Bridging Dawlish

22nd January 2013

Dawlish, a seaside town on the south coast of Devon about 12 miles fromExeter, was originally a fishing port which grew into a well-known resort in the eighteenth century. In 1830, Isambard Kingdom Brunel designed a pneumatic railway which ran along the seafront of the town. The wide-gauge ‘atmospheric railway’ opened on 30 May 1846 and ran between Exeter St. Davids and Newton Abbot. The first passenger train ran in September 1847 but after technical problems, the Directors abandoned the project in favour of conventional trains and the last atmospheric train ran in September 1848.

Today, while the line is a particularly memorable and scenic route, it is one of the most exposed in the country and the continual battle with sea erosion and corrosion makes it expensive to maintain. Furthermore, the railway station at Dawlish is in the town centre immediately adjacent to the beach and, although most of the station is not the original Brunel buildings, it is all Grade II listed – including the footbridge which links the station platforms. However, the station is so close to the sea that in storm conditions this bridge is drenched by the spray from breaking waves and blasted by wind-born debris (sand) from the beach.

Structural form

The station was originally only a single platform (on the inland side), but a second platform was added in 1858. The existing station buildings were opened in 1875 after the previous wooden buildings burned down in 1873. However, the footbridge was reconstructed in 1937 using serviceable girders that were taken from Park Royal & Twyford Abbey tube Station (a disused station on what is now the Piccadilly Line) after that station had closed in 1931. The bridge had a single square span of 17.5 metres, being supported on padstones built into the masonry of the station buildings (the staircases to access the deck being partly stone masonry within the buildings,

partly timber suspended from the deck). The walkway was approximately 1.8 metres wide. The bridge had a roof with wide overhanging eaves, though the nature of the exposure (sea spray coming in horizontally) is that these had not significantly protected the structure. Additionally, one half of the span had timber cladding to somewhat protect bridge users from spray and sand.

The girders were riveted built-up sections of early steel. The webs had a clearly visible X-brace detail, the visibility of which was exaggerated by the corrosion patterning. This detail, together with the riveted construction, was identified as being a key part of the ‘character’ of the structure and early discussion with the planning and listed building authorities identified that, if replacement was to be adopted, then these features would need to be carried forward into the replacement structure.

Maintain, repair or replace?

The steel bridge was in very poor condition with extensive, well-established and very visible corrosion. Detailed inspection in 2004 had categorised the condition as ‘fair’, though this conclusion was somewhat questionable since, even then, many holes and significant corrosion points were identified. The next detailed inspection in 2010 identified that the defects reported in 2004 had deteriorated significantly and made a less positive assessment of the condition.

A like-for-like repair option was developed, but it required replacement of a large proportion of the structure – eight out of 20 web panels, nine out of 22 web stiffeners and the full length of both flanges on both girders were to be replaced. All the repairs would be carried out with HSFG bolts replacing the existing rivets. Thus, although the structure would look superficially unchanged, most of it would be new.

A further study was carried out by Tony Gee and Partners in 2011. In addition to the known defects, severe corrosion to the girder / cross girder connections was also identified. The condition of the structure had deteriorated to such an extent that some holes in the web had been patched temporarily with hardboard just to remove the risk of public injury on a sharp corroded edge. Detailed analysis identified that not only could the structure not carry the specified imposed load due to corrosion of the members, but even in an ‘as new’ condition the bridge had been under- strength due to a lack of strength and stiffness in the U-frames providing lateral stability to the top flange of the plate girders.

Thus, although like-for-like repairs were estimated to cost approximately £600,000, Network Rail’s preferred option was a replacement structure. A new steel footbridge was considered, but while this could be detailed to reduce the susceptibility to corrosion, the location was such that it could only restart the continued (and probably unwinnable) fight. The station was listed and a simple ‘off-the-shelf’solution would probably not be acceptable.

Accordingly, a wholly fibre-reinforced polymer (FRP) structure was considered, both to simplify installation (by reduced weight) but also, more critically, to reduce ongoing maintenance costs and requirements in the extremely hostile environment. Although this was identified as being initially more expensive than steel, the whole life costs for the structure should be much reduced.

Imposed loading

The bridge was required to withstand ‘normal’ Eurocode footbridge loading and criteria were agreed between the designers and Network Rail. In recognition that the bridge deck may fill with pedestrians (when a train disgorges a large number of passengers at once) the full ‘load model 4’ loading of 5 kN/m2 distributed live load was applied.

