It has long been recognised that the provision of drainage in permanent way work is a vital factor in ensuring the effectiveness and long-life of ballast. Recently, designers have put a greater emphasis on good drainage design. This has resulted in product development to ensure that not only is any drainage system guaranteed to perform its primary function but that it offers advantages in terms of speed and safety of installation.
Draining Swiss track
A good example of this new product development was seen recently at Lake Thun in the Bernese Oberland, Switzerland. Here, BLS Netz AG operates a rail network spanning more than 900 km. Direct proximity to Lake Thun and Lake Brienz as well as minuscule differences in altitude regularly cause the groundwater level to rise and penetrate the track bed. After more than 30 years of service, it was decided to renew the railway line. In parallel with permanent-way renewal, the existing drainage system – made of concrete pipes in an open drain trench along the railway line – and the cross drainage to a navigational canal also had to be modernised. According to the requirements of RTE 21110 (Swiss Railway Technical Code of Practice governing requirements for roadbed and ballast), the piping system required for railway line drainage in the roadbed and ballast has to meet the figures specified by the operator, e.g. a clear water inlet opening of at least 100cm² and a minimum slot width of 6mm. To ensure reliable operation of such a drainage system over a period of decades, demanding static, dynamic and mechanical requirements also have to be met. The gradient requirements are 0.65 to 11.05 per mil.
This construction project was realised with Simodrain® drainage pipes with an outside diameter of 250mm, SDR (Standard Dimension Ratio) 21, and 10mm slotting, specially developed for traffic route drainage by local company Simona. These extruded smooth-wall pipes meet the requirements of such a system, and with their large water inlet area they are capable of handling the specified 100cm. Using a special slot geometry and slot arrangement, and with the excellent hydraulic properties of the polyethylene (PE) material, the drainage provided by the system is ‘best in class’ and designed for the long term. End-milled slotting avoids undercuts, and hence deposits and incrustations. In addition, the pipes are easy to rinse out, making them the perfect solution for the Swiss railway infrastructure operator.
In the UK, Burdens, who have been involved in drainage since the company was founded in the 1920s, is currently working with Network Rail to introduce the Simona range of heavy-duty solid-wall PE pipes for use in pressure zones and critical track drainage applications.
Catchpits
Installing catchpits, a traditionally time-consuming process, is another area where new thinking can pay dividends. Now Cubis Industries, a company with three manufacturing sites in Ireland and the UK, has developed the STAKKAbox Ultima access chamber. This is claimed to have numerous advantages over existing systems, particularly as regards speed of installation. Indeed, because the chamber comes complete to site, they can be installed in as little as 18 minutes by a two-man team. Other advantages are a loading strength of 12.5 tonnes, high chemical resistance, and design flexibility. Manufactured from recycled materials, the chambers offer a high level of safety in installation and use, all of which makes the product very cost-effective. Cubis drainage catch pits are approved by Network Rail and by Manchester Metrolink, and supplied in the UK by Burdens.
Concrete Cloth
Another innovative product, which has been mentioned in the rail engineer before, is so-called Concrete Cloth, a flexible cement-impregnated fabric that hardens when hydrated. It comes in a roll format with a PVC waterproof backing and has been used on several Network Rail contracts where a traditional concrete pour would have been difficult. This flexible, strong and durable material is also easy to lay, allowing around 400m of ditch to be installed in one day with minimal staff. Concrete Cloth has achieved a Euroclass B-sl fire rating.
In September 2009, a 140m section of ditch was lined using Concrete Cloth by Amalgamated Construction (AMCO). The project was commissioned by Network Rail to provide drainage at the top of a railway embankment in Chipping Sodbury, Gloucestershire. This was the first time AMCO had used this product for ditch lining and the project was heralded as a major success. Concrete Cloth proved significantly quicker and easier to install than conventional concrete slab construction, reducing the project cost and time on site. The cloth was supplied in portable rolls for ease of use on a site with limited access. Andrew Gurd, construction manager for contractor Amalgamated Construction Ltd, said “Concrete Cloth is incredibly quick and easy to use. It allowed us to line over 100m of ditch in less than 8 hours, with the minimum of manpower and plant.”
Installation begins with digging a V-shaped ditch with smooth, flat sides. Concrete Cloth can be supplied by Burdens either in man portable-lengths (8 linear metres weighs 105kg) or in large rolls (120m, 1400kg) if the necessary plant is available. Once unrolled and positioned, the cloth is hydrated by controlled spraying with water – even sea water may be used – with care being taken to avoid washout. An excess of water should be used as Concrete Cloth cannot be over-hydrated. Once hydrated, it remains workable for about two hours, although warm ambient temperatures may reduce the working time. It hardens to 80% of its 28-day strength in 24 hours and is ready for use.
Drainage products may be largely hidden from view, but that doesn’t mean that innovation is not taking place. After all, every high-technology engineering project needs good drains…
The Welsh Government placed a £35 million contract in December 2009 for the construction of 5.3km of new road taking the A487 around the towns of Porthmadog, Minffordd and Tremadog in North Wales.
A joint venture (JV) partnership of Balfour Beatty and Jones Bros Civil Engineering UK was asked to construct a 7.3m wide carriageway on the flood plain of the River Glaslyn to the north of the Cambrian Coast mainline railway.
Along with sub-contractors Balfour Beatty Rail and Cleveland Bridge UK, the JV has built 8 new bridges, a number of smaller structures and a considerable length of embankment to create the substructure for the new road.
450,000m³ of fill, weighing about 900,000 tonnes has been used on the project. It was sourced from the adjacent Minffordd Quarry and transported direct to site by a network of haul routes. As a result, 106,000 road wagon movements were avoided on the existing highway network.
Four railways
Four different railway lines have been affected by the work. The obvious one is Network Rail’s Cambrian Coast line, the line of the bypass running close to it over much of its length. Also involved are the Ffestiniog Railway (FR), the Welsh Highland Railway (WHR) and the Welsh Highland Heritage Railway (WHHR). The FR is well known.
The WHR is the relatively newly restored and reopened heritage line operated by the FR. It runs from Caernarfon on the route of the former Welsh Highland line for most of its length, but deviates from it at the Porthmadog end to join into the Ffestiniog Railway’s Porthmadog Station. The WHHR is a separate, shorter heritage railway that operates on the original line of the Welsh Highland through the Porthmadog area.
The Cambrian Line was the most affected by the new bypass. 850m had to be realigned by up to 25m onto a new embankment built alongside to make way for the new road. A new 3-span viaduct carrying the bypass across the River Glaslyn is only about 50m upstream of the railway river bridge.
