Cross-border rail projects don’t often feature in the British Isles, but now two are on the cards as the European Union is investing £17.16 million (€21.45 million) through the INTERREG IVA Programme.
A major upgrade of the Belfast to Dublin ‘Enterprise’ service has been allocated £12.2 million. Involving a significant overhaul of the train’s mechanical systems, new interiors, new livery, replacement of the Passenger Information System and a completely new electronic passenger reservation system and CCTV system; the project is expected to contribute to delivering increased passenger numbers.
Meanwhile, over €6 million has also been awarded to a major refurbishment of the Drogheda Viaduct. Originally built in 1885, the viaduct supports the main Dublin-Belfast railway line and is in need of urgent investment to ensure its long-term efficient operation.
These include steel repairs and full re-painting, renewal of track work over the viaduct, waterproofing of the deck, and installation of a new drainage system.
Match-funding for the projects has been supplied by the Department for Regional Development (DRD) in Northern Ireland and the Department of Transport, Tourism and Sport (DTTAS) in Ireland. Translink will act as lead partner for the Enterprise project with Iarnród Éireann (Irish Rail) leading on the Drogheda Viaduct refurbishment.
The GNGE project, described in The Rail Engineer recently (issue 116, June 2014), is moving on apace. During a recent 16-day blockade, fifteen level crossings and fifteen miles of signaling were upgraded with the latest technology – the most delivered so far in a single block of work.
The list includes some splendid names. Crossings were improved at Blotoft (Old Forty Foot Drain), Golden High Hedges, Water Drove (Gubbole’s Drove), Blue Gowt and Cherry Holt, amongst others.
These works were part of the now-completed Phase Four of the project. Phase Two – between Gainsborough and Doncaster (the phase numbering is geographic and not time-related) has also just been completed while Phase Five (Spalding to Peterborough) will take place in late October.
Speaking of the £280 million upgrade project, Phil Verster, route managing director for Network Rail, said: “The GNGE line is an important route for both freight and passenger trains. Demand for rail services continues to grow, and the upgrade of this line is an important project to help meet that demand.”
The new Dubai Al Sufouh Tramway will open on 11 November. Sheikh Mohammed bin Rashid Al Maktoum, UAE Vice President and ruler of Dubai, confirmed the official launch date following a test run on the first section of the new network.
Dubai’s tram system will be the first in the modern era to run exclusively catenary-free. The 14.6-kilometre network utilises Alstom’s APS II system (Alimentation par le Sol), an updated version of the one which was first used on Bordeaux’s tram in 2003.
A third rail is buried centrally between the two running rails, exposing only the top surface at ground level. This rail is divided into short insulated sections and only those actually under the tram at any one time are energised. Thus, pedestrians and pets can safely walk on exposed sections of the track without fear of electrocution.
Up until now, the system has been used on relatively short stretches of track to run through areas where unsightly overhead wires would not be welcome. Thus, the Bordeaux system has a total of 12km of APS out of a total network length of 43.3km.
However, Dubai is the first network to run without wires at all. Services on the 14.5 kilometre route will be run using Alstom Citadis 402 trams, each 44 metres long and with a capacity of 408 passengers. Interestingly, all of the stations will be fitted with platform screen doors, another first for a tram system.
Although Ethernet has been used for a number of years in Local Area Networks (LAN) for Information Technology (IT), it is now being used within railway telecoms applications such as customer information systems and Voice Over Internet Protocol (VoIP) and, more recently, within signalling control systems.
One recent example is the newly commissioned modular signalling scheme between Crewe and Shrewsbury, where Ethernet is used to connect together the; interlocking, trackside equipment, level crossing controllers and the control system. It is also now the dominant technology for Layer 2 of telecoms Internet Protocol (IP) networks.
Origin of Ethernet
The origins of Ethernet began in the 1970s with a requirement to link together computers on desks with devices such as printers.
The purpose of a LAN is to connect many more than just two systems. Connecting several thousands of computers to a LAN can in theory be done using a star, a ring, or a bus topology.
A star is every computer is connected to some central point. A bus consists of a single, long cable that computers connect to along its run. With a ring, a cable runs from the first computer to the second, from there to the third and so on until all participating systems are connected, and then the last is connected to the first, completing the ring.
Ethernet was invented at Xerox’s Palo Alto Research Centre (PARC) in the mid-1970s. Xerox was building the world’s first laser printer and wanted all of the PARC’s computers to connect with the printer. Bob Metcalfe and colleagues were asked to build a networking system to do the job.
Bob based his network system on ALOHAnet which was a radio network set up in the 1960s between several Hawaiian Islands. With this system, all the remote transmitters used the same frequency and nodes transmitted whenever they liked. Obviously, two of them might transmit at the same time, interfering with each other so both transmissions were lost. To overcome this problem, the central location acknowledged a message if it was received correctly. If it was not acknowledged then the transmitter sent the same packet again a short random time period later. The retransmissions made sure that the data got across eventually. It is ironic that Ethernet was based on a wireless technology as, 40 years later, wireless Ethernet systems are now widely used.
The Xerox team improved on ALOHAnet in several ways. First of all, Ethernet nodes checked to see if the ether is idle (Carrier Sense) and waited if they sensed a signal. Second, once transmitting over the shared medium (Multiple Access), Ethernet nodes checked for interference by comparing the signal on the wire to the signal they were trying to send. If the two didn’t match, there must be a collision (Collision Detect). In that case, the transmission was broken off. Both sides now knew that their transmission failed, so they started retransmission attempts using an exponential back-off procedure. The protocol was therefore known as CSMA/CD.
Photo: shutterstock.com.Ethernet can be compared to an audio telephone conference without a chairperson. If two people on the conference start talking at the same time they will normally pause, before one of them starts talking (transmitting), while the other listens (receives). Once the first speaker stops talking the second speaker starts to talk.
The experimental Ethernet ran at 2.94Mbit/s. In 1973, radio or wireless could not provide the speed required so Ethernet used a thick coaxial cable which was referred to as “the ether”. The name did not come from the anaesthetic ether, but from the luminiferous ether that was at one point thought to be the medium through which electromagnetic waves propagate. On 22 May 1973, Bob circulated a memo titled ‘Alto Ethernet’ which contained a rough schematic of how it would work.
So what of the competition?
Token Bus was introduced by General Motors for it its Manufacturing Automation Protocol (MAP) standardisation scheme. A token was passed around a ‘virtual ring’ on a coaxial cable and only network nodes that possessed a token were able to transmit. It was standardised by IEEE 802.4, and was mainly used for industrial applications. However, due to difficulties handling device failures and adding new stations to a network, token bus gained a reputation for being unreliable and difficult to upgrade.
Token Ring was introduced by IBM and was standardised as IEEE 802.5. A three-byte frame called a token travelled around a ring of cable connecting the computer nodes together. Empty information frames were also continuously circulated on the ring – when a device had a message to send it seized the token. The device would then be able to send the frame.