Parapet loading in Eurocodes was not well resolved at the time of the design, so this was taken from older standards such as Highways Agency document TD19/06 ‘Requirements for Road Restraint Systems’.

Wind loading is also a conceptually simple code- compliant situation, although the location is exposed and the wind loads are accordingly relatively high.

Aerodynamic stability had to be considered, though this is a variation from the standard as that document does not strictly apply to bridges which have a roof, and the material is not in the list the standard covers.

Lightweight bridges are potentially prone to dynamic response from the aerodynamic loads from passing trains. It was agreed that this effect would be analysed during detail design based on criteria developed during the design of the Bradkirk footbridge (issue 57, July 2009).

Analysis

Initial concept studies considered various truss arrangements. However, due to concerns regarding listed building consent, it was decided to revert to a plain girder design which closely followed the geometry and aesthetic of the original bridge.

To assist with design development and also to obtain planning approval and listed building consent, several computer models and rendered visualisations were generated. A full-scale sample section of girder was also produced to assist the

planners and conservation officer to visualise the FRP structure. The conservation officer insisted that the bridge replicated the aesthetic of the original riveted structure, so imitation rivet heads were bonded to the structure. In some locations, structural bolts are included to provide a backup to the bonded joints and prevent peel stresses in the bonds. These bolts were stainless steel with dome heads to blend in the rivet heads and fastened with tamper-proof shear nuts.

The complete structure excluding the stair units was predicted to have a mass of only five tonnes, which is probably around one third of the mass of an equivalent steel structure.

The structure of the bridge was analysed using computer models and finite element analysis (FEA). Analyses carried out included static, buckling, eigen-value and dynamic response. The roof panels were found to be beneficial in increasing torsional stiffness and vibration frequency.

Simple aerodynamic stability checks indicated that the critical wind speeds for vertical or torsional vortex shedding induced vibration were above 1.25 x design mean wind speed and therefore did not require more detailed investigation.

Design and manufacture

Both the primary structure and the parapet were made up from 1.66 metre deep side girders, each formed from foam cored shear webs, moulded by film infusion using fire retardant epoxy resin and biaxial glass fibre reinforcement, capped top and bottom with pultruded angles and plates to form the girder flanges. Web stiffeners made from pultruded plate provide additional lateral support to the girders, connected to transverse angles below the deck. The girder includes a camber of 120mm along the length of the bridge, which improves the aesthetics and provides drainage to the deck.

The deck was formed from ‘Composolite’ pultruded panels, spanning transversely between the girders. These panels are very lightweight with a skin thickness of only 3mm. To ensure adequate robustness and resistance to local concentrated loads, an additional 3mm thick pultruded plate with a gritted non- slip finish was bonded to the top surface of the deck.

The deck was bonded to the girders and also forms a shear panel to resist horizontal wind loading, removing the need for diagonal bracing below the deck. Unfortunately, the deck has to terminate 2.7 metres from the ends of the bridge to leave room for the stairs. This creates a long length of girder acting as a cantilever and unable to resist the large wind side load. To strengthen these cantilevered areas, additional lateral support plates were fitted to the flanges external to the girder.

The roof transverse frames were fabricated from back-to- back pultruded angles to form T- sections with bonded and bolted joints. The roof frames support longitudinal purlins made from pultruded box section to support the roof panels. These frames also provide lateral restraint to the top of the girder.

To further increase the lateral and torsional stiffness, a much stiffer transverse frame is provided at each end of the bridge. Roof panels are made from standard corrugated fibre-cement panels, and the stair units at either end of the bridge are made from a single FRP moulding, including the stair treads, risers and side panels, hanging from the bottom flange of the bridge girder.

The entire bridge structure was manufactured from FRP materials. The majority of parts are pultruded with glass fibre reinforcements and fire retardant polyester resins to achieve the required structural properties. The pultruded parts used to fabricate the main girder flanges were pultruded in 17.5 metre lengths for the span of the bridge to avoid the need for joints.

Parapet panels have PET foam cores and were moulded from fire retardant epoxy resin reinforced with biaxial glass fabrics using film infusion. Each parapet is in three sections with simple, bonded, butt-strap joints. The final structure was painted to achieve the aesthetic requirements and to provide environmental protection to the composite structure.

Approvals

Since the materials are still considered ‘novel’ by Network Rail, a rigorous design and checking process was implemented. Tony Gee and Partners was appointed to prepare the Form A (Approval in Principle document), complete the design and the Form B (Design / Checking certificate).