In addition, a bailey bridge was built over the river above the new viaduct site to carry the haul road. Where the road and rail routes run side-by-side, new bridges and culverts were built beneath the road connecting with existing equivalents under the rail line.
Finally, a level crossing providing the existing road access into Minffordd Quarry became redundant as the quarry will in future be accessed from the new bypass.
Shorter route
The realignment necessitated first the construction of a new rail embankment, then the laying of new track onto it. Track installation was carried out by Balfour Beatty Rail. On 7/8 May this year the line was closed and bus substitution services took over whilst the existing line was cut and slewed over at each end of the new embankment and connected to the new tracks. This raised an unexpected issue, for the JV at least.
The Cambrian Line is the site of Network Rail’s ERTMS trial, and the new railway is actually about 7m shorter than the old alignment. Network Rail’s signalling team recognised the significance of this and updated the ERTMS system software for the route before the line was reopened after the diversion.
Bats
At Minffordd Quarry the old level crossing was removed, since, as already mentioned, access to the quarry was to be diverted via the new bypass.
Nearby, a small drainage culvert passing under the original railway route had to be replaced by one under both new road and rail embankments. However, the environmental requirements for the site dictated that a large structure be built with sufficient headroom for bats to fly from one side to the other, so what was originally a culvert a few hundred millimetres in diameter has now become a significant structure.
Apparently this is not the only such example on the route of the road, and some culverts are “almost high enough for a double-deck bus”!
Earthworks operation. Photo: the rail engineer.
Hydraulic modelling
The Cambrian Line was also affected by construction works and plant operations in other ways. At the river crossing, construction upstream of the piers of the new road bridge and of the temporary bailey bridge could have had an effect on the river bed and the foundations of the rail bridge.
Network Rail insisted upon hydraulic modelling before work began, and regular monitoring of the river bed and rail bridge foundations throughout the works and after completion, to ensure that there was no risk to their structure. Given the Glanrhydd accident in the 1980s when 4 people died as the result of the scouring away of the foundations of a rail bridge, their concern is understandable.
One of the largest crawler cranes in Europe was brought in for the construction of the permanent river bridges. This 630t monster was quite large enough to affect the adjoining railway should there be any mishap during its use, and so detailed methods of working were agreed with Network Rail beforehand.
The same procedure was adopted elsewhere when cranes or similar plant were to be used where they might affect rail safety.
Ffestiniog Railway
A new bridge carries the Ffestiniog Railway over the new bypass. It was constructed alongside the line on temporary trestles by Cleveland Bridge. In January 2011 the JV was given a 4 day line closure by FR during which they built the concrete abutments of the new bridge and dug out the “plug” of soil from between them.
On 7 February the deck was slid into place on the abutments and within a week the complete structure was handed back to FR. Track was relayed over the bridge while additional works were carried out on either side, including the remodelling of Minffordd Station and double-tracking through it. The first train crossed the new bridge on 2 March, only 6 weeks after the line was closed.
The FR gave the JV a great deal of co-operation, including an agreement for a temporary level crossing at Minffordd. Manned by a JV employee who was trained as a crossing keeper by the FR, this plant crossing allowed the removal of 10,000m3 of material, cut out of the existing ground due to the differential level between the rail and new road levels, without the use of any public highways, a great benefit to the local population.
Welsh Highland
In contrast, the new road crosses over the route of both the WHR and WHHR. A site for the new bridge was chosen where the 2 lines lie close together. The structure is a 3-span design, also fabricated and erected by Cleveland Bridge, while its concrete substructure was built by the JV.
The two railways pass through the bridge’s centre span, the side spans allowing access for both the local landowner and for future highway maintenance. A temporary level crossing over both rail routes was established at the site and the WHHR insisted on a different approach here from that taken by the FR at Minffordd as the line was to remain open during the works.
A WHHR employee was used as crossing keeper, and gates, traffic lights and a telephone were all provided for his use. A concrete slab formed the crossing surface, and one of the duties of the crossing keeper was to ensure that the flangeways in this were kept clear for the passage of trains.
Environmental matters
The Environment Agency was heavily involved in the project, especially regarding the Glaslyn river crossing, and so were other environmental organisations, archaeologists and wildlife organisations. All placed constraints and requirements upon the construction team with provisions being made for the protection of reptiles, bats, badgers and birds.
Virtually the whole of the site lies in the flood plain of the river and this too also caused complications. All these issues, and the need to liaise with the four separate railway companies involved, required careful and detailed pre-construction work planning and agreements.
View of both the bypass and Cambrian Line from Minffordd quarry. Photo: the rail engineer.
Local involvement
Both Balfour Beatty and Jones Bros are rightly proud of their liaison with the public throughout the contract. They have held regular meetings with local councillors to give them advance notice of works and established a visitor centre close to their own offices.
This provides information about current works and future plans and is open every working day. Even a large print of the route map with appropriate captions placed in the window of a local Tesco has proved popular.
The project team has supported local charities and allowed the mountain rescue team to use the visitor centre in the evenings as a training room. They have consulted local stakeholders about the appearance of the structures on the road, and have sought the views of the relevant railway companies about the colour and appearance of the new rail bridges.
When, in response to a number of accidents and incidents across the railway network, there was a local campaign about level crossing safety, the contractors joined with the FR to work with IoSH and a local organisation called “Working Well Together” on a two day event. It included a practical demonstration on FR premises which highlighted the real danger to people of misusing a level crossing.
The new Porthmadog, Minffordd and Tremadog bypass is due to open in December 2011. On completion, it will represent a true joint venture between the two main contractors and four railway companies. There aren’t many projects like it….
On the south bank of the Thames, opposite Victoria station, sits the sprawling, disused site that houses the well-known landmark Battersea Power Station. Alongside is the smaller but just as well known Battersea Dogs & Cats Home.
Between the two are the Up and Down Fast and Reversible lines to Chatham from Victoria that pass over the Battersea reversible line, the Up Stewarts Lane line and two sidings.
The structure that carries the Chatham lines over the others is known as the Brighton Goods Bridge No. 6. The bridge is an impressive and complex five span intersection bridge with skews that vary from span to span.
The bridge was constructed in 1913, just before the First World War. The construction of the deck for each span consists of wrought iron longitudinal girders, cross girders and rail bearers. The up and Down Chatham lines are both supported on cross-sleepered track on longitudinal timbers, whereas the reversible line runs on wheel timbers.
Major investment
The longitudinal girders span between padstones supported by brick piers and masonry abutments. The main girders are discontinuous over the intermediate piers allowing each span to behave independently.
The structure is hemmed in by the Dogs’ Home and the power station and although there have been many false starts with schemes to rejuvenate the power station site, there is now a growing certainty that a new £5.5billion scheme will transform the location.