In the 1980s there was a battle between Ethernet and Token Ring as to which was the best LAN architecture and, at the time, a classic interview question was to describe the difference between the two. There were claims that Token Ring was superior to Ethernet. However, with the development of switched and faster variants of Ethernet, Token Ring architectures lagged behind Ethernet and the higher sales of Ethernet allowed economies of scale which drove down prices further. Eventually Ethernet won the battle as 100Mbit/s and 10Gbit/s switched Ethernet dominated the market.
So Ethernet won the battle for standardisation, by being cheaper, ultimately faster and, most importantly, by being an open standard. It developed over the decades and assimilated higher bitrate protocols until it has become ubiquitous, not just for LANs but nowadays within Layer 2 telecoms networks which can be used for both railway telecoms and signalling applications.
Ethernet becomes ‘The Standard’
Bob Metcalfe left Xerox in the late 70s and joined Digital. He was asked to develop another LAN system, but he considered that he had already developed the best there was with Ethernet. He suggested that Xerox and Digital work together on a standard, and subsequently a consortium with Digital, Intel and Xerox was formed, known as the DIX consortium. They created an open and multi-vendor 10Mbit/s Ethernet specification and published this as DIX Ethernet 2.0 in 1979.
Bob Metcalfe
The Institute of Electrical and Electronics Engineers (IEEE) were then involved in the standard and eventually produced 802.3, which is now considered the official Ethernet standard. There were some minor differences in terminology and format, but essentially it is the same standard. The IEEE originally avoided the word ‘Ethernet’ so that it would not be accused of endorsing any particular vendor. However, Xerox released all ownership of the name in due course so, while it appears to be a product name, Ethernet is now both an open technology standard and a name.
The first Ethernet was known as 10Base5 and used thick coaxial cable. The 9.5mm thick coaxial cable also wasn’t the easiest type of cabling to work with and subsequently a thinner solution was introduced in 1986 (10Base2) and called ‘Thinax’. This was much easier to install and use. The cables were half the size of ‘Thick Ethernet’ and looked similar to a TV antenna cable. Instead of cumbersome connectors, the thinner cables ended in BNC connectors and devices were attached through T-connectors.In 1991, a new specification was developed to allow Ethernet to run over unshielded twisted pair cabling (UTP) and known as 10BaseT. This is still universally used today.
UTP cables for Ethernet come as four pairs of thin twisted cables. The cables can be solid copper or made of thin strands. The former has better electrical properties; the latter is easier to work with. UTP cables are fitted with the now-common RJ45 plastic snap-in connectors.A fibre version was also introduced and known as 10BaseF (with 10 being the speed in Mbits/s).Every UTP cable is also its own Ethernet segment. So in order to build a LAN with more than two computers, it was necessary to use a multiport repeater, also known as a hub. The hub or repeater simply repeats an incoming signal on all ports and also sends a jam signal to all ports if there was a collision. The end result was a fast and flexible system, so fast it’s still in use today.
Bridges and Switches
The next step was simply to bridge between all ports. The multiport bridges were called switching hubs or Ethernet switches. With a switch, if the computer on port 1 is sending to the computer on port 3, and the computer on port 2 is sending to port 4, there are no collisions, the packets are only sent to the port that leads to the packet’s destination address. Switches learn which address is reachable over which port simply by observing the source addresses in frames flowing through the switch.
In 1998 the next iteration of Ethernet was introduced called Gigabit Ethernet. 1000BASE-T.
The new technology was introduced with only switch architecture and CSMA/CD was unnecessary as the two sides can both transmit at the same time. This is called full duplex operation, as opposed to half duplex for traditional CSMA/CD operation.
10 Gigabit Ethernet
A common way to create a LAN in a building or office was to have a series of relatively small switches, perhaps one per wiring closet where all the UTP cables come together. The small switches are then connected to a bigger and/or faster switch that functions as the backbone of the LAN. With users on multiple floors and servers concentrated in a server room, there’s often a lot of bandwidth required between the switches. So, even though computers with a 10 Gigabit Ethernet connection were not common, 10GE was badly needed as a backbone technology and the standard was published in 2002.
In 2006 10GBASE-T standard was published, allowing 10 Gigabit Ethernet over twisted pair cable. 10GBASE-T needed even better cables than 1000BASE-T and Category 6 cabling was introduced to reach 100 meters, with thicker insulation than previous versions.
Reaching for 100 Gigabit Ethernet, and beyond
After 10 Gigabit Ethernet, 100Gbit/s was the next obvious step. However, transmitting at 100Gbit/s and faster over fibre has numerous challenges, as the laser pulses that carry information through fibre become so short that they have a hard time maintaining their shape. The IEEE therefore kept open the option to make a smaller step towards 100Gbit/s with a 40Gbit/s version and, on 17 June 2010, published standards for both 40 Gbit/s and 100 Gbit/s Ethernet. Products are now commercially available.Nothing stops still with Ethernet though and so, in May 2013, 40 years after Bob Metcalfe’s memo to Xerox, work started on project IEEE 802.3bs for 400Gbits/s. To put this into perspective, a single telephone voice channel requires 64kbits/s, so a 400Gbits/s Ethernet connection could carry the equivalent of 6.5 million telephone calls.
Ethernet’s future
It can be seen that Ethernet has managed to survive over 40 years in production, increasing its speed by no less than four orders of magnitude. In those 40 years, all aspects of Ethernet have been changed and only the packet format has remained the same. It has evolved from simply connecting computers within buildings, to connecting whole campuses together, and is now to be found at the heart of nearly all modern telecoms networks. For example, Ethernet is now starting to be used within signalling control systems, both for vital and non-vital communications.The IEEE has several task forces and study groups looking at various improvements and variants and Ethernet will continually evolve, just as it has done over the last 40 years.The only reason Ethernet growth has slowed relatively over the past decade is because wireless LANs (in the form of Wi-Fi) have been introduced and are so convenient. However, wired and wireless LANs are largely complementary so, even though more and more devices go through life with an unoccupied Ethernet port, Ethernet is always there to deliver the speed, reliability and security that shared wireless can struggle to provide.
Terabit Ethernet
1000Gbit/s? On the one hand, this seems unlikely, as transporting 100Gbit/s over fibre is already a big challenge. On the other hand, in 1975 few people would have guessed that today we would carry around affordable lap tops with 10Gbit/s ports.
Gigabit Ethernet already uses parallelism by using all four wire pairs in a UTP cable, and many 40Gbit/s and 100Gbit/s Ethernet variants over fibre also use parallel datastreams, each using a slightly different wavelength of laser light. Telecoms carrier networks already transport multi-terabit aggregate bandwidths over a single fibre using dense wavelength division multiplexing (DWDM), so this seems an obvious opportunity for Ethernet to once again take existing telecoms technology, streamline it, and aggressively push the price down.