Design work undertaken by subconsultant Optima Projects was validated by Tony Gee. In addition, the structure received a full ‘Category 3’ independent check by Parsons Brinckerhoff.

Network Rail managed the process of obtaining listed building consent. This required the production of reports and options studies justifying replacement rather than repair, and was driven through by Network Rail’s own planning and listed building specialists with support from the designers and the initial repair study. Consent was eventually obtained, although the requirements of the process resulted in various detail changes to the configuration from what would be structurally necessary.

The final design mimics the form of the existing structure in order to minimise the visible changes to the various views that take in the station. The new bridge remains part of the listing, and therefore has become probably the first listed FRP bridge in the UK.

Many thanks to David Kendall, Optima Projects Ltd; Ian Smith, Tony Gee & Partners; and Wendy Gough, Network Rail for help with this article.

A new lease of life

21st January 2013

The sheer cost of buying a new fleet of trains is enormous, and in these times of financial hardship there is a strong case for looking for other solutions. Recently, Eversholt Rail announced plans for two projects which will refurbish existing trains to a high standard and allow them to continue operating for the next 15 years. One scheme covers East Coast’s mainline trains and the other the class 321 units currently operated by Greater Anglia.

The current East Coast mainline service mainly uses Inter-City 225 sets, built in the late 1980s, which consist of a class 91 locomotive, a rake of nine Mark IV coaches, and a driving van trailer (DVT) at the other end. They were last refurbished between 2001 and 2006 by HSBC Rail, the then owners, so the interiors are around ten years old.

HSBC Rail was firstly renamed Eversholt Rail and then sold off by the bank to the Eversholt Investment Group, a consortium funded by 3i Infrastructure, Morgan Stanley Infrastructure Partners and STAR Capital Partners, in December 2010. It is looking long-term at refurbishing the sets so that East Coast, or whoever replaces them with the franchise, can continue to use the same trains for the foreseeable future.

Although the Intercity Express Programme (IEP) trains from Hitachi will be coming along commencing 2017, these are not expected to replace the 225 stock in the short term. The operator will therefore be needing a more efficient and passenger-friendly train in the short to medium term.

With that in mind, a mock-up of a Mark IV coach has been built to show off the new thinking, and Eversholt Rail invited the rail engineer to sit in it.

Innovative interior

Noted interior designer Atlantic Design Projects was asked for a concept which would be attractive to passengers, easy to maintain, and have a common theme across three or four classes of travel. These designs were incorporated into a full-scale mock-up, built by Solve 3D of Bedford, for stakeholders to view.

Stephen Timothy, head of relationship development at Eversholt Rail, explained that the brief had been to come up with a style which will give passengers new levels of comfort and convenience while being easy to adapt between classes so that, as traffic patterns change over the course of a franchise, or even over a year, the mix of classes can be readily changed.

Atlantic Design’s directors, Charles Greenway and Graham Love, were pleased to show the results of their ideas. The mock- up looked exactly like the inside of a Mark IV coach. Those items which didn’t need replacing had been retained as there was no need to incur additional cost. So the luggage racks, the walls and side ceilings were merely repainted. The colour chosen was a pale lavender, but all the colours in the mock-up were deliberately chosen to be neutral and therefore to fit in with any franchise’s corporate colours which can be accented with headrest covers and lighting.

The lighting itself, supplied by McGeoch Technology, is LED, ceiling mounted and dimmable. It gives a good general light throughout, so there is no need for over-seat reading lights.

Standard class

Starting in standard class, both table and airline-style seating were shown. The most noticeable feature was that the seating is settee-style and is leather covered. Atlantic Design commented that there is no need to reduce seat quality just because more people are accommodated in each carriage. The settee arrangement, with a centre armrest which completely folds away, means that one person can spread out, or a couple can ‘cuddle up’, or a family can sit with a small child, much more easily than in the more usual individual seats.

To aid both comfort and cleaning, the seat is curved and the join between seat and back cushions is actually partway up the back. This means that the awkward-to-clean split in the back of traditional seats, which fills up with fluff and crisp crumbs, doesn’t exist.

Each seat is made by Rica in Finland from a 15mm thick honeycomb aluminium plate covered with hand-cut silicone foam. This reduces costs, as no expensive moulding tools are required, while also reducing seat thickness. Thus the regular seat pitch can give more legroom, up to 35mm on a table seat or 22mm airline style, or if the current legroom is maintained the thinner seats can actually increase capacity.