The underlying concern for Network Rail is that if the scheme progresses, access to their Brighton Goods Bridge No. 6 is likely to become even more difficult so now is the ideal time to carry out any remedial work that may be necessary.
For many years, structures with timber decking and wheel timbers have created significant challenges for the maintenance teams involved. Previous assessments undertaken by Atkins Rail in 2004 concluded that the structure was generally sound but that the cross girders limited the route availability of the structure.
Network Rail had decided that at such an important location, any new structure would have to comply with full RU loading. Therefore, knowing that train disruption had to be kept to an absolute minimum, Tony Gee & Partners, design consultants, prepared various preliminary schemes for Network Rail to achieve this objective.
Subsequently, these schemes have been developed into more detailed options by the current designer, Mott MacDonald, and BAM Nuttall has been invited to undertake this project as part of their 5 year Framework Contract with Network Rail. The work is valued at approximately £7.6m.
Christmas blockade
The innovative design that was chosen included the need for regular weekend possessions and sequential blockades of the rail filled Spans (3, 2 and 1) leading up to Christmas 2011 and then, from Christmas Eve, a 9 day blockade, closing all lines for 3 days and then the top three Chatham lines for a further 6 days.
Work started on site in the spring of this year and there are currently about 50 operatives working day shifts, 7 days a week. From the start of August the workforce will double and the site will become operational round the clock, increasing the momentum of activity that will continue right up to the Christmas blockade.
Animal welfare
However, before any real engineering work could start, a significant number of dog kennels, exercise areas and recognised dog walking routes had to be relocated. Two weekly liaison meetings were organised with the Dogs’ Home to ensure that the walking routes for the dogs were realigned well in advance.
A cattery had to be relocated as well and buildings demolished, and a number of health & safety issues had to be addressed relating to the proximity of the animals.
Contaminated ground conditions, created by man as well as animals, had to be managed, a “super highway” constructed for a cluster of important and potentially dangerous cables, and an ordnance survey undertaken to ensure that there were no nasty surprises still lurking around from WW2 .
Span 5 base construction in Battersea Cats & Dogs home.
Concrete Box design
The design chosen is interesting and demands a significant level of site ingenuity. An in-situ reinforced concrete box will be constructed in each span with the top at the level of the soffit of the existing superstructure.
These concrete box structures will be different for each of the five unique and individual spans and must be completed before the Christmas blockade.
The new reinforced concrete boxes are designed to carry the required rail loading so when the existing superstructure is removed, no additional strengthening is required. This removal will take place during the Christmas blockade using a large mobile crane.
The newly exposed top face of the concrete box girder that this will reveal will then be made waterproof. A suitable drainage system will need to be installed and 3,000 tonnes of new ballast imported by an end discharging ballast train provided by Network Rail.
New track will be laid across the five spans for all 3 lines, top ballast placed and the track aligned, stressed and tamped ready for the demanding post-Christmas timetable.
That all sounds quite straight forward, but the tricky bit is how do you create a structure from concrete in-situ, within a bridge, whilst avoiding too much disruption? This is where the on-site skills of the site team have been tested.
The project has identified five key milestones leading up to the Christmas blockade, one for each span. Span 4 cuts across part of the Dogs’ Home so, as there is no railway under the bridge, this span was used to try out the proposed method of working and became the first milestone.
This was followed by Span 5 which was in progress when this article was written. Spans 3, 2 then 1, are programmed for September to December.
Method of working
Concrete was poured to form the base slab to span 4 in March this year, followed by the construction of the side walls. A polythene membrane was inserted between the existing abutments and piers and the new concrete forming the walls to enable them to act independently.
Reinforcement couplers were cast into the walls approximately a metre below the soffit of the existing superstructure. These were designed to receive the connecting reinforcement bars that would extend down vertically from the top slab of the box girder.
So far, it was all relatively straight forward. The real challenge was how to construct the top section of the concrete box to enable it to fit directly below the soffit of the existing superstructure whilst minimising disruption to trains.
Bob Snow, Project Manager BAM Nuttall, explained to me how they addressed this challenge.
With the invaluable assistance of their sub-contractor Kilnbridge Construction Services, and especially their Pre Construction & Engineering Manager, Plamen Petkov, three tables were constructed onto which a substantial 32mm diameter reinforcement framework was fixed to form the top section of the concrete box.
The tables were supported on trestling so that they were at the correct required height for installation. Wheels were fixed to the base of the supporting trestling and angle rails bolted to the base of the new concrete box.
Then each table in turn was moved into its final position using Turfers and the reinforcement coupled together to form the roof of the concrete box. Intermediate staging enabled the vertical reinforcement to be coupled to the side walls.
Wall and table construction. Photo: the rail engineer.
The devil is in the detail
We have to remember that no two spans are the same so the challenge for the Kilnbridge steel fixing team is substantial and the devil is definitely in the detail.
So far the technique is working well and during a 24 hr possession of the Chatham lines, the timber walkway decking was removed exposing the reinforcement, 2 concrete pumps were installed alongside the structure and over an 8 hour period a 300 cubic metre concrete pour was successfully completed. It is proving to be an effective method requiring substantial on-site skills. Only four more spans to go!
In times gone by, the area around the power station was used as a water treatment plant so the ground conditions are a little suspect, especially around spans 1 and 2. Four piling rigs have been brought to site to be operated by Keller Geotechnique.
They will install over 150 reinforced concrete piles over 12 weeks during weekend possessions to strengthen the existing ground foundation within the spans. The piles will vary from 300 to 450mm dia. and will be founded into London clay ranging from 18-22m below ground level.
The work so far is going well. The technique they are using to cast a bridge within a bridge, five times, is proving sound. The plan is to ramp up to round the clock working so that everything will be ready for Christmas when the old five span superstructure is removed.
The train operating companies involved understand and support the overall plan. The dogs and cats appear to be taking everything in their stride and there is no evidence of stray paw marks in newly cast concrete.
It is estimated that a total of 1,100 tonnes of reinforcement and 4,500 cubic meters of concrete will be used. There will be ballasted track in place which will be much easier to maintain. The structure will have adequate clearances and walkways to provide a safer environment.
By the New Year, trains will be running over the reconstructed Brighton Goods Bridge No 6 and Battersea’s famous animal residents will no longer have their walks interrupted.
Providing accurate, understandable and timely information to the travelling public is an ever present challenge. Described once as not a can of worms, more a bucket of snakes, this is a fairly apt description for the task.
Anyone who thinks it is easy has no concept as to what is required or how it should be done. The recent hard winter with large amounts of snow demonstrated the problem all too clearly.
Train services were inevitably disrupted and particularly in the politically-sensitive electrified third rail areas of the former Southern Region.