Bob Metcalfe’s view
Bob Metcalfe is now a Professor of Innovation at the University of Texas. He has predicted that the future of Ethernet will be:
Up – Ethernet data speeds will continue to increase, as can be seen by the release of 40 and 100Gbit/s, and now investigation work on 400Gbit/s.
Through – Ethernet will continue to be used throughout telecoms carrier networks to supplement and replace SDH (Synchronous Digital Hierarchy).
Over – It’s ironic that Ethernet was developed on a wireless technology before being a wired technology, but it will continue to be used more and more over the wireless ‘ether’.
Down – Ethernet will be used more and more down the technology hierarchy chain. That’s from network PCs to within sub-personal devices and micro-controllers, and into the embedded internet of everything. For example, there is already a lot of work specifying Ethernet for use within the automotive industry, and such uses will be for all industries and which must include railways.
Across – Both LAN and WAN (wide area network) speeds are relatively high, but very often constrained by the telecoms network connection. Ethernet will play a key role as Next Generation Telecoms Networks bridge the gap between LANs and Carrier Networks.
Ethernet is one of the success stories of the last 40 years and will be around for many years to come as it continues to evolve.
The exciting plans for signalling the Thameslink railway, including the introduction of the European Train Control System (ETCS) and Automatic Train Operation (ATO), were described in issue 109 (November 2013).
However, introducing impressive new technology to run a 24 train-per-hour (tph) service through the Thameslink core could be frustrated by the very object the systems are ultimately provided for – the human passenger.
During a recent visit to the project offices, Paul Bates, Network Rail’s Thameslink programme director, high capacity infrastructure, was keen to explain that his portfolio included optimisation of the station infrastructure to facilitate swift movement of passengers off and onto trains, minimising train dwell times. This work is underpinned by extensive human factors research assessments and workshops which are being progressed within Paul’s internal team.
Level access is coming to Thameslink
In addition to the heavy commuter and leisure flows of passengers, 117 million per year, the Thameslink route serves the airports at Gatwick and Luton as well as the major hub of St Pancras International. Thus, travellers lugging huge suitcases around the Thameslink network could be a serious impediment to the efficient and rapid train dispatch necessary to meet the 24tph throughput of trains. And then there are wheelchairs and pushchairs to consider.
Train companies usually require advance notice of travel in order to provide assistance in dealing with Persons of Reduced Mobility (PRM). A wheelchair requires a member of the TOC staff to be in attendance on the platform at the right time to deploy a Mobile Boarding Ramp (MBR). Project manager Keith Jones reckons this process adds three minutes to dwell time, creating a negative impact on a service interval of two and a half minutes.
In view of the performance risk of using the MBRs, the project team are hopeful that the provision of new fixed ‘HUMPs’ will obviate their use, though this will be a decision for the train company. Thameslink platforms at stations in the core – London Bridge (Platforms 4 and 5), Blackfriars, City Thameslink, Farringdon and St Pancras International will be fitted with the PLA-HUMP®. This is an innovative pre-fabricated modular raised platform system which allows level access to the train for travellers with limited mobility, wheelchair users, families with pushchairs and those carrying heavy suitcases, by eliminating the vertical gap from train to platform.
Photo: shutterstock.com
Handy HUMPs
Pipex px®, a company based in Plymouth, will supply the fibre reinforced polymer modular units. Studs are installed and the prefabricated units brought from the factory and plugged in on site. They will be delivered with markings already moulded in as specified, such as the yellow platform ‘stand back’ stripe and the disabled sign. The HUMPs are approximately 25 metres long and are designed so that they extend to both the PRM carriage doors.
The advantages of the Pipex px® HUMP include corrosion resistance, light weight, long life 60+ years, low electrical conductivity, and virtually maintenance free. Individual panels may be replaced if damaged or worn. As you would expect, the units comply with the Fire Precautions (Sub-Surface Railway Stations) Regulations, known as the ‘Section 12’ Regulations which were introduced in the aftermath of the tragic fire at King’s Cross Underground station in 1987 in which 31 people were killed.
The specific HUMP design for the platforms at Thameslink core stations will be compatible with the floor level of the forthcoming Class 700 stock. As the trains currently in service on the route have different floor profiles to the Class 700 vehicles, the ramps will not be installed until the introduction of the Class 700 is complete and exclusive.
An unplanned bonus for wheelchair users is that they are saved the indignity of being ‘assisted’ by a member of station staff as they will be able to take the lifts and ‘drive’ the wheelchair straight onto the train under their own steam, thereby restoring self-esteem.
Detailed study
The manufacturer is currently working with Exeter University to determine if there are any implications relating to the different slip resistances of the HUMP, yellow marked area and existing platforms. Exeter has done some ground breaking research on the morphological features of floor surfaces and effects on slip resistance property. There is a Network Rail standard for this but the proximity of Underground platforms nearby may add a further consideration. Detailed design work for the HUMPs is currently in progress.
Clear signage will ensure that those needing to use the level access are directed to wait in the right place on the platform. Every train must stop with the PRM carriage (large space for wheelchair and luggage) adjacent to the ramp.
Trains will be formed of eight or twelve carriages and the stopping position will be such that the centre of the train will always coincide with the centre of the platform. The PRM carriage will be in the centre of the train, so that if a train set gets reversed, say during a Sunday engineering diversion, it makes no difference. Trains run under Automatic Train Operation (ATO) or manual driving and it is reckoned that an overshoot of 2.5 metres will still line up the PRM carriage doors with the ramp.
Further significant high-frequency work is being undertaken by ergonomist Kate Moncrieff in conjunction with studies by the University College London. UCL runs a project for the empirical evaluation of door-open times for high-demand rail systems using their fully equipped Pedestrian Accessibility Movement Environment Laboratory (PAMELA) facility. This work is to demonstrate that the dwell times could be met.
Photo: shutterstock.com
Mind the gap
A significant consideration for the Thameslink project team is PTI. This relatively new acronym in the railway industry stands for platform-train interface and refers to the gaps both in terms of width and height between a station platform and a train, but also includes risks relating to electrocution and falls from platforms without trains being present.
Ian Prosser, director of railway safety at the Office of Rail Regulation, wrote in issue 107 (September 2013): “An area where there’s been a lot of focus from ourselves and the industry is PTI where serious injuries and fatalities occur. Some of it is down to passenger behaviour issues, but much is quite predictable. So to manage the risks it is important to have a good understanding of your location particularly with how people move around stations. Whenever work is done at a station, it’s important that the work actually takes this into account.”
ORR’s ‘Health and safety report 2013-14’ states that there were four passenger fatalities in 2013-14. All occurred at the PTI and involved passengers falling from the platform edge on to the track.
