Designing out safety risks

~ The safety mechanisms keeping our rail network safe ~

It’s been nearly 200 years since Britain’s first railroad was constructed to connect Stockton to Darlington for the transportation of minerals. Since then, rail transportation has evolved at a rapid pace and now faster, greener and safer trains travel in larger numbers across the nation every day. How exactly does technology enhance rail safety? Here, Simone Bruckner, managing director at power resistor manufacturer Cressall, explains the safety mechanisms protecting the UK’s tracks.

The modern British railway still heavily relies on the initial Victorian engineering at the heart of its development, with a few modernising tweaks along the way. Despite the age of its basic infrastructure, the UK’s rail network is considered one of the safest in Europe, according to the European Union Agency for Railways. Today, the safety of the railways is ensured through a combination of traditional engineering principles, and new technology.

The need for safe speed

Undeniably, the design and engineering behind trains and the tracks is the most essential factor safeguarding the network. The Rail Safety and Standards Board (RSSB) has identified over speeding and lack of effective speed controls as a key risk to passenger and operator safety. Although the instances of over speeding are decreasing year on year, the number of Train Protection and Warning System (TPWS) activations triggered by over speeding was still 171 last fiscal year, according to data from the RSSB.

In addition to the risk of over speeding, as technology advances, trains will continue to get faster and faster. Engineers are constantly developing new designs to enable quicker journeys without compromising on safety or comfort — several trains are now in operation across the globe that travel at over 250 miles per hour (mph).

However, faster trains also bring an increased safety risk that must be mitigated through design. The energy demand involved in decelerating high-speed trains is so large that disk brakes alone are insufficient to guarantee safety. This is why rail typically implements dynamic braking mechanisms in addition to mechanical braking.

Reliable braking control

By using an electric motor as a generator to dissipate excess energy, dynamic braking can facilitate regenerative braking. Within the rail industry, this means that when a train decelerates, excess energy is either transmitted through overhead wires for immediate reuse by other trains on the network or it is stored onboard using a battery for later use.

Regenerative braking is only a viable option when there are other trains in close proximity, such as on underground lines, or the battery is not fully charged. If neither of these circumstances apply, it may not be possible to use all of the regenerated power. Removing this excess energy from the system is essential to prevent damage to other components in the power circuit of the train that could lead to complete system failure. A braking resistor is required to safely dissipate excess energy as heat, keeping the train’s power system operational.

Cressall has supplied resistors to the transport sector for over 60 years and remains at the forefront of resistor technology. The EV2 advanced water-cooled resistor is specifically designed for heavy-duty applications like rail traction. Its unique modular design means up to five modules can be combined to handle up to 125 kilowatts (kW) per unit. Several units can be installed, in parallel or in series, to meet higher power requirements with no upper limit. The unit is proven to meet all major shock and vibration standards required for rail traction applications.

Rail is easily one of the most efficient ways of travelling across Britain, and will only become more reliable with improvements to operations. Combining old with new enables rail design engineers to combine the benefits of tradition with innovation, for faster, greener, and crucially, safer transportation.