Here the massive build-up of snow and ice on the conductor rail made it a huge challenge just to keep trains moving, let alone providing accurate information as to which services would be operating. It is rarely as bad as this, but even minor disruption can present a significant challenge to the flow of train running information.
So why is it so difficult and what can be done to improve things? the rail engineer talked with Chris Scoggins, the Chief Executive of National Rail Enquiries, part of the ATOC sphere of operations, to find out.
Old and Emerging Requirements
The occasional train traveller usually associates passenger information as something that he / she acquires from the Internet to look up train times and fares prior to making the journey and at the station to get confirmation of train running and platform.
These two elements remain vitally important and the accuracy of the information at this stage can have a significant impact on the perception of rail travel. The classic engineering terminology of right and wrong side failures just do not apply in this scenario.
Wrong information given out is as damaging as not having any information at all; indeed some would argue that displaying wrong messages is worse than showing nothing.
The seasoned traveller, however, increasingly wants much more than this. The advent of mobile phone networks and on-air data provision has meant that personalised information for the planned journey should be capable of being given out both prior to journey commencement and en route.
Any disruption that would cause the journey to be modified should be advised by text message or email direct to the person’s mobile device, be it laptop, iPhone, Blackberry or mobile telephone. With this upping of the facilities comes the need for even greater accuracy so that the intending traveller can modify their day’s schedule with confidence.
Information Sources
The railway operates to a timetable and from this it should be possible to derive data that is capable of being fed to all users who promote and publicise train travel.
However, as in all modes of transport, the delay and disruption that can occur will cause the timetable to be deviated from in both planned and unplanned situations. It is during these times that information provision is at its most important and it has been a challenge for the rail industry over many years to get accurate updates to the running of services collated and distributed to those that need to know.
Enter the Darwin concept – an initiative and development by the Train Companies, ATOC and Network Rail to get much greater accuracy in the compilation of train information data and the distribution of it to a widening user community.
Described as a Real Time Train Prediction system, Darwin draws data from a number of sources, assesses the information and then intelligently predicts what this will mean to the ongoing train service. The sources are:
Integrated Train Planning System (ITPS) – this is the Network Rail basic timetable, which is compiled twice a year but updated every 24 hours and distributed every night to all rail companies and external bodies that require timetable information
TRUST (Train Reporting Using System TOPS) – a system that logs train movements and timing at selected passing points on the network, distributing the report to train and network control offices
Train Describers (TDs) – the part of the signalling system that informs signallers of the identity and whereabouts of every train on the control panel with all berth steps (real time train movements) being available as a data message
Control Room Information Controllers – known as the Tyrell system that is used to provide structured messages to TOC staff on cancellations, short train formations, etc.
Some CIS control desks where train departure updates are decided locally
Darwin Workstations – provided in the National Rail Communications Centre (NRCC) and in TOC control offices where direct input to the system can be made.
All these information packages are sent to Darwin as they happen so a high number of data messages are constantly being received.
What does Darwin Do?
The success of any traveller information system will lie in its ability to predict the future to a high degree of accuracy. The algorithms of Darwin are designed to:
In mid-August, Balfour Beatty Rail invited Network Rail, key rail consultants and members of both the Westminster and Holyrood parliaments to take part in their first Open Day to celebrate the opening of their permanent office in Shettleston, Glasgow.
The full spectrum of rail disciplines were showcased including representation from other parts of the Balfour Beatty Group including Plant and Fleet Services, Regional Civil Engineering and Engineering Services giving delegates the opportunity to meet and discuss all of their rail life-cycle requirements from concept to delivery.
Interesting kit
Several interesting pieces of equipment had been brought in especially for the day.
One of the brand new B41UE Matisa Tampers, part of Balfour Beatty Rail’s recent £20m investment in new plant, had been specially transported all the way from Cambridgeshire, and the recently approved Air Insulated Switchgear, detailed elsewhere in this feature, that will be trialled on the Paisley Corridor project was brought over from Balfour Beatty Rail’s base in Offenbach, Germany.
There were a number of other items of plant on display as well. A Front Shovel Excavator, Base Ballast Hopper, Unimog, Top Ballast Hopper, Doosan and an Ultrasonic Flaw Detection RRV all attracted interest.
Address
Peter Anderson, Managing Director of Balfour Beatty Rail UK, in an address to the delegates, spoke of the Group’s work in Scotland, and specifically important rail projects such as Paisley Corridor Improvements, Glasgow Central Station, Gourock Station, Airdrie to Bathgate Rail Link, Edinburgh Waverley Station and the Forth Bridge, emphasising the benefits of the projects for the local communities.
Innovation – Air Insulated Switchgear
As one of the exhibits, Balfour Beatty Rail GmbH in Germany showcased their Air Insulated Switchgear. The Rail Engineer has already reported on a solid conductor beam system for overhead electrification (issue 66 April 2010).
Since then, Balfour Beatty Rail has introduced Air Insulated Switchgear (AIS). This has been designed specifically to meet the requirements of 25kV 50/60Hz railway applications and is derived from conventional 3-phase switchgear.
The Balfour Beatty Rail AIS TracFeed TAC switchgear is developed for use with single phase (TAC1) and two phase (TAC2) railway applications serving all AC feeding systems such as conventional, booster and autotransformer.
It is common for switchgear used for 25kV railway applications to be insulated using SF6 gas (Sulphur Hexaflouride). This is a better insulator than air, so that the gaps between components can be reduced while still avoiding arcing.
However, SF6 is a “greenhouse gas” as defined in the Kyoto protocol. This leads to restrictions both in manufacture and disposal of the gas. Specifically with regard to switchgear, the equipment has to be monitored 24/7 as any leakage will not only cause the equipment to malfunction but will also result in an environmental incident.
Clever design has allowed Balfour Beatty Rail to utilise air insulation. This provides a product that conforms with current environmental requirements and is also easily extendable – there is no longer the need to bleed off SF6 gas, make modifications, and then refill.
First introduced on the continent, the initial trial site for the new switchgear in the UK is at the Paisley Gilmour Street TSC (Track Sectioning Cabin). The requirement for a single circuit breaker provides an ideal opportunity for the trial site at Paisley.
Airdrie-Bathgate electrification being installed. Photo: the rail engineer.
Initiative – Overhead Line Training School
Apart from the high-profile announcements of electrification in England, on the Great Western main line and between Manchester and Liverpool, there has been a quiet surge in electrification projects in Scotland. The new Airdrie-Bathgate route is electrified, as are the new lines on the Paisley Corridor Improvement Scheme (PCI). And shortly EGIP (Edinburgh-Glasgow Improvement Programme) will be starting – and that is electrified.