Keith Jones explained that the project intends to equip Thameslink station platforms with gap fillers, where required. There are two types of gaps the project team are looking at, vertical and horizontal between platform edge and train floor at the location of the PRM doors. The Hump will go some way to addressing the vertical gap. To address the horizontal gap, the team are currently reviewing mechanical and passive gap filler solutions. Gaps vary in size.
Generally, passive black rubber gap fillers will be permanently fitted to the platform edge such that trains will not make contact with the rubber but the gap has been effectively closed. There is a company in Cornwall who are currently assisting the project team.
Due to platform curvature at Farringdon, for example, gaps here are larger and necessitate a creative solution. It is here where a mechanical gap filler is proposed. It will integrate with the HUMP to ensure a seamless method of boarding for PRMs and is currently under development with a company who have them installed and commissioned for Parisian subways RATP and RER.
The associated control system uses a combination of laser and hyper frequency distance indicators and speed radars to automatically deploy and retract the filler by detecting the arrival of a train in the correct dwell position and subsequent departure. The system complies with the SIL3 safety level and SIL2 for reliability. Progression is currently at project GRIP 3 stage (development). Assuming all engineering and human factors are satisfactorily addressed, they are due to be installed by 2018.
Customer Information Systems (CIS) and way finding
Due to concerns over the readability of the current TFT screens in variable lighting conditions, the team is evaluating the performance of TFT screens versus an LED alternative.
The principle is to ensure people are on the right platform, at the right time, and standing in the right position. Any hesitancy on the part of passengers soon causes back up, leading to bottleneck and protracted dwell time. The project team’s theory, validated by UCL, goes like this:
“As an intending passenger I arrive at Blackfriars station forecourt wishing to travel to Gatwick. On the route maps and CIS indicators in the foyer I determine that my train leaves from platform one and the destination is Brighton. Following the signs, I take the escalator to platform level. A big ‘1’ positively registers in my mind that I am on the right platform. As I turn to walk along the platform, I immediately see a CIS screen in front of me confirming the train I have seen downstairs is indeed the Brighton train calling at Gatwick. As I look up from that confidence factor, I see more screens further along the platform. Hence I’m certain that I’m on the right platform, I see my train listed and if I walk further along I’ll still get information.”
There will be six screens back- to-back along the length of the platform. The idea is to spread out passengers along the platform for a 12-car train.
A further innovation will be the provision of hatching on the platforms to help ‘condition’ commuters to stand in optimal positions for the train. Research by UCL indicates that this should provide some benefit.
Consideration was given to giving Thameslink routes an identifier, for example, Bedford – Brighton could be the ‘alpha line’, as a means for passengers to identify the service required. However, the significant and changeable permutation of train origins, destinations, calling points and routing, made this concept far too complex. So, as part of the way finding process, stations will display diagrammatic route maps similar to those used on Underground stations.
This will enable passengers to quickly determine the likely train destination that will serve their own alighting point. Signage in general will be consistently applied at Thameslink stations from London Bridge to St Pancras International.
Reliable displays
Passengers need to have confidence in the accuracy of information displayed by the CIS screens. The display “07:15 ON TIME” still displayed at 07:20 doesn’t look good.
Hitherto train information displays have relied upon outputs from the signal box train describer system, a rather limited raw source of data. Enter project DARWIN which was described in issue 84 (September 2011).
Promoted 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 success of the new CIS displays will thus lie in the ability of DARWIN to predict the future to a high degree of accuracy. DARWIN will know exactly where the 07:15 is. DARWIN will cover perturbation but the train company will have local control in the event of major issues.
At the time of writing, unit size, font size, displayed content, sequencing and type of technology (LED/TFT) is being evaluated by trials in conjunction with supplier Infotec of Ashby de la Zouch. Zoning, such as First Class, is being considered and departure indicators will show the number of carriages as boxes on the screen lined up with the zones.
On the computer demonstration it was intriguing to see that each box contained a different level of infill. Keith Jones explained that the Class 700 has the capability to report back the loading of each carriage. This might be useful to help passengers position themselves adjacent to the doors of the least-full carriages.
Unfortunately there is a problem with using this concept on Thameslink. During the peaks, trains are likely to arrive in the core from the country already full and the system cannot predict how many passengers are likely to alight at any one station. So this facility will not be taken forward at present. There is, however, a plan for the TOC to gather the data and use this in the future.
The platform CIS displays will be in pairs. The left hand unit will show train in platform or about to come in, with destination, time and stopping points, whilst the right hand unit shows the next train to come. The all-new CIS screens are going up in 2016, way finding and signage in 2018. Laser scanning has been deployed to evaluate the visibility of existing signage and facilitate development of new signage as part of the plan to create a much more user-friendly passenger environment.
Train driving and dispatch
This article has focussed on the work undertaken by the infrastructure owner to manage dwell times efficiently. Needless to say, the train operating company has been heavily involved with the various factors of train driving and dispatch to ensure 24tph is delivered through the core. Crucial to this objective will be a highly-disciplined approach to the dispatch of trains.
The new Thameslink, Southern & Great Northern franchise management contract commences on 14 September and will be known as Govia Thameslink Railway (GTR). Franchise incentives are linked to delivery of the Thameslink Programme, reflecting Govia’s role in collaborating with Network Rail.
Thanks go to Network Rail’s Paul Bates, Thameslink programme director – high capacity infrastructure; project manager Keith Jones; Kate Moncrieff, ergonomist and human factors specialist; and Paul Bull, designated project engineer, for their help in preparing this article.
Near Newcraighall, five miles south east of Edinburgh Waverley, is a siding with a folding buffer stop.
It is this siding that is to be extended by 49 kilometres to form the new Borders Railway, the longest new UK domestic railway for over a hundred years. The line will open in autumn 2015. Principal contractor for this project is BAM Nuttall with Siemens sub-contracted for signalling and telecoms.
The project was described in detail in issue 110 (December 2013) but, with all of the work starting to come together, it was time to make another visit. Project director Huw Wark was, as always, only too pleased to show the progress that his 800-strong team has made. With a budget of around £15 million a month, there’s a lot going on.
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Track laying set to start
The main phase of track laying is to commence in October when frequent engineering trains will pass through this buffer stop. These trains will not require possessions as special instructions have been written to transfer the trains from Network Rail infrastructure to the project.
Bottom ballast for the track will have to be supplied by road – about 5,000 lorry loads will be required. Ballast stockpiles are already being created at access points. Track laying is to be done by a team from BAM Rail in Holland using the technique employed on the HSL-Zuid, the Dutch high speed line. This is expected to lay track at the rate of approximately 1.2 kilometre a day and complete track laying by the end of the year.
Ballast is already in place at the top end of the line. Further down, structures are substantially complete but some earthworks remain, especially at the southern end of the project.
