Back in the January Rail Engineer magazine (issue 147), we were introduced to the “Great Divide” – an impressive proposal to enable safer working in tunnels with the added bonus of carrying out that safe work while trains ran at realistic speeds on the adjacent line. That article was supported by some clever 3D visualisations and pictures of the control systems on the plant.

The application was put clearly into focus by a picture of typical tunnel repairs with both lines blocked; meaning closure of the tunnel route or extremely restricted rail service levels.

Rail Engineer has since attended a demonstration of the equipment on the Ecclesbourne Valley Railway, using a short tunnel on the branch line at the Duffield end which offered the ability to put the screen to use with two tracks in place, one running trains and one taking the AMCO screen.

The Ecclesbourne Valley railway is a most attractive heritage line running from Duffield to Wirksworth in the Peak District. Here, the ‘My Test Track’ organisation offers testing facilities on-line with full support.

To put the reasoning for the tunnel screen and accompanying hardware into context, it is worth remembering the history and events that have driven the development.

During the tendering process for Control Period 5 it was clear that Network Rail wanted their suppliers to improve safety performance, reduce cost, innovate and challenge the ways that work has previously been delivered.

Last November, three years into that five-year control period, the Rail Delivery Group stated: “The Railway must harness new technology and change the way we work.” Access to the congested railway network is becoming more and more difficult as the train operators seek to run more and more trains for longer periods of time.

Traditional possession working has been quite appropriate for small interventions and maintenance but, by its own nature, is highly inefficient because:

» A published eight hour possession can give as little as four hours effective working time;

» Working in a blockade only one day out of seven increases preliminary costs;

» Weekend working, with other contractors pressing for the same access times and use of the same access points, is inefficient;

» Wage rates for weekend works tend to be higher;

» Higher plant rates are incurred.

Dave Thomas, AMCO’s contracts manager, emphasised that, to such a specialist contractor, there is a particular resourcing issue. That is, how to keep the highly skilled workforce busy between weekend working sessions – there not necessarily being alternative work during the week.

As related by Dave, the AMCO vision for the future is:

» We want to increase working time on site;

» We want to work in a tunnel at night during the week, and then possibly leave access free for others during the weekend;

» We want to reduce cost and increase efficiencies;

» We want to provide regular midweek work for our specialist tunnel resources;

» WE WANT TO DO IT SAFELY.

There seems to be nothing in the operating rules that prevents blocking one line in a tunnel and carrying out work from that line whilst trains pass on the other line. The conventional safe system of work could be using site wardens – a situation that would be unattractive on any scale.

However; the tunnel screen offers the kind of protection that one has come to expect in the current age and is an innovative idea from the AMCO/ Foulstone Forge partnership.

The demonstration at Duffield was arranged to take the covers off the tunnel screen and share the principles and benefits of the equipment with industry professionals. To emphasise the purpose of the day, Dave insisted that the company wished to hear from experts and work in collaboration with Network Rail. In summary, he told the assembled audience: “We want to make this work!”

The demonstration

A useful asset within the ‘My Test Track’ portfolio is the short tunnel, some fifty metres long, at the Duffield end of the line. The tunnel is of double track arrangement with a through line and a siding with access from the main line at the south end of the structure.

There was considerable interest from industry in the demonstration and, to enable access, the group gathered at the railway’s headquarters at Wirksworth. A very effective safety briefing took place while the assembled occupants rode on a well-presented heritage diesel multiple unit up to the test site at Duffield.

A short train of the AMCO/Foulstone equipment had been assembled in the siding with a Total Rail Solutions (TRS) road-rail vehicle to act as motive power. The focus of the train was the trailer with the screen equipment plus the suction units and a ‘Man- Rider’ which gives a low risk method of getting to the worksite in a safe environment.

The audience was conducted to a safe place behind barriers in the tunnel and the screen and associated vehicles were then shunted into place in the siding.

The equipment performed as planned, with the screen and platform quickly deployed. Most effective then was the inflation of the seals to create a dust tight joint between the screen and the tunnel walls. (In the demonstration only one end screen was deployed to allow easy access for the observers.)

The practicality of the screen was soon demonstrated as the observers were able to take their places on the platform and appreciate the excellent access to the tunnel walls and roof. However the most effective demonstration was to come.

The screen contains filter panels which not only filter air but also mitigate the pressure pulse effect of a passing train. AMCO was able to demonstrate the safety and comfort of the equipment as the DMU was now put to good use, running on the line adjacent to the platform at around fifty kph. It has to be said that, behind the tunnel screen, there was no feeling of risk or any disturbance from the rolling train during several passes.

The base of the tunnel screen gave a very firm footing with risk at the tunnel wall side mitigated by a barrier which was raised to block off the gap between platform and wall.

With the AMCO team on site, there was plenty of advice to deal with questions on both technical and operational aspects. The team were well briefed and was able to advise on piston effect pressures – quoted in Pascals of course! Observers were educated to the sense of differing pressures between approaching and departing trains on the move.

The platform was suited, indeed designed for, concrete spraying – a very effective seal being made with the ability to capture overspray and dusty particles and clear these away into the suction wagon where the dust can be collected for safe disposal later. The concept is not limited to one trailer but, within the limits of the available traction, several units may be coupled togther with easy access from one to another.

After the robust demonstration and safe return of the equipment to the stabling point, the assembled multitude was able to return to the DMU and engage in useful debate during the return to Wirksworth. At the railway’s base an excellent light lunch was provided by AMCO allowing productive networking and further technical briefings.

To complete the demonstrations, AMCO also had a display of other tunnel access equipment, including purpose-built drilling rigs, in the yard at Wirksworth, completing a most absorbing and valuable visit.

Network Rail’s view

As well as contractors and consultants, AMCO was pleased to host Network Rail representatives and Colin Sims, head of tunnels, was able to view the site and the operations. He was impressed with what he saw and commented: “Going forward, the industry will be facing challenges to carry out repairs on infrastructure, even more safely and efficiently, as access opportunities become condensed to meet the ever-increasing demand on network utilisation.

“It is very encouraging to see contractors such as AMCO rising to this challenge and applying their expertise to develop innovative solutions to these problems, as have been exhibited today.”

In summary, the experience of the equipment was very positive, access was safe and the working platform gave every confidence when standing on it. The opportunity to erect access equipment was there and would be quite safe to use.

As well as for use in tunnels, the equipment would also give very effective access to cutting walls such as those through Belper or the approach to Birmingham New Street, giving vegetation control teams the chance to attack the dreaded buddleia without the existing disruption to traffic!

Written by Peter Stanton