Seats are mounted on standard runners which stretch the length of the carriage. One runner passes exactly midway across the width of each seat, so the seat supports and the legs of the tables are between passengers, not encroaching on their legroom. The tables themselves are also curved to maintain the same style, and are covered in wood veneer to give an up- market appearance.

Mounted above the window in line with each seat is the display for the reservation system. Clearly legible, the full colour TFT displays are manufactured in Belgium by Televic Rail and incorporate a simple red/green light – red the seat is reserved or green it is available. That should make finding a seat easier!

Business and First

Business class is a new concept. Individual fully-contoured seats come from Grammer Seating in Germany and are pitched as first class, with one set of seats and a table across a window bay, but four across as in standard class. The tables are similar to the ones in standard class but the window is fitted with a blind.

First class reverts to the settee-style of seat, although with thicker and softer Rogers Corporation silicone foam, and of course the seats are only three abreast. With the thinner seat backs, and a full-bay pitch, tables can be wider leaving plenty of room for two laptops facing each other. Pleated ‘curtains’ can be drawn to cover the windows.

Above First there is Premier class. Individual reclining seats with footrests and padded covers will allow businessmen travelling long distances to sleep on the way and arrive refreshed at the end of their journey. There will only be a few of these seats on each train, at a premium price, but there will no doubt be a demand.

The combination of all these features makes for a good looking and comfortable train. Axminster carpet and Andrew Muirhead leather seating throughout gives everything a luxurious feel. As Stephen Timothy said, “Even standard class passengers have spent quite a lot of money on their tickets, so we should make them feel as though they are getting value for money.” And capacity is up as well, to 579 passengers per train – 44 more than at present.

Locomotive upgrade

Eversholt Rail is planning to invest £20 million in the Class 91 locomotive to ensure its continued operation and increased reliability performance on the new franchise. Not only would this deliver a step change in reliability, but the locomotive would also have extra functionality such as a duplex pantograph (which is currently being trialled on one locomotive on the East Coast), would be ERTMS fitted by 2018 and would have modern compressors and a wheel slide protection system.

In addition, Eversholt has chosen Bombardier as its partner for the development of a full service maintenance product for the IC225 fleet. This enables Eversholt, in conjunction with Bombardier, to offer the successful TOC/franchisee a maintenance package that suits its needs.

An alternative traction option will also be offered in the form of the Bombardier TRAXX UK. This will give the choice of the extra economies and efficiency to be gained from a new locomotive, but at a higher price.

Part of the successful TRAXX family of locomotives, the TRAXX P200 AC UK, to give the locomotive its full name, is an 81 tonne 25kV electric locomotive designed to run within the British loading gauge. Four traction motors supply the drive with a maximum locomotive power of 5.6MW and full regenerative braking is fitted so that, except in emergencies, the mechanical brakes on the coaches will rarely be used. This not only saves all the wear and tear on their brakes, but also reduces energy consumption by returning 10-15% of the power used back to the overhead line.

The new locomotives are, of course, designed to work with all types of signalling systems and it is envisaged that, for East Coast Main Line operations, they will be fitted with AWS, TPWS and ETCS.

Each loco will have two pantographs, giving redundancy in case of failure, and also a ‘last mile’ diesel engine. This is designed to enable the locomotive to remove itself, and its train, from the main line in case of total power failure either on the loco or on the OLE infrastructure. The 400 litre fuel tank will be sufficient for much more than one last mile, and with a speed limit of 30mph it will allow the train to reach a convenient station rather than being stranded out in the countryside.

Design for this tentatively-named class 93 locomotive is well advanced and Bombardier are just waiting for a launch order before putting it into production at its Kassel factory in Germany.

Suburban improvements

While this Inter-City 225 upgrade / replacement is a design concept at present, another Eversholt Rail initiative is already underway. Greater Anglia runs 94 four-car class 321 trains which were built back in 1988 and, like the class 225s, are now getting tired. One of these units is being rebuilt in two formats, which will give an interesting comparison.

Two cars will be fitted with a completely new suburban-style interior. This will include air conditioning, new energy-efficient LED lighting, redesigned seats and two wheelchair spaces plus an accessible toilet. The original plan was to leave the windows as they were, but in fact they are now being replaced by sealed, double-glazed units.

The other two cars of the same train will also have the benefit of the air conditioning, new lights and windows, but the seating arrangement will be metro-style – designed for the commuter with slimline 2+2 seating, easy access and increased standing space.

