Winter Conditions

Freezing temperatures, ice and snow can affect your journeys. Find out more.

Winter weather such as snow and ice can cause disruption to all forms of transport, including road, rail and air services.

This presents a raft of new problems when it comes to running a railway. From door and coupler malfunctions to points failures and snow drifts, the challenges to running a busy and effective train service in winter are varied and significant - but we are doing everything we can to combat it.

No transport service can operate 100% in all weather conditions, but we understand that any disruption is frustrating for you. Here we answer some of the most frequent questions you ask about the impact of the weather on our services – and outline what we are doing to keep trains running and provide you with fast and accurate information regarding your train service.

Our network and trains chevron-down

We operate one of the most complex commuter rail networks in the UK. We run nearly 1,700 trains a day, covering more than 600 miles of track and serving nearly 180 stations covering South West London, Surrey, Hampshire and parts of Wiltshire, Berkshire, Devon and Somerset. The track infrastructure we use – as well as the signalling, points and third rail power supply - are owned, operated and maintained by our partners at Network Rail. Together, we run a dedicated 24 hour, 7 day a week operational control centre where we work to keep trains on our network running as smoothly as possible, as well as dealing with any disruption that occurs and keeping you up to date with the latest information on our services.

Most of our trains – as well as trains operated by other operators south of the River Thames including Southern, Southeastern and Thameslink/Great Northern – are powered by electricity from a track-level third rail DC electrical system. This relatively low-cost system was introduced in the 1920s and 1930s and is different to the system used by trains that draw power from overhead lines. During normal weather conditions, this system works extremely well and we are able to deliver extremely high levels of punctuality to our customers. In addition, we use a small number of diesel trains largely on the London to Salisbury and Exeter route which are powered by fuel and run without any requirement for electrical power.

Why is it difficult to run trains in snowy or icy conditions? chevron-down

Our trains draw power from the top of the third rail, which is located close to the ground. This is unlike more modern third rail systems, such as the Docklands Light Railway, where the third rail is raised and power is drawn from underneath. As a result, snow and ice can form on the third rail during freezing temperatures. This effectively creates a barrier between the rail and the train, interfering with the ability of electric trains to draw power. In these cases, the train can stop and become stuck. The problem is more serious if freezing ground temperatures are combined with snow, sleet or rain.

Heavy snow and icy conditions can also affect the ability of some of our employees to get to their place of work or to locations where there are problems. It can also make underfoot conditions at stations dangerous.

Why don't you replace the third rail with a more modern system? chevron-down

The basic design of the electrification system used in South London, Kent and Sussex as well as our area means that it will never work perfectly during icy conditions. Replacing this system would require massive investment and long term planning due to the large area covered by this system.  These investment decisions would need to be taken by the Department for Transport in conjunction with the South West Trains and Network Rail.

What problems do ice and snow cause? chevron-down
  • Ice build-up can cause issues for our signalling systems by preventing junctions from securely selecting routes, keeping signals at red and stopping the movement of trains
  • Light powdery snow, of the sort that prevented Eurostar trains from running in 2010, can be blown into signalling control cabinets by the line, short-circuiting the important components that keep trains running safely
  • Ice build-up on the conductor rail from which trains draw their power can act as an insulating barrier, preventing trains from accelerating properly or even causing them to lose power altogether
  • Snow making its way into vital components such as the motors on our trains can result in them malfunction and being removed from passenger service
  • Snow settling in equipment required for trains to join (the “couplers” on the front of the train) can stop them from connecting and disconnecting properly at the depot or in service. Ice building up or mixing with snow can also cause damage or malfunction to the train doors, resulting in delays to services
  • Ice forming on the running rails can cause safety issues where trains are unable to accelerate or brake due to the rails being too slippery
  • Freezing rain (formed when snow melts into rain when it is falling, resulting in a super-cooled water droplet that freezes on contact with a cold object), which often appears sporadically and is often not forecast, can effectively encase the conductor rail in a smooth coating of ice, causing issues with the supply of power to our trains.
What are South West Trains doing about it? chevron-down

South West Trains and our partners at Network Rail employ a range of methods to prevent ice and snow settling, and where it does settle to clear it as quickly as possible. These include:

  • Heated points to prevent water freezing, as well as NASA-grade insulation to prevent motors and other parts freezing. Some points and motors have also had additional protective covers fitted to prevent ice forming and damage from ice falling from trains. Staff patrolling the track 24/7 to clear snow and ice where it does form, and this is supplemented by remote temperature monitors, In some cases Network Rail's own helicopter with thermal imaging camera to ensure heated points are working effectively;
  • Horns and other entry points on trains are covered by fine mesh to prevent snow entering. Some of our trains carry bags for their couplers to prevent snow and ice building up, whilst others have heated coupler equipment to ensure they can couple and uncouple as normal;
  • Rail Head Treatment Trains, normally used during the autumn to clear the lines of leaves, are refitted to spray antifreeze and de-icer onto the track to help prevent ice build up on the rails. Extensive laboratory tests have resulted in a mixture known as Arrow - a mixture which causes ice to melt and dissipate, whilst leaving a stickier anti-ice chemical on the rail to help prevent more ice forming later; when conditions worsen, Snow and Ice Treatment Trains are deployed. There are 7 of these trains available for use across the network, and they are fitted with snowploughs and special "icebreaker" shoes to clear the conductor rail of ice. They also deploy antifreeze on their patrols, and will work throughout the night and around passenger services;
  • We will also run empty trains throughout the night and early morning before and after passenger services are running, known as “ghost trains” - these move any ice or snow as it begins to settle, helping clear rails for passenger service in the morning;
  • South West Trains and Network Rail closely monitor weather forecasts for up to a week in advance to plan timetables and treatment schedules effectively;
  • To help prevent door failures on trains, depot staff maintain an ice- and snow-free depot environment, and train crew will clear ice manually from door steps;
  • When conditions become particularly difficult, large numbers of our staff have volunteered to help at their local "home station" - clearing ice and snow and helping grit and salt car parks and platforms with our usual station teams;

In these situations, we may also run a contingency timetable, where trains run more slowly and less frequently to ensure an increased, safer distance between trains to maximise safety. This also helps us to keep our train crews in local areas to minimise any potential chance of disruption.

Should I be concerned about the safety of travelling by train in these conditions? chevron-down

We take your safety and the safety of our staff very seriously and we would never operate a train service unless it was safe to do so. Our focus is to ensure our trains and our stations can be used by our customers safely and with confidence and to do everything we can to minimise the impact of severe weather on our customers.

Why do you decide to run special timetables in severe weather? chevron-down

We would rather avoid severe disruption, but when it happens we know that what you want most is certainty about when and how you are going to reach your destination. Even after all of the precautions taken by South West Trains and Network Rail, very heavy snow will inevitably make it extremely difficult to operate our normal timetable reliably.

We have a contingency timetable prepared and ready for use should snow or ice disrupt our normal timetable. Our snow timetable has a number of features designed to help us deliver a reliable service in challenging conditions:

  • The trains are timetabled to run more slowly (but typically at maximum possible length), giving more time to cope with poor conditions, but continuing to provide as much capacity as we can for you
  • Trains and traincrew are allocated to particular routes (rather than moving between routes and trains during the day as some do during normal operation). This helps to minimise instances of disruption on individual routes causing knock-on problems affecting other services.
What are you doing about stations and car parks? chevron-down

Your safety is our top priority and a huge effort goes into keeping the busiest areas of our network, such as platforms, stations and footbridges, as clear of snow and ice as possible. We have a large stockpile of ice treatment chemicals at stations and at suppliers.  We have also updated all of our station snow and ice-clearance arrangements, buying new equipment where our internal review suggested gaps. Finally, we also have station adoption snow and ice clearance scheme where stations are adopted by back-office staff that live locally.

So what should I do? chevron-down

The temperature on trains may be much warmer than outside, especially during busier peak times. Please follow these tips to be more comfortable on trains during the cold weather.

  • Wear a layer that is easily removed when you board the train, reducing the risk of you overheating.
  • Don't board a train if you feel unwell; please speak to a member of staff who will provide assistance.
  • Eating a healthy breakfast and drinking plenty of liquids will prepare your body for the varying temperatures it is likely to experience.
  • If you feel unwell on a train, it is quicker to wait until the next stop and notify the guard, or get off and seek help from station staff. Avoid pulling the passenger alarm between stations as help is more easily obtained at a station.

During periods of severe weather, we suggest that you:

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