So Balfour Beatty Rail has identified that there is a skills shortage for electrification specialists in Scotland. The company already has an overhead line training school at Kirkby on Merseyside, and drawing from that expertise they will shortly be opening a new training span at Shettleston.
Balfour Beatty is currently speaking with local schools and colleges and the new facility will be open in March 2012.
The current PCI OLE team will provide many of the skills required to run the programme and several current projects are only a few miles away. Balfour Beatty Rail fully intends to bridge the skills gap in Scotland in preparation for the electrification projects coming up over the next few years.
Shettleston Community Growing Project (SCGP)
Another key purpose for the Open Day was to reinforce Balfour Beatty Rail’s commitment to the community, the latest being the Shettleston Community Growing Project (SCGP).
A resident-led initiative in the heart of Shettleston, the Project has instigated the transformation of a derelict site into a multi-use space for residents, community groups and local schools and will help reduce carbon emissions by some 1,286 tonnes a year. For every Open Day delegate Balfour Beatty Rail will be donating £10 to this wonderful project.
Peter Anderson commented, “Today has been about celebrating the opening of our new office here in Shettleston, once again showing how committed we are to supporting Network Rail, Transport Scotland and local communities.”
Key current projects
As the day unfolded, Balfour Beatty Rail teams were continuing to put that commitment into practice by way of a number of ongoing multidisciplinary projects in other parts of Scotland. Key standout examples are the Paisley Corridor Improvement and Forth Bridge Refurbishment projects.
Paisley Corridor Improvement
The Paisley Corridor Improvement (PCI) in Renfrewshire is a £169.8 million project to upgrade one of the busiest two-track railways in Scotland to three and four tracks. As part of this, Balfour Beatty Rail is midway through a £27 million multidisciplinary contract on behalf of Network Rail to construct additional running lines and install associated overhead line equipment (OLE).
At first sight, the project looks quite straightforward. 4.5 miles of a widely spaced two-track railway are being upgraded to three tracks with an additional 1.5 mile section of four tracks between Glasgow Central and Paisley Gilmour Street.
However, this six-mile stretch of railway handles more than 300 trains every day and forms a notorious bottleneck to services operating on the Ayrshire Coast and Inverclyde lines. There is no way it can be closed during the upgrading process.
The very nature of converting a busy two-track railway into three and four tracks inevitably requires a lot of construction access, and managing this whilst minimising disruption has been the biggest challenge for the project team, as Balfour Beatty Rail’s Project Director Doug Lee explains:
“As well as heavy traffic on the route, the scheme also demands the installation of 39 point ends within tight schedules, significant civil engineering and modification of the OLE.
“Because of access problems on this busy route, the project does not comprise of a simple linear progression of works. Instead, staged works feature heavily – 26 stages over a 12-month period. If we miss a stage or overrun on any one of them, it will seriously impact upon the later stages.”
Access for the construction activities is limited to short possessions and the importance of maximising their use is critical to meeting a demanding programme of works.
The frequency and nature of the possessions vary throughout the project to suit the traffic demands and many weekends have been planned for 11 plus 8 hours duration rather than the traditional straight 29 hours. In this way, the railway is restored to traffic for the busiest part of the day, from late morning until mid evening.
The most recent possession was for 72 hours over the weekend of 6 August 2011. 12,000 man hours were worked over that weekend, split between Balfour Beatty Rail, Network Rail and Invensys Rail. An extensive programme of electrification, signalling, track work and civil engineering formed part of the first major commissioning stage of the project as a whole.
The second part will take place over Christmas 2011 although there will be some significant interim track and electrification works during September involving four 54 hour possessions.
The project is on track to be delivered successfully and on time at the end of 2011 and is of strategic importance to Balfour Beatty Rail.
“We are very keen to maintain our business presence in Scotland and PCI forms a vital part of our business plan in this respect,” says Doug.
“This contract demonstrates the strength of our partnership with Network Rail north of the border and we look forward to delivering a first class service.”
Paisley Corridor improvements. Photo: the rail engineer.
Refurbishment of The Forth Bridge
Balfour Beatty Regional Civil Engineering is currently undertaking a works contract, in partnership with Network Rail, to refurbish the Forth Bridge.
The works on the Forth Bridge are carried out in a series of phased operations at a number of locations at any one time.
Complex access scaffold is erected and the work areas screened from the environment before the existing layers of paint, applied over the last 120 years, are removed using an abrasive blasting technique. Steelwork requiring maintenance is then repaired before the new paint is applied in three protective layers, to preserve the steelwork for years to come.
The Forth Bridge is a marvel of Victorian engineering, carrying the East Coast Main Line railway over the Forth Estuary by way of a 2.5km cantilever bridge.
Designed by Sir John Fowler and Sir Benjamin Baker and constructed by Sir William Arrol at a cost of £2.5 million, it incorporates 55,000 tonnes of steel held together with some eight million rivets.
This unique structure has been in constant operation since its opening in 1890 by the then Prince of Wales (later King Edward VII) and has been the subject of the legend “like painting the Forth Bridge,” a job that has never been completed.
The bridge in fact has only ever been painted in a single operation when it was built but has been continuously maintained ever since, with painting being carried out where and when it was required.
The contract is set to mark the end of the modern myth when the painting on the Forth Bridge comes to an end in 2012.
The painting on the Forth Bridge comes to an end in 2012. Photo: EIFION.
Recent successes
While Balfour Beatty can’t lay claim to be the first painters of the Forth Bridge over a century ago they can rightfully put their stamp on a number of high profile rail projects successfully delivered in Scotland over recent years.
Edinburgh Waverley Railway Station
Edinburgh Waverley railway station is immense. It covers an area of 25 acres in the centre of Edinburgh and is used by over 19.2 million passengers a year. It is Britain’s second largest station after London Waterloo.
The station was first opened in 1846 and was rebuilt between 1892 and 1902. In 2008 Network Rail delivered a £150 million project to improve the infrastructure of the station and provide much-needed extra capacity.
This included two new, longer platforms and the reintroduction of platform 5, extensive track remodelling and new signalling to allow four more trains to pass through the station per hour each way, and extra platform capacity for longer commuter services.
Improved appearance
The next stage was to improve the appearance of the station for passengers. In 2009 Balfour Beatty Regional Civil Engineering was awarded a £50 million 3-year contract to refurbish and completely re-glaze the 34,000m2 station roof with clear, strengthened glass to shed new light on the station concourse and platforms.
The project will see all of the old glazing on the roof replaced including a large section made of clear plastic sheeting, the result of a low cost temporary fix made twenty years ago.
