UK’S railways are buckling under the heatwave
Transport bosses search for answers with the train network unable to cope, writes Oliver Gill
Footage last weekend of workers painting train tracks white to reflect the heat brought the plight of Britain’s railways into sharp focus. With temperatures hitting 40C (104F) or more, speed restrictions were hastily brought in across the network alongside pleas for commuters to work from home and warnings of cancellations.
For anyone hoping to venture north from the capital, the situation is even worse. From this afternoon, all locations between London King’s Cross and York and Leeds will be closed.
As extreme temperatures become increasingly common, transport bosses are confronting a network unable to cope with hot weather.
Sam Macdougall, operations director at Network Rail, the state-backed body that owns tracks and stations, said the measures “were a last resort but it is the right thing to do to keep people safe”.
Railways are typically engineered to work within a range of “normal” temperatures. For Britain, it is between minus 10C and 35C. For Spain, they are made to work between 0C and 45C. For Saudi Arabia, it is between 10C and 55C.
The week’s heatwave has sparked talk within Network Rail that Britain may have to adjust its range, perhaps to be between minus 5C and 40C.
The decision to close the East Coast Main Line amid the red weather warning – which will likely force families whose children have already broken up for the summer holidays on to the roads – is primarily a function of it being one of the oldest electrified pieces of track in the UK.
Overhead electric wires running the length of the east coast line between London and Edinburgh are supported at regular intervals by perpendicular gantries also made of steel wires.
In extreme heat, these expand and begin to sag. That drops the height of the overhead electric cable to dangerous levels, meaning it could get entangled on the pantograph – an apparatus on the roof of the train – that connects it to the wires. This contrasts with the west coast line from London to Glasgow, where the wires run through solid gantries made of steel.
Yet that is not the only problem with the east coast. The line also has a number of wooden sleepers in place for support, despite concrete being the norm on most express lines. The wood – which accounts for a quarter of sleepers in the UK – is not as effective at holding steel rails in place, leaving them more susceptible to buckling. The rails can heat up to 20 degrees more than the ambient temperature. Rails attached to
‘The most common adaptation method for railway buckling is reducing the speed limit of a train’
‘Ultimately, faced with weather like we have never faced before, the network will suffer’
concrete sleepers still buckle, but to a lesser extent. In some countries a solid concrete slab is used, which buckles the least. There is a good reason why the UK generally does not opt for concrete slab tracks: they cost approximately four times as much to install as standard ballasted track.
Using white paint – known as “ice paint”, which Spanish railways began trialling last year – is designed to combat effects from sunlight on top of sweltering air temperatures.
The propensity of a track buckling in hot weather is also linked to whether it is straight or curved. Research has found that tracks with bends are less likely to buckle at high temperatures than straight lines.
Research published in scientific journal Climate Risk Management last year concluded: “Although railways with a high curvature are more likely to buckle at lower temperature, the slope of the associated probability curves decline at higher curvatures.
“Tangent [straight] track comprises 93pc of the entire European railway network, thus a large portion of infrastructure is subject to high fluctuations in risk from small changes in ambient temperatures.”
It added: “The most common adaptation method for railway buckling takes the form of reducing the speed limit of a train, which significantly reduces the potential of buckling, as the energy exerted by the train has a squared proportionality to its speed.”
Already in the UK, trains have mostly been limited to 90mph, down from as fast as 125mph. Some will go as slow as 20mph, exerting less force on the tracks. Switching the range that British railways are designed to operate within is unlikely to be cheap, however. Instead, rail sources say changes could be completed over time and during regular maintenance to limit the cost. As Britain struggles to cope, railways in other countries suffer from and are able to deal with far more extreme variations in temperature. In Russia, the world’s third largest train network, temperatures vary from lows of minus 22C to highs of 45C.
The only way to deal with this is to adjust how stressed the rails are to prevent damage. It is neither practical nor cost effective to replicate changes performed abroad, however, due to the variations in short-term weather and long-term climate in the UK. Britain’s tracks are pre-stressed so that they are stress-free when the air temperature is 27C. Network Rail concludes: “The problem is that if we stressed Britain’s rails to the same degree as those in very hot countries, there would be the risk of increased tension on the rails in winter.”
Over the coming days, Network Rail’s extreme weather action teams, or “Ewats”, are to camp out at so-called hot spots, monitoring track temperatures in the hope that they can deal with issues from the heatwave.
Jake Kelly, head of Network Rail’s disruption task force, told the BBC that the company was spending “hundreds of millions of pounds a year on making the railway more resilient but, ultimately, faced with weather like we have never faced before, the infrastructure will suffer”.