Currently undergoing refurbishment by Wabtec in Doncaster, the refreshed train should run in service towards the middle of 2013. It will be interesting to hear passengers’ reactions to the two alternative interiors as their comments will influence what is done to the rest of the fleet.

It is estimated that the 94 trains will cost £70 million to refurbish to this standard, or £130 million if new traction equipment is included. This is a considerable saving over the £600 million which would be the approximate cost of a replacement fleet.

These projects, coupled with the refurbishment to a class 317 that is being undertaken by Bombardier at Ilford (reported last month), show that the rolling stock companies (ROSCOs) are committed to improving the standard of the trains they own without subjecting their operator customers to the cost of completely new trains. It is an intriguing initiative, and it will be interesting to see these ‘new’ trains when they break cover over the coming months.

Station design: Balancing function with aesthetics

17th January 2013

There is more to good station design than an impressive-looking building. It should also be more than a good place to catch trains – a recent ATOC (Association of Train Operating Companies) Interchange and Integrated Transport Conference stressed that train companies are committed to improving links with other forms of transport.

Station designers need to plan for crowd pressure, ease of passenger flow and general wear and tear. Access for maintenance and cleaning are crucial for longevity, security and safety and place special demands on material choice and engineered solutions. Good wayfinding is important, as can be read elsewhere in this issue, and provision has to be made for retail outlets, waiting areas, passenger drop-off and ‘kiss and ride’ zones.

Taking all these into consideration in a new station design is complicated enough. When an old, listed building is being remodelled everything also has to fit in with the layout of the existing structure.

Pleasing the crowds

Taking inspiration from how airport terminals have historically been designed, a new railway station needs to consider both passenger experience and flow to ensure long term benefits. The design of the new Crossrail stations, which together will have to handle 200 million passengers each year, is focussed on getting the internal design correct. Aesthetics have to be balanced with the performance qualities of materials to provide a durable finish which will last a lifetime.

Architectural metalwork can balance visual appeal with enhanced performance qualities and provide a highly functional solution. Wall panelling provides a durable way of handling crowd pressure while column casings can also incorporate impact resistance for vehicle movement. Sloping tops with 20 degree angles can be used to help prevent the surface being used for discarded rubbish or left luggage.

Refurbishment Waterloo

Many stations have stood the test of time and any modernisation will need to provide for similar longevity. However, upgrading and adapting the existing building fabric is not without challenges. Working on all three phases of refurbishment at Waterloo Station, SAS International collaborated closely with architects and mechanical and electrical consultants to design, manufacture and install architectural metalwork solutions to a strict timeline.

With 90 million passengers passing through Waterloo station every year, managing passenger flow was a key factor for consideration at the design stage. The programme for completion was extremely challenging and, with limited as-built information, the architects had to investigate the existing fabric, propose a solution and start manufacture – almost simultaneously. All this had to be accomplished with minimal disruption to the working station.

The refurbishment of the peak hour subway, for instance, created a modern, open space designed for increased capacity over the coming decade. This subway, which is accessed from the platforms, was originally designed to alleviate overcrowding at the main underground entrances to Waterloo Station. SAS International’s project management team worked closely with architects bpr on the design, manufacturing and installation of the architectural metalwork for this phase.

The civil engineering involved in opening up the arches was a major challenge. The lower subways are constructed from Victorian brick arches some 3.5 metres thick. Once the new openings were instated, the specially designed cladding had to be installed quickly and easily within tight time and budgetary constraints.

The demountable barrel vaulted ceiling had to incorporate existing services. A bespoke design was required for the existing brick and render arched soffit of the subway which contained congested services suspended beneath. SAS International provided a sub grid, spanning these services, to facilitate the suspension of the new ceiling. Twin vaults were added along the lengths of the subway to create a feature in the otherwise flat plane and to reflect the existing arches. The lighting and ceiling grids had to be co-ordinated with the structure of the lift valley to maximise ceiling heights caused by the low soffit.

Another phase of the redevelopment of Waterloo, a new £25 million balcony with ten retail outlets, opened in 2012. It was designed to reduce congestion on the concourse for 300,000 daily passengers and improve access to and from Waterloo East. It also provides passengers with an extra 20,000 sq. ft. of retail space. SAS International worked closely with BAM Construction designing solutions to encase services for future ease of access.

