“At around 17:50 on Monday 20 March, six loaded wagons of an eastbound freight train became derailed as the train passed over East Somerset Junction, between Castle Cary and Frome, while travelling at about 20mph (32 km/h). The train, the 17:05 service from Merehead to Acton yard, was joining the up Westbury line from the Merehead single branch line.

“There were no injuries. The accident resulted in substantial damage to the railway infrastructure; around 100 metres of track including two sets of switches and crossings were destroyed. Train services between London Paddington and the West Country were diverted via Swindon while the wagons were recovered and track repairs took place over the following four days.”

These are the necessarily stark and clinical words at the start of a recent industry brief by the RAIB (Railway Accident Investigation Branch).

The words say it all. A train came off the line, caused considerable damage and the line was eventually reopened four days later.

Relatively straightforward incident

Here at the Rail Engineer magazine we have covered several mishaps in the past. Mostly we have concentrated on the engineering needed to put things right – and sometimes the engineering that caused the initial problem in the first place!

This time we’re taking a somewhat different approach. This was, after all, a relatively straightforward incident – albeit reasonably spectacular.

We’re going to look at how the incident was managed from a railway operating point of view, rather than the detail of the remedial works.

Why? Well, we feel it’s useful for engineers to understand what is going on in the background, when sometimes it may seem that attention is on other things.

So, follow us now through the events of Monday 20 March and get a feel of how the railway, as a whole, dealt with the aftermath of the derailment of 7Z15.

The alarm

Neil Latham is the acting senior incident officer working for Network Rail, based at Swindon. Network Rail has three levels of incident command – gold, silver and bronze. Neil carries out the duties of a gold command officer, taking on strategic overviews of major incidents.

At almost 6 o’clock on the Monday evening, he was just putting on his coat ready to go off duty when an alarm rang in the control room.

“Think of the alarm that they set off in Star Trek. That’s the sound it makes,” he described it.

This alarm goes off when a driver’s emergency button in a loco cab is hit. There is a direct line between the driver and the nearest signalbox with the conversation relayed over loudspeaker to the Swindon control room.

The alarm got everyone’s attention. They listened to the words of the driver who explained that his train was derailed at East Somerset junction, that several wagons were involved and that all lines were blocked.

Neil took his coat off. Going home would have to wait.

An abrupt and unplanned halt

East Somerset junction lies between Frome and Castle Cary on the main line between Reading and Exeter. It is the junction between a single line leading to a quarry at Merehead that supplies a wide range of aggregates to the building industry.

It’s known locally as Witham, being close to the village of Witham Friary. To non-locals – the media especially – it is known as Castle Cary (which is eight miles away!).

The train in question was bound for Acton yard in west London and was hauling around 3,800 tonnes of aggregate, shale, rock ballast and sand. As it travelled onto the main line it came to an abrupt and unplanned halt. The driver applied more power but nothing happened. The brakes came on.

Looking out of his cab window, all he could see initially behind him was a cloud of dust. As this settled it was obvious that the middle part of the train was on the floor.

The signaller placed all signals in the area at danger, although damage to signalling equipment by the derailment had already caused signals to go to red.

In the control room, the controllers set about dealing with an incident that they could tell from just a few words was certainly not going to be cleared up in 20 minutes.

Training kicks in

Network Rail carries out regular practices of train disruptions, and Neil emphasised that managing an incident is much more about considering the railway in the future rather than looking backwards at the incident itself and the causes of the incident.

The incident has happened. That’s the end of the matter. Why it happened is for others to worry about.

“If you get involved in analysing causes in the first few minutes or hours, then the effective management of the railway as a whole becomes distorted and very difficult,” he commented.

The track circuit diagrams are mimicked in the Swindon control room and so it was possible to see what the signaller could see. The diagrams were quickly photographed and, from those images, the controllers could understand which routes in the area were blocked and which were available. With information gathered from other boxes, it was possible to tell whether there were any trains trapped and whether there were trains that could become trapped. These latter were diverted and diversionary routes planned for any following trains.

It is the role of the controllers to sort out vital details such as driver route knowledge, platforming, stabling, stock availability and all the minutia any one of which could prove to be a showstopper.

In the meantime, the trapped trains had to be drawn back to stations where passengers could be disembarked and transferred to road transport.

Setting all this up has to start straightaway, as does the briefing of all parties involved. These included the RAIB, the freight operator, the passenger train operator, the DfT and the infrastructure maintainer. The Network Rail’s breakdown crane was mobilised.

No rushing off to site

There was intense activity, but none of it involved a mass exodus to site. As Neil emphasised, there was absolutely no point. The site would have been quarantined and, with several hundred tonnes of steelwork sat firmly on the floor, nothing was going to move and nothing could be moved until a detailed recovery plan was set up.

Around 45 minutes after the incident – 45 minutes that passed pretty quickly – a conference call was set up with those involved in the medium and long-term management of the incident.

During this conference, the appropriate command structure was confirmed and the aims and objectives of the operation defined.

Very early on, it was appreciated that the coming weekend involved some very extensive engineering work in the area which, in turn, required a diversionary route over the site of the derailment. This defined the timescales for the recovery and reinstatement work.

A basic railway was needed by 22:00 on the Friday. If this deadline was missed then there was a real risk that the engineering work could be disrupted or cancelled.

Again, the natural instinct of people to go and help had to be curbed. With the short-term measures already being planned, it was far more useful to set up rotas and send everyone home so that they could arrive on site when there was something to do and to ensure fresh cover through the incident.

Through the night, controllers worked on the temporary timetable that would operate over the next 48 hours.

In the morning, the RAIB arrived and began its investigations. A small team from Network Rail was allowed access so that an inventory could be made of the damage. This enabled a first ‘stab’ to be made at sourcing materials and other resources that would be needed. It was not a detailed survey, but enough to make at least an upper-bound evaluation of what had to be replaced.

Wagon recovery plans

The wagon recovery team was also allowed to view the wagons so that an outline recovery plan could be put together. There are two basic options available. Either a wagon can be re- railed with its own or with temporary bogies, or it can be purchased from the owner and cut up either in-situ or having been placed on adjacent land.

Each vehicle had its own bespoke recovery scheme. With the Friday deadline in mind, the method of recovery for each wagon was determined by the time that it would take.

“In the end,” Neil recalled, “all of the wagons were railed out despite some of them looking a bit hopeless.”

As the wagon recovery timescale became clearer, the track and signalling engineers were able to plan their operations working back from the 22:00 Friday deadline.

The last wagon was dispatched on Thursday morning. Track reconstruction took place from Thursday afternoon and all through Friday.

Access was not an issue as there is an existing road close to site. There was no need to put in temporary access over farmland, although the farmer did benefit from acquiring all the spoil!

Some track materials were on hand locally, and one of Network Rail’s main hub depots was not far away, at Westbury, and it had everything else that was needed.

“By the Friday deadline we had got 50 per cent of the railway back with full signalling restored. Of the two lines that come on to the main line, we had replaced one and abandoned the other one until a later date.

“Passenger services were pretty much unaffected, apart from a temporary speed restriction which caused only minimal delay.”

The planned engineering works at the weekend were able to go ahead with the diversionary routes fully available.

In those minutes immediately after 17:50 on the Monday, not only had a strategy to maintain the weekend work been formulated, a functioning railway system had been set up around the incident site.

The railway can never just stop. There are people and freight that need to keep moving and it takes the calm practiced expertise of the controllers and the incident officers to ensure that they do.

Written by Grahame Taylor