Beyond the buffer stop
The area between the folding buffer stop and the city by-pass is to be transformed by the new railway. Here, Shawfair station has been built on the site of Monktonhall, a large modern colliery which closed in 1998. Not surprisingly, this section of the line required mining remediation and, as recently as August, revealed a hidden mineshaft. With the track solum now complete, the mine should give the project no more surprises.
For planning reasons, the railway is in shallow cuttings in this area with surplus soil generated as a result. This has not been wasted as it is being used for landscaping in the area, requiring frequent lorry trips, many of which are off road using disused railways.
Structures Challenges
The largest structure on the line is the Hardengreen viaduct. Here, a road improvement scheme cut away the original railway embankment and replaced it with a roundabout. The approaches to the viaduct use the reinforced earth system of precast concrete facing panels tied together with galvanized steel reinforcing straps held in place by the backfill. This system, supplied by Reinforced Earth Company (RECo), is used on some of the other project structures and is a good solution where there is a restricted footprint, as at Hardengreen. It does not, however, provide the foundation for a derailment retention parapet such as that provided on the actual viaduct. For this reason the track over the approaches will have guard rails.
Fifteen kilometres south of Hardengreen is the line’s summit at Falahill. Here, getting the railway under the A7 requires another significant structure. Constraints at this location included a national grid pipeline, local cottages, a rocky outcrop and the A7. Satisfying the requirements of various stakeholders at this location proved difficult and resulted in two changes to the original parliamentary plan.
The solution adopted is a long, highly- skewed bridge. Currently, the 200 metre long, slightly curved concrete box that will carry the single-track railway under the road stands alone, with earthworks to carry the A7 over the bridge under way. Much of the adjacent rock was removed by blasting to provide useful material for construction. The resultant hole is now being filled with surplus unsuitable spoil.
Hardengreen ViaductThe line has two tunnels, Bowshank and Torwoodlee, respectively 39 and 43 km from the start of the new line. Bowshank tunnel has double track as it is part of a four kilometre dynamic loop. With the requirement for passive provision for electrification, tunnel clearances are tight. For this reason, the floor of the 200-metre tunnel has been lowered and Rheda 2000 slab track installed. When visiting in early August, it was seen that the Down Loop track had been installed after two weeks work and that work had just started on the Up Loop.
The tunnel rails, supplied by Tata Steel, have Railcote® for corrosion protection.
End of the Line
The town of Galashiels is in a narrow river valley and was expanded around the original railway which took up much space in the town. After its closure in 1969, almost all of the railway land was built on. As a result there is now just enough space to get the railway through the town with some deviation from the original route and bridges to raise the railway over new roads. These bridges are now complete although most of the associated earthworks have yet to be completed.
Just beyond Galashiels, the original line was in a deep cutting that had since been filled in. This cutting, where a considerable number of utilities all converged, has now been excavated except where a BT fibre optics cable crosses the line which is now supported by a scaffold bridge. This enables the infill below it to be removed and, if necessary, the track to be placed underneath, before the cable is diverted through a new bridge at the end of the cutting.
After this cutting, the line crosses the River Tweed on the five-arch Redbridge Viaduct. The new single-line railway shares this viaduct with a footpath which is part of the Southern Upland Way.
Beyond is the end of the line, Tweedbank station. This is intended to be a railhead for Borders towns to the south and so will have a 240-space car park. A relatively late project design change, announced by Scottish Transport Minister Keith Brown in November 2012, was the requirement for it to have 220 metre long platforms to accommodate charter trains. There are, however, no run round facilities so any such train will have to be ‘top and tailed’.
Tweedbank may be the end of the line but, when The Rail Engineer visited, ballast had been laid ready for its switch and crossing which was to be installed on 16 August.
Bowshank tunnel.Also to be seen at Tweedbank during this visit was the cable plough. This ploughs a small- diameter, multi-way tubular fibre duct into the ground along the route. Fibre cables are then blown through these ducts. There will be no troughing along the railway. Instead there is this buried cable and signalling islands at each set of points, each with a relocatable equipment building fed from the nearest power supply.As far as telecoms is concerned, the Border Railway requires 15 radio masts along its 49 kilometres. This indicates the nature of its terrain as the new 22km Airdrie-Bathgate line only required two.
Slow start, rapid progress
For various reasons, it has taken a long time to get the Borders Railway project started. It took ten years from the Bill being first presented to the Scottish Parliament in 2003 to the start of main works last year, although some advanced works were undertaken from 2010. Those along the line could therefore be forgiven for thinking that the project was not going to happen.But there has been rapid progress since last year and, within a few months, construction trains will be seen on the line. Civils works have been prioritised to clear the northern end of the line for track laying and, with all earthworks expected to be complete before winter, this should reduce any potential delays from bad weather.
Although, as with all projects, some uncertainties remain, the Borders Railway is well on track for project completion in summer 2015.
Farringdon Station will be “the heart of the heart” of Crossrail. It is going to be the only station in London with interchanges between Crossrail, London Underground services and the Thameslink network. Writes Chris Parker
It will also be the only station in the city to have direct connections to three of London’s five airports, Heathrow, Gatwick and Luton. There will be up to 140 trains per hour through the station by the time the Crossrail services are in full swing, and it is forecast that these will carry up to 150,000 passengers/day.
With this in mind, The Rail Engineer was very pleased to be invited to go and see how the works are progressing. The day included some unusual sights such as Farringdon Thameslink Station from below track level and a grade 2 listed brick arch viaduct suspended some distance in the air! But more of those later…
Bored not excavated
Jose Garcia, construction director, described how, in addition to this station contract, the BFK JV (BAM Ferrovial Kier) has been responsible for all of the running tunnels west of Farringdon, right through to the east end of the new station. In total, on these and other Crossrail contracts, the JV and its suppliers are employing some 2,000 people and training 100 apprentices (almost one third of the total number of apprentices on the entire Crossrail project).
Looking at Farringdon itself in more detail, Jose said that it will have the longest platforms on Crossrail, some 400 metres in length, stretching between two ticket hall complexes at the east and west ends of the station. Developments above each ticket hall will be constructed, creating commercial and retail space.
Farringdon is unique among Crossrail stations in that the platform tunnels are being constructed in a different manner from the others. Whereas the others are being excavated as underground caverns, constructed from shafts driven down from above, at this site the running tunnels are being used as pilot tunnels.
The difference was driven (sorry for the pun!) by programme issues. At other station sites it suited the programme to begin to excavate the station caverns before the running tunnel TBMs arrived, allowing them to break into the voids already created. Where they needed to continue beyond, they were then hauled through the station area to continue their drive on the other side.
At Farringdon this order of construction would have been too disruptive. Instead, it was decided to allow the tunnel boring machines (TBMs) Phyllis and Ada to complete their drives from the western portal through to the east end of the station at Farringdon before work on the station platform tunnels commenced. There was another advantage in this sequence of work, in that this methodology reduces the likelihood and magnitude of settlement affecting the buildings and structures up above. Given the close proximity and sensitivity of infrastructure like the London Underground’s Barbican station and the Network Rail Farringdon station, this was no bad thing!