Versatile metalwork

Using architectural metalwork such as wall panels and column casings can transform both the look and the functionality of station buildings. At Liverpool Central station, light and space are priorities with walls being removed to increase the footprint of the concourse. SAS International powder coated steel cladding is being used with vitreous enamel in passenger areas to provide a robust finish.

Another example is the myriad of metal solutions which were designed, manufactured and installed by SAS International at Snow Hill Station in Birmingham. The building’s interior was fitted out so old meets new, creating a stunning combination of contrasting materials of brick against metalwork. An SAS International System 200 Waveform ceiling system in light blue was installed in the main lobby areas.

Not only did the design have to look good, the peaks and troughs of the ceiling had to be carefully calculated to coordinate with the heavy electrical services in the ceiling void whilst maximising the perceived ceiling height. SAS International produced a 3D model of the area to fully engineer the Waveform panels where they met perimeters and the vertical risers. The ceiling was mechanically secured using hold down brackets while access panels were fitted with safety chains.

Service risers in the lobby areas were constructed of curved, perforated, hook-on metal panels to conceal electrical services running vertically on the walls. They were scalloped where they interfaced with the waveform ceiling.

There are many ways to produce an aesthetic and functional design when undertaking a station refurbishment. Combining new metalwork with the features of the original building can result in visually stunning combinations of materials such as aluminium and brushed stainless steel coupled with original cast-iron columns and wrought iron girders.

Weathering the storm

The demand for innovative and interesting interior / exterior linking space must be balanced with the use of high performance products. It is not just a question of design aesthetics, the durability of the materials and ease of maintenance is essential to ensure the environment remains impeccable.

The open nature of a station concourse makes it subject to external temperature changes, so solutions manufactured from aluminium can provide long term solutions. For example, SAS International’s project management team has just finished installing a bespoke soffit lining at Blackfriars station in London, the first railway station to span the Thames. The potential of damage being caused to fittings from being exposed to the elements was taken into consideration so triangular aluminium panels were chosen, suspended internally and externally from the structural steelwork.

Long-term value

Off-site prefabrication can provide cost and installation efficiencies. It can ensure consistency of build quality, minimise risk and improve on-site safety. Project planning can also be improved by reducing delays caused by other trades coming onto site. Research carried out by WRAP (Waste and Resources Action Programme) has found that off-site construction generates up to 80% less waste than site-based building.

Communication is of paramount importance and essential for the success of these large scale projects. A manufacturer which can offer a design service from the outset can help substantially with evolving design plans and onsite challenges. Architects, designers, engineering firms and installers have to work as a team.

Signalling suppliers take note!

16th January 2013

For the last six years, Network Rail has staged nine one-day seminars with suppliers from the signalling industry to brief them on the engineering and technical developments that are taking place and to get feedback on the issues seen as pertinent. The 2012 event took place recently in Glasgow, so the rail engineer ventured north of the border to sit in on the discussions.

In opening, Mark James, the head of Engineering Signalling in Network Rail, recalled that the company has now been in existence for ten years and, in that period, much has happened in the way the rail infrastructure is managed with many implications for signalling.

The concept of a ‘Signalling Industry Partnership’ has come about and, in Control Period 4, 9,300 Signalling Equivalent Units (SEUs) have been renewed, 2,400 SEU re-locks or re-controls have happened and 1,500 SEUs are now commissioned using the new modular technology. However, signalling costs are still considered to be too high and a real reduction of 16% is the target by 2019. The ‘cradle to grave’ time to develop and implement signalling projects is far too long; the Network Rail chairman has been surprised by the old methods used in the signalling profession. Hopeful signs are there to get practices modernised: plug and play cabling, lightweight signals, signals on OLE structures, 3D mapping, paperless testing, intelligent scheme plans. Acceleration in project delivery is the first priority; innovation and new technology will be secondary to this.

Power distribution and cable types

Signalling systems require reliable power supplies, both in equipment rooms and at the lineside. A new generation of trackside power units – switchgear, transformers and distribution units – has emerged in recent times to complement the predicted growth in new signalling schemes. The increase in power demands can probably only be achieved from an extended supply chain.

A major part of power provision is the associated extensive cable network. Traditionally, this has been copper based, an increasingly expensive metal. Some reduction in need has been achieved by using two instead of three-core cable, as is reported in our previous issue, but replacing the expected demand for one million kilos of copper with something else is the challenge.

