger services. Additional hazards from these vehicles include:
- High fire loadings (including fuels such as coal)
- Source of ignition
- Steam and high pressure steam
- Boiler and boiling water
Due to the nature of the pressure systems, it may be hazardous to apply water to steam boilers or engine fireboxes. Specialist advice for this type of rail vehicle should be used to inform the risk assessment and tactical plan.
These can operate under a number of systems and voltages, using the following traction power supply systems:
- Overhead line equipment
- Contact rail equipment (often referred to as third or fourth rail supply)
An electromagnetic field (EMF) is produced whenever a piece of electrical or electronic equipment is used – this applies to electrified railways. EMFs may interfere with fire and rescue service communications including radios, mobile phones and telemetry systems. Refer to Electromagnetic fields (EMFs) for further information.
Overhead line equipment
Overhead line equipment (OLE) refers to the overhead wires and supporting infrastructure that carry electricity at 25,000 volts to power electric trains. Electricity is delivered to feeder stations, then distributed to substations along the railway, which then feed the OLE. The voltage may be lower, between 550v to 1500v, for light rail vehicles, such as trams and metros. The rail vehicle obtains their traction power by picking up electricity from the OLE via a roof-mounted pantograph. For further information about OLE, see the Network Rail website: Overhead line equipment.
Each OLE structure has an identification number, which can be useful when communicating the location of an incident to the electrical control operator (ECO).
OLE, pantographs and all roof-mounted electrical equipment on trains are extremely dangerous. It may be fatal to go too close to them, or if direct or indirect contact is made with them. They should be treated as being live at all times, unless formally confirmed otherwise by the ECO.
Each (OLE) structure has a cable connecting it to the running rail. This is known as a bond. Some bonds are coloured red and are dangerous if they become disconnected. They must not be touched, and should be reported to the rail infrastructure manager or railway incident officer (RIO), to ensure control measures are adequate.
OLE is under tension and therefore, if damaged, it could collapse and recoil with force, remaining electrically charged until safely isolated and earthed.
Rail vehicles display a cant rail warning line; this indicates the safe height limit if there is overhead line equipment (OLE) present. The line should be clearly visible when viewed from rail level or platform height. The warning line is normally painted orange, unless this conflicts with the train operating company’s livery, in which case it may be black or white.
For further information about OLE and the procedures for dealing with equipment, see the RSSB publication, Handbook 16: AC electrified lines.
Conductor rail equipment
Conductor rail equipment (CRE), sometimes referred to as third or fourth rail systems, use conductor rails carrying direct current. The trains have metal contact blocks called collector shoes (or contact shoes or pickup shoes) which make contact with the conductor rail.
For further information about conductor rail equipment (CRE) and the procedures for dealing with it, see the RSSB publication, DC electrified lines.
CRE, shoe gear and under-floor mounted electrical equipment on trains are extremely dangerous. Direct or indirect contact with this equipment may be fatal. This includes allowing any clothing, tools or equipment to touch the CRE components.
Personnel should not step into any flood water that is in contact with the CRE, and should not apply jets of water or other firefighting media to the CRE.
Some conductor rails are fitted with heating systems, to prevent ice and snow forming and compromising traction. Conductor rail heating systems are normally powered by electricity, which should be isolated before approaching them.
In the absence of overhead line equipment (OLE) or conductor rail equipment (CRE), rail vehicles will be self-powered, usually by diesel traction. Diesel powered rail vehicles can only be stopped by giving instructions to the driver or when the vehicle reaches a stop signal. Diesel rail vehicles may carry significant amounts of fuel, lubricants and batteries, and locomotives and some carriages will be fitted with electric alternators and electric traction equipment.
Gradually being developed and introduced to the rail network are rail vehicles powered by a number of alternative fuels, including:
- Batteries, either as the sole traction power source or recharged by overhead wires on electrified tracks or by charging stations on non-electrified routes
- Liquefied natural gas (LNG)
- Hydrogen fuel cells