The station’s original Victorian ironwork features are to be repaired and repainted while non-essential station furniture, buildings and redundant high level walkways will be removed. In addition, new lighting and roof drainage systems will be installed, footbridges renovated and the concourse and platforms will be resurfaced.
Crash deck
Work commenced with the installation of a ‘crash deck’ at the east end of the station. This is being moved east to west across the station as the roof works progress. For increased safety and environmental considerations, the crash deck and the working areas are encapsulated.
Safely above the crash deck, the project team is stripping away old glazing, abrasive grit blasting the steel work to strip off old layers of paint and installing a support system for the new glazing. This will be made up of 28,000 new glass panels, the first of which was put in place on 21 April 2011.
Throughout the work the station will remain operational. Close working relationships between Balfour Beatty and Network Rail’s station personnel were required from the outset to ensure there is minimal disruption to passengers, trains and third parties while delivering safely a quality restoration of this historic station.
The contract is on schedule to be completed by November 2013.
Airdrie-Bathgate
The Airdrie-Bathgate Railway Project was the longest new conventional passenger line to be built for over 100 years. As part of the £300 million scheme, funded by Transport Scotland and delivered by Network Rail, Balfour Beatty Rail was awarded a £55 million contract in May 2008.
This involved the double-tracking of the single line between Airdrie and Drumgelloch as well as laying two tracks between Drumgelloch and Bathgate. The entire route from Airdrie to Edinburgh’s Haymarket Station was electrified with a 25kV AC classic booster system including the provision of new traction power supply sites along the route.
The railway infrastructure work naturally fell into two distinct sections. The first was the operational railway between Haymarket and Bathgate. This used the existing Edinburgh-Glasgow lines from Haymarket to Newbridge Junction in West Lothian and then the recently double-tracked branch to Bathgate where it included a new light maintenance depot complex.
The second section covers the route from Bathgate to Airdrie which extensively comprised a new two-track electrified railway.
Airdrie-Bathgate - Winner of Best Project - large (projects valued over £20m) at the 2011 Network Rail Partnership Awards. Photo: the rail engineer.
Birdsmill Viaduct
One of the more challenging aspects of the contract was the construction of overhead line equipment on the historic Birdsmill Viaduct. Built in 1849 and now Grade B listed, the multi-span masonry structure is located to the west of Newbridge Junction, carrying the Bathgate branch over the River Almond.
Access for construction plant and equipment was limited and, to add to the complexities, the works had to be undertaken in the harsh winter months of early 2010.
To complete them safely and on time, a coordinated approach was necessary to dovetail functional engineering and construction requirements, coupled with strong working relationships between contractor Balfour Beatty Rail and client Network Rail.
Due to the limited access to the bridge from ground level, plant and materials were brought in by rail.
The first construction operation on the viaduct was to install the OLE mast mounting brackets. This involved removing some of its masonry to make way for a new cast-in-situ concrete plinth, installing the bracket mounting bolts, coring through the outer masonry to make provision for the tie bar, and then installing the brackets themselves.
As much of this was carried out on the river spans, the use of scaffolding would have been very difficult and costly. As a result, specialist subcontractors undertook the work using a rope access system. Once the brackets were in place, the overhead line gantries could be easily installed.
New track
On 7 June 2010, Balfour Beatty Rail’s New Track Construction (NTC) machine started work. This high output system can lay new track at a rate of up to 250 yards per hour by implementing a continuous process of sleeper and rail installation onto a pre-prepared formation. The unit comprises a truss wagon, reception wagon, self-powered wagon and sleeper carrying wagons.
As well as high output production, other benefits are high quality track installation and lower manpower and plant requirements as well as reduced risk of injuries during track installation compared with traditional techniques. The NTC provides a means of constructing track that is consistent with both Network Rail’s ‘Safety 365’ and Balfour Beatty’s ‘Zero Harm’ policies.
Overhead line foundations, structures, cantilevers and return conductor wiring were the first elements of the new-build section to be installed. Carrying out this work before the track was laid provided flexibility in the type of plant and equipment that could be used.
When the trackbed had been prepared and rail positioned, the NTC unit came into operation. The final elements involved the overhead line wiring, tamping and stressing.
Power supply
A new traction power supply was provided via a 2x18MVA feeder station at Bathgate in which a Distribution Network Organisation compound has been installed that contains two 25kV disconnectors. Sectioning of the supply for the new-build railway is undertaken by track sectioning cabins located at Raiziehill and Drumgelloch.
This taxing project, made more complicated by the logistical problems of work spread across 40 miles of southern Scotland, was completed by Balfour Beatty over a two-year period without an over run.
Photo caption: Airdrie – Bathgate – Winner of Best project – large (projects valued over £20m) at the 2011 Network Partnership Awards
Glasgow Central Station
Glasgow Central Station is the largest of the two main line stations in Scotland’s second city, and is the second busiest station in the UK outside of London (Birmingham New Street is slightly busier). It was first opened in 1879 and, as passenger numbers grew, has been enlarged and rebuilt several times since.
With the recent resurgence in rail travel, and the improvements to the Paisley Corridor that runs out of Glasgow Central, it was time for another rebuild.
Balfour Beatty Regional Civil Engineering was contracted to do the work, including the removal of the existing platform 12 and the construction of two new 150m long platforms on the site of the short-stay car park.
Glasgow Central station caters for 34 million people per year. Photo: the rail engineer.
Big improvement
Work started on the new platforms at the end of September 2009 and full timetabled operations commenced on 24 May 2010. The Glasgow Central works are the biggest improvement to passenger facilities at the station since 1906 when the original 1879 station was increased from eight to 13 platforms.
Today the station caters for 34 million people per year and further growth is forecast. As a result, two new platforms have been constructed, each able to accommodate six-car trains.”
Glasgow Central Station is built on two levels and an extensive labyrinth of tunnels, vaults and arches exist beneath the site of the new platforms. This necessitated the installation of new structural columns and beams as well as the casting of a concrete slab to support the new platforms and associated track, S&C, OLE and signalling.
The reinforced concrete supporting columns with integral transverse beams were cast in situ, partly on new foundations with loads spread through existing foundations. A concrete slab was cast in situ on top of the columns; the slab track was then installed.
Platform 12
Work was carried out over Christmas 2009 to permanently close the existing Platform 12 (formerly 11A) and remove the track and overhead power lines. Platform 12 was never originally planned for passenger use. At the time of construction it was actually called the ‘fish, fruit and milk platform’ but it became increasingly used for passenger trains in recent years as the numbers and length of trains using the station increased.
However it was very unpopular with passengers because its location on the bridge over the Clyde was physically remote from the rest of the station and it was also out beyond the cover of the roof. The new platforms solve all of these problems.”