The solution, according to Tahir Ayub from Network Rail, is aluminium. This is an abundant metal that is theoretically 100% recyclable without loss of characteristics. It is £2,000/tonne compared to copper at £8,000/tonne, but needs a bigger core size for the same conductivity. Nonetheless, a saving of £8.50 per metre is possible giving a saving of around £400,000 per project.

Downsides are few: location cases will need some re-design as the cable is harder to bend and an increase from 650V to 1000V for the main signalling distribution feeders might be necessary. In addition to cost reduction, there are considerable other advantages. Using a stranded cable, unarmoured but with a jelly fill, will yield a huge reduction in weight thus permitting bigger drums and more hand pulling. Bolted rather than compression terminations are coming out as favourite. The business and technical case is in preparation and looks promising. Equally, signalling equipment designers can help by removing peak load surges, point machine design being a good example.

Records, drawings and data

The acquisition, processing and retention of records and other data has always been a challenge for railway engineers, and signal engineers in particular. Laborious, paper-based information was for long the order of the day and even the introduction of CAD tended only to replicate the paper procedures that had gone before. It is evident now, however, that much more imaginative use of computers could thoroughly modernise these outdated methods.

Signalling scheme plans are one such example and Ken Peters from Network Rail described how the Signalling Tools and Method Programme (STAMP) is revolutionising the production of such plans. Begun in 2005, the system has now matured and trial usage has been in place since 2010. The programme focuses on the structure of asset data rather than producing drawings by capturing the detail of a 3D design within a geo-spatial cross-disciplinary approach which models and simulates the working railway environment. Such designs are to use a common Signalling Data Exchange Format (SDEF) that will eventually become mandatory. The concept of automatic image recognition using video collected from a track recording unit in the Cardiff area has been trialled, and from this information new assets can be inserted into the resultant maps.

Once it has been collected, validating SDEF data needs computer-aided assistance. Jennifer Whittlesea from Selex explained how a self-contained website application can be used which allows the processing of SDEF XML files including the conversion if they were created in different versions. From this, the system will determine whether an SDEF design is valid for its intended new application. Examples are the headway analysis tool that will look at intended train service patterns and a facility to see if existing rules for scheme plans are pertinent or relevant. From all of this, asuiteofrulescanbebuiltupbyuseofa graphical editor.

Collecting data is one thing, controlling access to it is another challenge. Eddy Locke, from Network Rail’s data collection services, explained some of the considerations that must take place. To ensure data quality, the following tests have to be fulfilled: does the data have an owner, can the data be maintained, who collects the data, how is it collected, and how accurate is it?

Thirty-five terabytes of data are collected each year from various sources including the measurement trains, radio surveys and
manual methods. The Network Rail data centre at Milton Keynes is upgrading its storage capacity to 140 TB but the key will
be to analyse, decide on relevance and distribute data to the right people. The ORBIS project (as mentioned in issue 98, December 2012) is part of this. As well as being better informed, the project will reduce the number of staff required out on the track, give greater assurance on asset safety condition, and lead to faster remedial work when problems are detected, e.g. broken rails.

Paperless testing

The time honoured way of testing new signalling installations, with its multiplicity of drawings and paper tick sheets, is in need of modernisation. Neil Porter from Atkins explained how this can be achieved – not by altering the process of testing but the way in which it is recorded.

A tester is provided with a mobile device onto which are downloaded the test sheets and test logs. Structured on a central Atkins WAN (wide area network), ‘bluebeam’ software will open up the relevant drawings on the device including all the normal tester ‘marks’ that would expect to be found. The testing activity takes place in the usual way after which the drawings are ‘flattened’ to roll up all the tester’s marks into a pdf file. The files are sent to the original design house from which a new set of task sheets will be prepared by a tester in charge, who will continually review the test sheets to assess progress and credibility. From the revised test logs, the tester can determine the extent of any re-test after which the logs are updated and final test certification achieved.

The process has been successfully tried on a number of small schemes with minor problems of software compatibility identified. Use is intended for both in-house and agency testers. It is, however, dependent on good communications to the test site as well as a robust IT system to ensure continuity of data. Hourly updates of data from WAN to LAN (local area network) would be good practice.

‘Plug and Play’

The idea of having pre-formed cables which can be plugged together and into equipment terminations is attractive as it can save many man hours in the task of cable installation. But is it practical? Graham Thompson described the setting up of a trial site at Leicester that can simulate real trackside conditions. Cable routes, undertrack crossings, power cubicles, main and shunt signals and 2 & 3 door location cases, all replicating a typical signalling installation, have been provided.