Opening out the station
The eastern end of the station was the end of the line for Phyllis and Ada and so they were diverted to the side and buried. Once they were clear, the excavations could begin, to create ten-metre diameter tunnels from the seven-metre diameter running tunnels over the required length of each to accommodate the platforms.
The platform tunnels are being lined with fibre- reinforced sprayed concrete (FRC), so the work involves careful removal of the precast segmental tunnel lining that was installed by the TBMs, the excavation of the ground behind to the required profile, and finally the robotic spraying of the FRC lining to the enlarged tunnel bore (pictured). Clearly, this is a sensitive business and so it is carried out in carefully managed stages. Normally these are threefold, first the crown, then the benches either side and finally the invert at the bottom. This ensures the minimisation of ground movements and the consequent settlements of structures above.
Despite the care taken in planning and executing the works, some settlement was still to be expected, and so mitigation measures were provided, in the form of compensation grouting. This technique can be applied after settlement has occurred to restore the ground to its original level. Alternatively, it is feasible in some circumstances to raise a structure slightly in advance, so that the works below cause it to settle back to where it came from.
Which method is used depends upon the nature of the structures and the type and magnitude of the expected movements. Some structures, for example, can tolerate heave better than settlement and those would probably be best treated by lifting ahead of settlement. For others the converse may apply.
The compensation grouting is being applied using “tube a manchettes” that have been installed from five 14 to 15 metre deep grout shafts so as to cover the whole area above the tunnels. Some 18,000 linear metres of grout tubing have been installed and the area covered is about 27,000 square metres in extent. One of the grout shafts lies in the adjacent corner of Charterhouse Square, and it was during its construction that several intact ancient skeletons were discovered.
One further benefit of the pilot tunnel technique is the reduction it means in the quantity of spoil to be taken out of the site by road. Since the spoil from the seven-metre running tunnel bores was taken away through the tunnel by conveyor back to the west portal, then something approaching half the spoil went away from the station tunnels without needing to be trucked away from the site. 90,000 wagon loads of spoil were therefore removed from London’s congested roads.
Halls at each end
Jose was assisted by his colleague Tom Moore in describing the construction of the two ticket hall complexes. These lie at the east and west extremities of the platforms. The differences between the construction methods employed at these two sites illustrates once again the care that has been taken to select the most appropriate engineering solution at each and every location on the Crossrail project.
The western ticket hall structure is being constructed from the bottom, eight levels below ground, upwards. Segmental piled walls surround the shaft, forming its sides as the spoil is dug out from between them. As the construction proceeds temporary props are required to ensure that deflections of the piles are restrained appropriately.
When the right level is reached for a floor, this is shuttered and cast with ties into the wall piles. Once the concrete in the floor slab has reached the required strength, the floor is able to act as the prop to the wall piles, and the temporary props can be removed from that level. At the time of the visit the props had just been removed from level -6, two floors up from the base of the works.
Top down at the other end
At the East ticket hall, Tom and his colleagues are involved in top down construction works for a trapezoidal shaft going down to 42 metres below ground. A slab was built two storeys below ground level, once again inside an area walled by segmental concrete piles that extend down below the intended bottom floor level. This first slab provides the permanent propping to the piled walls at that level. There are both permanent and temporary apertures in it, the former for escalators, lift shafts and so on, the latter for use during construction. Temporary steel props above the slab provide restraint to the pile walls pending later construction of floor slabs at level -1 and at ground level.
Five plunge columns have been driven within the shaft to foundation depth below the level of the bottom floor. These will act as internal columns to support the permanent floors, several of them are also serving as supports to a partial temporary slab at ground level which is being used by construction plant and vehicles. Once the station works have been completed, the plunge shafts will form a significant part of the foundations for the steel framed over-site development which will sit above the ticket hall.
Excavation within this shaft was initially by means of a clamshell grab on an excavator sited on the temporary ground floor slab. This worked through the apertures in the slab to raise the spoil and deposit it into tipper trucks for removal from site. With this form of construction, the floor slabs are constructed on the excavated base of the hole once the correct level is reached. Each slab then provides the requisite propping to the wall piles at that level, permitting the excavation to continue beneath the slab to the level for the next floor down. This repetitious process has now passed the point where, at -30 metres, the excavator could no longer reach from ground level. Having peaked at a productivity of seventy-eight 20tonne tippers full of spoil in one day, the machine handed over to a mobile crane and skip for the rest of the job.
New techniques
The crane/skip operation is the first in the UK to use “hook-cam” technology to permit the safe operation of the system down through the apertures in the floor slabs to the working level far below. Cameras on the hook, connected wirelessly to screens in front of the crane driver, permit the driver to direct the skip on the crane hook safely to where it is needed, and bring it safely back to ground level when full. Slinger/Signallers are still employed at the working level, in radio contact with the driver, but the camera technology ensures that they need not stand below the hook to guide the driver during the lowering or raising operations.
On completion of the excavations, when the floor slabs are all cast in place, work will commence to fill in the temporary apertures in the slabs and to construct the sloping structures upon which the station escalators will sit. Screwed starter couplers have been connected into the reinforcement of the slabs to permit the necessary connections between the slab steel and the reinforcement in these further structures.
The segmental piled walls of the shaft are being lined with reinforced concrete as the floor slabs are completed, to hide the rough piled faces.
Five plunge columns have been driven within the shaft to foundation depth below the level of the bottom floor. These will act as internal columns to support the permanent floors, several of them are also serving as supports to a partial temporary slab at ground level which is being used by construction plant and vehicles. Once the station works have been completed, the plunge shafts will form a significant part of the foundations for the steel framed over-site development which will sit above the ticket hall.
Another interesting feature of the works is the interface with the Network Rail Thameslink line and the Farringdon Thameslink station. The East shaft lies on the line of a pair of sidings that run through Farringdon Thameslink into Moorgate. These have had to be severed to allow the Crossrail scheme to be executed. At present, this gives some interesting views of the Thameslink station from points not normally available. The severed tracks are to be reinstated upon completion of the Crossrail station.
Assorted oddities
At the opposite side of the worksite from the station lies Lindsay Street Viaduct, a Grade 2 listed structure built many years ago to carry the eponymous street over the Network Rail lines. Unfortunately some of its foundations lie over the site of an escalator shaft for the new Crossrail station. In consequence it has been necessary to underpin several of the piers of the bridge and make provision for them to be lifted with hydraulic jacks should any settlement occur during the construction of the shaft. The bridge now appears, at first sight, to be hovering slightly above ground!