Miller’s arch
Closure of this platform permitted the track slewing and S&C work needed to create a route to the two new platforms, the entrance for trains being constructed through the station’s famous arch.
This impressive feature, built as part of the station’s 1906 extension, was designed by the Caledonian Railway Company’s architect, James Miller.
A collection of modern flat-roofed buildings had cluttered the base of the arch and these have been demolished to fully reveal the grandeur of the original Grade-A listed structure.
The arch was never designed to have trains passing through it so it’s fortunate that it offered sufficient clearance to accommodate two tracks and it certainly provides an impressive entrance into the station.
Now there is a clear unhindered view of the arch and, for the first time, this extends below its original visual base at platform level to reach the new tracks.
To maintain consistency with the overall arch appearance, the newly exposed sub platform section of arch has been stone clad as part of the project and replacement period doors have been provided in the arch abutments.”
Confusing?
The platform renumbering at Glasgow Central sounds somewhat confusing. Platform 11A, which had been temporarily renumbered as 12, has been replaced by the new Platform 12. The new Platform 13 did not previously exist.
The original Platform 12 has become Platform 14 and the old 13 is now 15. There should be no confusion however about the benefits delivered by the new platforms and station enhancements that Balfour Beatty has delivered.
Gourock Station
Gourock Station was always a bit of an afterthought. When the Caledonian Railway first built the Inverclyde Line, it terminated at Greenock Central. However, this was further from the quayside than the Glasgow & South Western Railway’s Greenock (Prince’s Pier) so the Caledonian was losing business. They therefore extended their line to Gourock Pier which opened in 1889.
The new station was right on the quay and was built to handle a large number of ferry passengers. It had three platforms, one on the quayside and two as an island platform, and extensive glass canopies over all three. However, in the 1980s these were cut back, and by 2006 the whole station was looking tired and dilapidated.
The station hotel had been demolished, as had the old pier, and all that was left were the three platforms, a closed station building, and a portable ticket office. Various improvement schemes for the area had been proposed, including moving the complete station, but nothing had been carried through.
So in 2010 Network Rail awarded a £4 million contract to Balfour Beatty Regional Civil Engineering to improve matters. A large part of the work was to improve the sea defences but in addition the platforms were to be renewed as were the canopies and OLE equipment.
The existing overhead wiring was fastened to the old canopies, so Balfour Beatty’s initial task was to remove that and erect conventional gantries. This left the site free for the removal of the canopies and installation of the replacements.
One platform face at a time has been taken out of service so that they can be resurfaced, and the whole project is on schedule for completion in November 2011.
In summing up to delegates at the open day, Peter Anderson commented:
“Today has been about launching our new office here in Shettleston, once again showing how committed we are to supporting Network Rail, Transport Scotland and local communities.
“We are here to make a difference and I would like to thank everyone involved.”
Light has been shed on four former railway tunnels in the Peak District National Park which have now be opened up to the general public as cycle trails.
The National Park Authority is improving the trail between Bakewell and Wye Dale by opening the tunnels for use by cyclists, walkers and horse riders, which have previously been closed for safety reasons.
The work is part of the £2.25m Pedal Peak District project, to encourage more people to cycle in the park.
As the project is located within the National Park, there have been constraints as much of the work was carried out in areas requiring Site of Special Scientific Interest (SSSI) consent from Natural England.
Contractor J Murphy & Sons Limited, working for the Peak District National Park Authority, has installed new cabling to light up the tunnels on the Monsal Trail which runs between Bakewell to three miles south of Buxton.
They were constructed as part of the Midland Railway line in the 1860s, which closed in 1968 as a result of the Beeching Report.
Murphy has also carried out six kilometres of surfacing to the trail and in Headstone, Cressbrook and Litton tunnels.
As this month sees the Signalling & Telecommunications issue of the rail engineer, it is opportune that Network Rail chose this month to announce the formation of Network Rail Telecoms.
Making the announcement, Peter Henderson, group asset management director, stated:
“Network Rail Telecoms has been created to design and deliver a new, single, unified telecoms organisation focussing, among other things, on improving the effectiveness of our deployment and use of telecoms assets and managing whole life telecoms in the most efficient manner.
“The team will be responsible for all of our telecoms assets, strategy and policy decisions, including operating, maintaining and enhancing our assets. They will also be responsible for the design and delivery of the service to the customer.”
To head up this new operation Andy Hudson has joined Network Rail as Telecoms Director.
He is currently vice president field operations and infrastructure engineering at Interoute Telecom, where he has helped transform the business from a fledgling operator to a successful European carrier. Andy takes up his new post in September.
Clive Kessell, writer for the rail engineer who headed up the Telecommunications Engineering department of BR and who was the Engineering Director at British Rail Telecoms before it was privatised, commented:
“It is good to see Network Rail recognising that telecommunications form an important part of railway operations by creating this new single department. The wheel seems to have gone full circle.”
The £70m improvement work on the North Cotswold rail line was completed on 22 August.
Parts of the line between Worcester and Oxford have been redoubled with a total of 21 miles of extra track having been laid.
Signalling and stations along the route have also been improved.
The final part of the project was a 16-day blockade in August when 15 miles of double track were aligned, tamped, stressed and welded between Moreton-in-Marsh and Evesham.
The first train ran through the new section at 6am and marks the culmination of a project that started in summer 2009 with double track laid in Chipping Camden Tunnel.
In a major article, this month’s issue of the rail engineer refers to plans to open up the space in front of Kings Cross station currently covered by the southern concourse.
As we went to press, Network Rail released their first plans for the new King’s Cross Square, work on which will commence after the Olympics towards the end of 2012. At more than 7000 square metres, it will be 50% bigger than Leicester Square and will reveal the stunning Grade I listed Victorian station façade for the first time in almost 150 years.
Architects Stanton Williams were chosen to work with Network Rail on the new square following an international design competition, attracting entries from more than 100 architects and urban designers from around the world. Network Rail says that “The square has been carefully designed to complement the area’s rich history and provide a modern, open space in the heart of London”.
Alan Stanton, director of Stanton Williams, said: “King’s Cross Square is a unique opportunity to create a new public space for London and a response to one of the most exciting urban challenges in the city. The scheme will become a focal point at the heart of the wider King’s Cross development bringing together major urban and transport improvements”.
You have probably all seen the new Network Rail poster “Next Stop: Year 2186”. The first time I saw it, I was on my way to meet Mike Palmer, Network Rail’s Project Manager, responsible for the current round of engineering work on the Royal Albert Bridge. The bridge features prominently on the new poster and Mike’s project sits comfortably with the poster’s message of “Getting the Great Western Main Line ready for the next 175 years”. The fascinating project outline in this article might not extend the life expectancy of the bridge very much but it will certainly make a significant contribution.