Pulling the plug-coupled cables through an undertrack crossing is the biggest worry, especially if they are already in use and partly filled. Nonetheless, the trial has proven the concept. Key will be the accurate measurement of the plug coupled assemblies which have to be precisely the right length. Installation time is significantly reduced and signalling projects can be expected to call for this technology in the future.

Level crossings and obstacle detection

Despite the extensive usage of AHB and AOCL level crossings, a significant number of controlled barriers exist on the UK rail network. Many of these utilise CCTV surveillance so that the signaller can check the crossing is not obstructed before the approach signal is cleared. Can the surveillance task be automated?

It fell to David Jones from the Network Rail signal design group at York to describe how obstacle detection technology can achieve this. Two detection systems are required – RADAR (radio detection and ranging) and LIDAR (light detection and ranging). The RADAR needs detectors at each of the crossing corners to provide reference points for the four RADAR sensors.

These will provide a continuous‘picture’of the crossing and can compare to the reference. However, RADAR cannot scan down to ground level and would miss a person lying down. Thus the LIDAR system is also employed using both high and low beam scanning lasers. Two LIDAR units are required, oriented towards each other.

In operation, the strike-in point is at the signal showing green before the crossing control signals, whence the entrance barriers (the left hand ones) will lower. If the obstacle detection system then determines the crossing is clear, the exit barriers (the right hand ones) will lower. If, however, an obstacle is detected, the exit barriers are held for a further ten seconds. In the event that, after this period, an obstacle is still detected, then the barriers will lower but the controlling signals will not clear. The exit barriers will then be raised again to allow anything trapped to escape. This sequence continues and only when an obstacle is no longer detected will the signal clear. Video cameras and recorders will monitor the events, these having number plate recognition equipment and backed by inductive loops in the roadway to identify rogue road users.

Three such crossings have been installed as a trial between Ely and Norwich as part of the modular signalling project and further installations between Crewe and Shrewsbury and at Llanelli were in place by the end of 2012. Training courses are in preparation and signalling installation and testing manuals are being updated. A framework supply contract is in the offing. This looks like being a standard feature for such crossings in the years to come, thus saving the cost of conventional CCTV installations and signaller time.

ERTMS

The Network Rail update on progress with ERTMS, as given by Carine Marin, came across as very positive but perhaps somewhat over- optimistic. The Cambrian ‘early deployment scheme’ (in other words – a trial) is now fully operational and many valuable lessons have been learned. The claim that ERTMS will yield lots of extra capacity has yet to be borne out and it must be remembered that other, more modern designs of train control system have emerged since the development of ERTMS commenced nearly twenty years ago. The biggest on-going constraint is the lack of data capacity on the GSM-R bearer and experience in Europe has shown that the system is incapable of being used in high traffic areas such as big terminal stations.

The radio problem is one that needs to be addressed urgently at a European level and, whilst the solution of moving to 4G is often advocated by the mobile radio industry, no practical solution has yet emerged as to how this would be achieved in practice on an operational railway. The migration path from GSM-R and the avoidance of huge amounts of additional cost need to be part of any plan.

Network Rail would be well advised to critically examine their ERTMS promotional video and re-format it so as to give a realistic forecast on what ERTMS can and cannot do. Raising expectations that turn out to be false could lead to severe embarrassment at a future date.

Other initiatives

DeltaRail continued its promotion of IECC Scalable and its first deployments at Cambridge (for the Ely – Norwich scheme) and at Harrogate. A full account of this latest control centre product using message broker technology was given in issue 92 (June 2012) and it looks to have a big future on Network Rail and elsewhere.

The work of the Railway Industry Association was described by Francis How, its technical director and currently the IRSE President. Now 135 years old, the RIA is a trade organisation with a whole range of members – big, small, specialist and general. It sees itself as being supportive to Government, Network Rail, LUL, TOCs, Roscos and others on projects, but additionally promoting innovation, export, skills development, standards evolution and safety policy. The forthcoming rail technical strategy focussing on the 4Cs (cost, capacity, customers and carbon) might equally well apply to careers, competence, capability and collaboration, and the RIA would wish to be at the forefront of all these.

Altogether, a fascinating day where all the suppliers present will have learned something. Network Rail should be congratulated that it takes the time and trouble to brief the signalling supply industry on the latest developments and to encourage co-operation in the sector. Equally, it should be mindful of the feedback it receives from events like this and be prepared to make changes where it would be beneficial to do so.