As mentioned, one of the grout pipes runs below Charterhouse Square, which lies across the road from the station. The Charterhouse began as (and takes its name from) a Carthusian monastery, founded in 1371
and dissolved in 1537. It was known to have been on the site of one of the large graveyards from the Black Death plague. One skeleton had been found previously elsewhere in the Square about one metre below ground. However, the discovery of several neatly stacked intact skeletons, all aligned east/west about two to three metres below ground as the grout shaft was under construction was a bit of a surprise. Crossrail had been prepared for some findings, but not quite this.
The site at the time of the plague lay well outside the City of London in rural surroundings. Staff from The Museum of London and local volunteers from the community have been investigating two pits within the Square, hoping to find remnants of the monastery and to discover the reason for a linear geophysical anomaly that crosses the square. They are rather hampered by restrictions on where they may dig, caused by the requirement to pay due respect to the ancient and protected plane trees in the square. However, they are persevering – assisted by the Crossrail and BFK teams who are very proud of their close collaboration with the Museum and of their very good relations with the communities in the area more generally.
These good relationships were exemplified for us later during a tour of The Charterhouse itself. Here, it was explained how the project has been liaising with the Brothers and other local communities to ensure that there is minimal harm done to local interests whilst the Crossrail project passes through the area. The Charterhouse is worth a visit – it is open to the public at certain times, though there is a small entry fee payable.
So, with Ada and Phyllis buried for good, and several ancient skeletons uncovered, a lot has been going on at Farringdon. And there is a lot more still to do.
Many thanks to Mabel Garcia Aranda, BFK JV corporate responsibility co-ordinator; Jose Garcia, BFK JV construction director; Tom Moore, agent for the JV for the Farringdon East Ticket Hall; Nisrine Chartouny, Crossrail project manager for the C435 Farringdon Station contract; Jay Carver, Crossrail’s lead archaeologist; Nick J Elsden, project manager of the Museum of London and Brother Philip of The Charterhouse for their help in preparing this article.
The Stockholm Citybanan (City Line) is a new commuter railway tunnel currently under construction beneath central Stockholm, which will be used for the Swedish capital’s commuter rail service.
The line will be six kilometres long, double track and electrified, and will run between Tomteboda and Stockholm South (Stockholms södra) station.
Also included in this project, which is valued at approximately £625 million, are two new stations: Stockholm City Station which will be located directly below T-Centralen, the central station of the Stockholm Metro, and Stockholm Odenplan Station which will be located below the Odenplan Metro Station. This new commuter line is scheduled to enter into service in 2017.
The current position in Stockholm is that all the railway traffic – commuter trains, regional trains, long-distance services and freight – all share the same two tracks. As there are four tracks either side of this congested area, this restricted length of track is often referred to locally as the ‘wasp’s waist’. There has been very little change to this layout since the existing two track railway was first introduced in 1871.
At the turn of the century, the delays and congestion caused by the wasp’s waist reached such a level that something had to be done. It is not dissimilar to the many similar problems that we have in the UK addressing congestion problems of a track configuration designed for the eighteenth century – London Bridge, Reading and Manchester Victoria to name a few. However, in any large city, the solution is never easy or cheap and it always demands ingenuity of the highest order. The Stockholm Citybanan is no exception.
Photo: MIKAEL ULLÉN
Doubling track capacity
When the project is completed, all commuter trains will have their own dedicated tracks and the other existing rail services will continue to operate on the present two tracks. This means that track capacity will be doubled, and trains will be able to run more frequently and punctually. The interchanges for passengers will also be much smoother because the new stations will be located close to bus routes and metro lines.
Initial proposals to solve this problem were first considered by Swedish Railways back in 1988, but detailed planning and design of the project did not start until 2000 after which construction was underway by 2009. There are eight major civil engineering contracts that have been let, some are design and build and others build only.
The six kilometre long tunnel path will consist of blasted tunnel lengths leading up to 300 metres of tunnel that has been partially constructed on dry land then floated out and submerged into its final position – but more about that later.
Tunnel blasting
At the time of writing, two contracts for blasting the tunnel paths either side of the Malaran Lake, where the submerged tunnel is being constructed, have been completed. This work has been carried out by contractors Strabag for the Norrmalm tunnel and Zublin for the Södermalm tunnel. Each contract is valued at approximately £35 million.
Photo: AHLQVIST & ALMQVIST
The bedrock in Stockholm consists mostly of granite and gneiss, which is ideal for blasting and more than 4.5 million tonnes of rock has been removed. The extracted rock is the property of the contractors who have transported it to different crushing facilities around the city ready for recycling. However, the significant volume of rubble only amounts to 15% of that required for the many different infrastructure projects currently underway in the Stockholm region.
Immersed concrete tunnel in Riddarfjarden
Blasting a tunnel under the canal section of the Malaren Lake was not an option since the bedrock between Riddarfjarden and Söder Mälarstrand lies too deep underwater. Various alternatives were considered but it was decided to build an immersed tunnel that would rest on piling under the water. The 300 metre long tunnel was constructed in three sections, each one being about 100 metres long, 20 metres wide and 10 metres high. Each section weighed about 20,000 tonnes.
For the first stage of construction, large steel boxes that would form the outer skin of the soffit and sides of the tunnel were fabricated at a shipyard in Tallinn, Estonia. These were then successfully towed across the Baltic and into Lake Mälaren, a distance of 235 miles. Before reaching their destination, each box successfully negotiated a lock system at Södertälje where the clearances were very tight with only millimetres to spare.
Whilst in an industrial harbour close to the final resting place, each of the three steel boxes was used as formwork for an inner layer of concrete, 1.1 metres thick, forming the sides, top and base of the tunnel. The steel boxes are being retained to provide an outer shell that will serve as a watertight membrane throughout the life of the structure.
Photo: MIKAEL ULLÉN
During the summer of 2013, the tunnel sections were submerged. The southern section went first then the northern and finally the central section. Each section was lowered onto bored piles which were formed in four groups of 72 bored concrete piles, each 400mm diameter and constructed in layers of sediment varying between 15 and 25 metres before keying into the granite strata below. This pile structure acts as an underwater bridge to ensure that any subsidence of the seabed would not affect the stability of the tunnel.
The southern section was immersed at the land end into a watertight pit that had been constructed close to the shore and under an existing roadway that was diverted using a pontoon to allow a connection point to be constructed. Seventeen metres below water level, this links into the main tunnel and allowed the roadway section to be repositioned.
The jointhouse
The northern section was connected to ‘the jointhouse’ – a concrete structure 9.5 metres long, 25 metres wide and 12.5 metres high – constructed in a deep pit where the rock tunnel emerges at the river bank. Two rubber gaskets, each measuring 19.8 metres, were used to seal the joint and allow the tunnel some degree of movement when the water temperature fluctuates. To make the fitting of the final segment easier, the northern section was pushed into the jointhouse by one metre and, after the central section was in position, it was drawn back again, into its final resting place.
