Snow and Ice – Why is it such a problem?
We often get asked by many of our passengers why snow and ice have such an extreme effect on our services. There’s no quick answer to this question, so together with our industry partner, Network Rail, we thought we’d give you all the information you need to know here.
Our network and our trains
The Southern network has 414 miles of track, covering East and West Sussex, Surrey, South London and parts of Kent and Hampshire. The track and signalling equipment – known as the rail infrastructure – is owned, operated and maintained by Network Rail.
Most of the trains we run are powered by electricity via a third rail DC electrical system. This third rail is located to the side of railway tracks and is known as the conductor rail. The trains operate by drawing electricity from the conductor rail via ‘shoes’ fitted to the trains.
We also have a fleet of diesel trains which run on the Uckfield Line and on the East Coastway. These trains have their own power and so can run independently of the electricity supply.
So what happens when it snows or it gets icy?
During freezing temperatures or snowy weather, ice can form on the conductor rail effectively creating a barrier between the rail and the shoes on the train. This can be caused by compacting of snow and ice that falls or forms on the rail. It can also occur when it rains during sub-zero temperatures. The conductor rail can be more than 10°C colder than the air temperature, so the rain water freezes instantly when it lands on the rail, forming a layer of ice. As ice does not conduct electricity, this prevents the train from drawing power, causing the train to run at reduced speed and, in extreme circumstances, can lead to trains becoming stranded where no electrical current can be drawn.
Another issue that can affect trains is ice forming on the running rails. Whilst ordinarily this isn’t a problem, sometimes if a train comes to a stop on a gradient or slope, it can be difficult to gain enough traction to get going again. Occasionally this may mean that a train can become stuck.
During heavy snow, such as that experienced in December/January 2010 (the worst this country had experienced for almost 30 years), other factors can affect the railway. Many railway employees need to use roads to either get to their place of work or get to the location where a problem may have occurred. If road conditions are bad, it can hamper our ability to run the railway or respond to incidents. In rural locations, we have also experienced occasions where the weight of the snow has caused trees to fall onto the track, which need to be cleared before trains can make their journeys.
What do Southern and Network Rail do to prevent these problems occurring?
We monitor weather forecasts constantly. When very cold weather is forecast, all non-essential maintenance or rail improvement works are cancelled by Network Rail. This is because when much of the work is carried out trains cannot operate along the route. Therefore if the work takes place during wintry weather there is a greater likelihood of ice building up because there are no trains running along the tracks. Cancelling the work also frees up staff to be deployed to key locations, responding to incidents and keeping trains running.
Heated anti-icing fluid is laid on the conductor rail to try to prevent ice from forming. This fluid is applied by a dedicated fleet of specially adapted trains which run across the network around the clock. Although primarily an anti-icing agent the fluid also has some de-icing properties to help melt any ice which has formed.
Southern runs empty passenger trains - known as ghost trains - overnight across the Southern network, especially in areas which are more vulnerable to freezing conditions. This activity also helps prevent ice building up on the conductor rail. As the shoes on these trains come into contact with the conductor rail, they scrape away any small build up of ice before it becomes thick enough to prevent proper connection between trains and the conductor rail.
During bad weather, all of these countermeasures are employed. However, sometimes, the laying of anti-icing fluid is followed by a band of heavy rain which washes much of the fluid away or dilutes it before it has had the chance to do its job. This set of circumstances is particularly challenging and Network Rail engineers are currently considering how to improve the effectiveness of this particular activity.
Southern’s train fleet comprises a number of different train types, with the majority being ‘Electrostar’ trains. These trains have sophisticated systems that are designed to protect themselves and neighbouring signalling equipment from electrical interference operating outside certain parameters. Icy conditions can be a threat to the electrical systems on the trains and signalling equipment, but for this year’s winter, new software has been developed jointly between Southern, Network Rail and Bombardier (the train’s manufacturers) which has been deployed across the Electrostar fleet. This new software allows the trains to draw more power in icy conditions than they could previously, thereby reducing ice-related delays.
That’s fine, but why do diesel trains become affected?
Diesel trains generally cope very well with snow and ice as they have their own power source. However, they share the same stretches of track as electric trains, or connect to electrified track at some point on their journeys. If diesel trains are affected, it is generally because they become delayed, or come to a standstill as a result of problems with electric trains further up the line, or as a result of problems with the rail infrastructure.
Why do we change timetables from one day to another?
The rail industry puts a lot of time and effort into planning. Although we have contingency plans in place for extreme weather, the timetable we provide for you during severe weather is always dependent on the conditions at the time, and as these conditions tend to change rather quickly, a different or revised timetable may be in operation each day. We can assure you that we always try and provide the best possible train service for passengers.
When we do experience snow and icy conditions, the best way for you to find out what’s happening is to log on to our website to get up-to-the-minute information on the service, and for the next day’s timetable information, log on in the afternoon or evening, where details of the following day’s timetable will be displayed. Alternatively, passengers can contact National Rail Enquiries.
What about the stations and car parks?
Your safety is our top priority so our staff and our contractors put a lot of effort into keeping platforms, footbridges and station entrances as clear of snow and ice as possible.
We endeavour to keep our car parks clear, but sometimes this is not always possible at larger car parks due to their size and amount of snowfall.
Where we can, we deploy additional staff, many from our head office to assist station staff in the clearing of snow and ice and to help you with information about your journey.
Sometimes, no matter what we do, we still have problems
We do, of course acknowledge that at times, no matter what precautions are taken, there will be isolated incidents where severe disruption takes place due to broken down and stranded trains, and infrastructure problems such as frozen points and power supply problems.
Whenever our services are disrupted by poor weather conditions, we hold internal reviews and reviews with Network Rail to analyse what was done by us both, why it was done, and what could be done better.
We can assure you that Southern and Network Rail’s primary concern is to keep you moving safely by providing the best train service possible during such weather conditions.
