Why does snow delay trains

DC-to-Boston Acela Express. The 4 pm is sold out. Along the East Coast, flustered Amtrak agents faced long lines of exasperated passengers who were forced to wait hours for the next available seat. Such scenes have been common in the Northeast this year, which has been walloped by one storm after another since mid-January. Major cities remain buried beneath several feet of snow. Temperatures have been below freezing. It was just over two years ago the Beast from the East brought parts of the country to a snowy standstill, and there have been conflicting reports suggesting it is returning.

Despite this, many rail commuters and travellers often ask the question: Why does snow stop trains running? It would be easy to think that trains should be able to cope with intense weather conditions and snowfall — but this is usually not the case. There are actually plenty of factors that may contribute to train cancellations. Some are quite obvious, others might surprise you.

Most British trains tend not to have snowploughs. Instead, Network Rail use a mix of methods, ranging from independent snow ploughs situated between two locomotives to allow ploughing in either direction through deep drifts, to fitting miniature snowploughs to some locomotives clearing the rail surface.

Trains are also at a much higher risk in slow areas, for instance, when approaching stations or at points. Once the snow has compacted enough to form ice on the tracks, power points can easily be prevented from working. Debris is also a major concern when it comes to snowy weather. Tree branches can snap off in the freezing temperatures, creating obstacles on the tracks. Large ice sheets can also damage trains and tracks, which, of course, can also cause rail points to stick together if they are not already packed with snow.

Beyond environmental issues, the trains themselves can be affected by the chilly conditions, with train door runners jamming because of the transfer of grit salt from the platform to the carriage.

In fact, this was the cause of a derailment in January when a freight train from Inverness was unable to stop on the descent to Carrbridge on the Highland Main Line. It derailed, with the locomotive ending up in a thicket of trees.

Luckily, the driver only suffered minor injuries. In very cold weather, snow and ice can build up on the tracks blocking points, the equipment that allows trains to move between tracks. Ice can coat the electrified third rail and overhead power cables, preventing trains from drawing the power they need to run and leaving them stranded.

Icicles on tunnels, bridges and other structures can also damage trains and overhead power cables. Independent plough. Winter weather fact sheet.