In 1952, the bridge was pronounced a Grade 1 listed structure by English Heritage. As a consequence, Mike’s project had to undergo considerable scrutiny before approval was finally granted and every effort has been taken to maintain the original Brunel features even though some no longer contribute to the structural integrity of the bridge. The £10m project involves replacing more than 50,000 bolts, carrying out significant steelwork repairs using 100 tonnes of new steelwork, the removal of up to 46 layers of paint and then covering the bare metal with a new protective system using 36,000 litres of special paint designed for harsh marine environments.
Public consultation
However, before the engineering work could start, the local community had to be involved since the bridge not only straddles the River Tamar, the boundary between Devon and Cornwall, it also spans over part of the town of Saltash on the Cornish embankment. There are many homes and other buildings that sit below and around the structure and these residents are understandably, very proud of what they consider to be “their” bridge. It has formed part of their landscape for many years making a very positive contribution to their community. However, over the years and now centuries, there have been a few concerns about noise and lead pollution whenever major engineering is taking place.
To ensure that the community was fully engaged in the project two meetings were held, each one attracting more than 100 local residents. Many of the residents had previously worked on the bridge and some came with trophies and exhibits of the bridge removed by previous generations of engineers. School children were shown how the bridge worked. Metal hangers and tubes were used to mimic the bridge and the children had to guess how many bricks the structure could hold. Plenty of advice was given and this feedback heavily influenced how the work was to be staged.
Knowledge of the structure
The design work has been carried out by global consultancy company AECOM. It recently took over Faber Maunsell and has inherited its considerable knowledge of the structure represented by one of its lead designers, George Lawlor, who has carried out detailed examinations and assessments of the bridge over recent years. Taziker Industrial Ltd won the contract in what Mike described as a very competitive contest with highly innovative submissions from a number of companies. Taziker Industrial (TI) is the principal contractor on site and will be carrying out all the scaffolding, surface preparation, steelwork repairs and painting themselves using only its internal staff. TI recently carried out similar work to Weston Mill Viaduct which is situated in Plymouth, about a mile away, carrying the railway over the entrance to Devonport docks.
The project has just started and it is expected to take two years to complete. The site compound and offices are now in place on the Plymouth embankment at track level for ease of access. At present, only the approach scaffolding is in place alongside two satellite compounds situated one on each bank. All the work will take place on the two central bow arched spans. This contract does not include any ongoing work to the approach spans. The work will be carried out in five stages to ensure that the additional loading imposed on the bridge structure resulting from the scaffolding and equipment will be within acceptable loading tolerances.
HAKI scaffolding system
TI is using the HAKI scaffolding system which is not only lightweight but has unique features built into the design. The scaffold which will include a pitched roof to avoid rainwater gathering, will be encapsulated to create a contained working environment. This will reduce noise levels and ensure that polluted matter will not escape. Within this scaffold tunnel, there will be an additional tunnel around the track to allow trains to run through the work area.
On the Tamar, even on a sunny still day the airflow through the bridge structure can be considerable and very variable which means that, in very high winds, the encapsulating membrane round the scaffold can act like a sail and impose significant additional loading onto the structure. To combat this concern the HAKI system is designed so that each encapsulating membrane is retained within a vertical channel on either side. This enables it to be retracted like a “roller blind” in the event of high winds reaching a pre-determined level. The retraction can be carried out quickly and safely to minimise wind loading on the structure from the additional surface area.
The aim is to ensure that only one fifth of each span is covered at any one time. Two short sections of scaffold will be erected and encapsulated at each end of each span, making four sections. The two sections on each span will then be moved toward each other in stages as the work progresses and they will finally meet in the centre of each span to form the fifth phase.
Painting system
Once each worksite is sealed, the removal of the numerous layers of paint can commence. Up to 46 layers of paint and corrosion will be grit blasted back to bare metal. This will expose the true extent of any corrosion damage and enable engineers to determine the precise remedial action necessary. It will also provide the painters with a clean surface to apply the three coat protective system, supplied by Leighs Paints which comprises a zinc primer, a glass flake epoxy intermediate coat and an impact resistant polyurethane finish coat. These will be sprayed on to the structure with hand painting in difficult areas.
The paint is expected to provide a 25-year protection to the structure which will be quite an achievement in this exposed, corrosive environment. Previous systems have only been effective for about seven years so this should offer a significant saving on future maintenance costs. The final colour selected is goose grey. The original colour of the bridge was an off white and was subsequently painted in various shades of browns, white and red until in 1911 it was painted grey and has remained that colour ever since.
Wherever possible, the grit blasting will be confined to daylight hours to minimise disturbance to the local community. Inevitably, there will be some noise when they work at track level and night time possessions are in place.
The intention is to clean the work area after each shift to remove all the grit, old lead-based paint flakes and other debris. To do this TI is installing industrial vacuum units. These units will be placed adjacent to the bridge so that the debris can be sucked out of the encapsulated working area with heavy particles going directly into vacuum skips and airborne particles into separate filtered skips ready for removal off site.
Steelwork repairs
Although the bridge is considered to be in a generally good condition, a major part of the work is to carry out steelwork repairs, especially to those parts that cannot normally be reached. One key area is where the vertical hangers supporting the track deck are attached to the arched tubes at the top of the structure. The main bolts to these hanger connections are known to be corroded and the diagonal bracings are not working effectively. Whilst repairs are being carried out to one hanger connection, the adjacent connection and the two on the opposite side of the tube will be strengthened with additional bolts until the repair has been completed. This sequence will be repeated for all the hanger joints until all have been repaired.
Brunel innovation
It is interesting to note that the corroded main bolt for each joint will become redundant when the repair is complete. However, each bolt is being retained to ensure that Brunel’s original engineering thoughts, intentions and actions are retained. Another example of this commitment to heritage is at track deck level where Brunel introduced diagonal cross girders. This system enabled Brunel to use a more slender section because the axle loads would always bear on more than one girder at a time thus reducing the load on each element. These diagonal girders became redundant in the early 20th Century when new cross girders were introduced at right angles to the track, but all one hundred and seventy six will be repaired under this current programme of work.
So everything is ready. The local community will be looking on with interest. Local charities and museums are to be offered fragments of the bridge to auction or exhibit and some of the bridge metalwork no longer required will be donated to local artists and sculptures to use as they see fit. This is a thoughtful way of engaging local residents. After all, The Royal Albert Bridge is part of their community; they will be hoping that their grandchildren will be able to view this magnificent structure in 2186, as well as the trains that will hopefully still be travelling across this significant county boundary, just as they have for the last 150 years.