Temporary ballast tanks placed inside each section were filled with water and, using the principles of Archimedes, the sections were sunk to a level just above the pile caps so that the barges could make final adjustments and ensure that each section fitted to the adjacent unit as designed. Once the sections were in their final position, additional water pumped into the water tanks enabling them to rest on hydraulic bearings and bearing pads in their final position.
PHOTO: 3XN
Once the ends of each section were removed and the joints made water tight, additional concrete was added to the soffit providing additional weight and allowing the ballast tanks to be removed. In addition, rock ballast was placed onto the top of the submerged tunnel ensuring that the weight of the submerged tunnel exceeded the water displaced as required by the above mentioned principles. The completed structures had to accommodate a constant gradient change which meant that one end of the structure is now fifteen metres below water level whilst the other end is only five.
A separate service and emergency exit tunnel has been constructed running parallel with the track all along the six kilometres of tunnels.
New stations
Two new City Line stations now need to be built. NCC is the contractor for the Stockholm City station which will be used by more than 114,000 passengers each day. The station is located directly beneath T-Centralen Metro Station and replaces Stockholm Central as the station for commuter train services. The work, valued at £155 million, includes associated tunnel work as well as the construction of two platforms with escalators providing direct access to all metro lines.
The second station is Stockholm Odenplan which replaces Karlberg Station and will be designed to accommodate 90,000 passengers per day. The contractor is Bilfinger and the value of the work is £129 million which includes tunnelling work as well as the construction of the station itself. This station will become an important interchange and it will reduce travel time considerably for those passengers who need to change between commuter trains and buses or the metro.
Photo: HANS EKESTANG
New railway viaduct
To accommodate the revised track layout, a new £26 million railway viaduct is being built between Arsta bridges and Alvsjo. The contractor for this work is Zublin which started work in 2011 and is using a moving scaffold system to construct the 1.4km-long single-track structure.
They say that eight out of every ten rail journeys in Sweden begin or end in Stockholm. When the City Line is finished, there will be room for twice the number of trains on the tracks through the city. This means that it will also be possible to improve rail connections with the Mälaren Valley and the whole of Sweden.
Carrying out such an undertaking, in such an environment, makes it essential that all the work is carried out in a safe and professional manner. This ensures minimum disruption to road and rail traffic and the continued stability of adjacent buildings while giving close consideration to ground water levels and, not least, maintaining the welfare of the hundreds of thousands of residents and neighbours. To overcome some of the particular challenges of this new line, ingenious ideas had to be considered and, certainly, the submerged tunnel fits into that category.
The slim-waisted wasp is starting to show a far more generous waistline. That will be good news for the 80% of Swedish railway passengers who are set to benefit from this project.
Biodiversity is the variety of all life on Earth. It includes all species of animals and plants – everything that is alive on our planet, and human survival depends upon it. Writes Tertius Beneke
The UK National Ecosystem Assessment (NEA), which was published in June 2011, demonstrates just how much nature provides for us in the UK. Caroline Spelman, Secretary of State for Environment, Food and Rural Affairs, lists many examples in Biodiversity 2020: A strategy for England’s wildlife and ecosystem services. These include “the enormous value of inland wetlands to water quality, the value of pollination to agriculture, the health benefits of experiencing nature and, not least, how nature and wildlife enrich all our lives”.
The ground breaking UK NEA is a comprehensive account of how the natural world, including its biodiversity, provides us with services that are critical to our wellbeing and economic prosperity. However, the NEA also shows that nature is consistently undervalued in decision-making and that many of the services we receive from nature are in decline. The most recent analysis shows that over 40% of priority habitats and 30% of priority species are in decline.
This is a call to arms for everyone to halt this decline – for the benefit of our and future generations. In Network Rail Infrastructure Projects (IP) we are taking some bold steps to address this challenge, seek solutions and identify a way forward to not only halt biodiversity loss, but to ensure we deliver genuine, long-term benefits for biodiversity as part of what we do.
Major landowner
Network Rail is the fourth largest landowner in Great Britain. It not only owns 22,000 miles of track but also over 30,000 hectares (74,000 acres) of land. This connects and passes through some very unique habitats, such as Sites of Special Scientific Interest, Areas of Outstanding Natural Beauty and many other statutory and locally designated nature reserves. Network Rail itself owns hundreds of protected sites which it manages in order to protect and enhance their unique attributes, whilst also balancing the need to manage an operational railway infrastructure.
In addition to sites designated for nature conservation, the extensive rail corridor provides a home to a significant number of plant and animal species. Many of these are protected by legislation and all offer a rich contribution to the biodiversity of the UK.
There are also several dedicated pieces of legislation, relevant to Network Rail, that enforce the protection of specific species and their wider habitats. For example the Natural Environment and Rural Communities Act 2006 (NERC2006) places a requirement on statutory undertakers like Network Rail to “protect and where possible enhance biodiversity.”
The wider picture
Over the last few decades, UK biodiversity has been in steady decline. Different methods and mitigation measures have been used to protect and enhance biodiversity as a part of development, but these have had varying degrees of success and a new focus is needed.
The introduction of the Department for Environment Food and Rural Affairs (DEFRA) biodiversity metric gives developers an effective tool to quantify biodiversity in units. This Government issued metric is a first for the UK and allows this all-too-often poorly understood topic to be discussed much more readily within an industry context. It also enables us to set biodiversity targets such as No Net Loss or Net Positive and the ability to track progress against achieving these targets much more accurately and robustly than ever before.
At Network Rail, we are using the metric to quantify the impact that essential maintenance, renewal and infrastructure projects may have on existing habitats or species as well as quantify how much biodiversity our enhancements are creating in order to determine whether our efforts to halt biodiversity loss and deliver benefits are working.
In IP, we have taken the bold step to include a biodiversity target in our business plan that covers the next five-year Control Period “to make a measurable net positive contribution to biodiversity in the UK”. The target combines the use of the DEFRA metric to calculate biodiversity and thus measure our progress towards Net Positive as well as linking in the wider UK biodiversity agenda recognising the positive role and contribution Network Rail can have in this area.
Business performance
For all the legal and moral motivators that are driving our Net Positive biodiversity agenda, it would be remiss not to mention the business benefits of enhanced biodiversity and proper habitat management.
Network Rail has developed a company standard, NR/L2/TRK/5201 Management of Lineside Vegetation. Through the creation of a structure of lineside vegetation that allows the safe operation of the railway, this allows a diversity of habitats ranging from open spaces, important for insects and pollinators, through to scrub and trees.
The implementation of this standard brings with it the opportunity to retain a diverse lineside habitat whilst, at the same time, creating or improving habitats that may be in decline. Any such work will be done sympathetically and, wherever possible, with the involvement of the local communities which live alongside the railway.
The use of the DEFRA metric will enable the existing habitat to be classified and its condition assessed. The implementation of the lineside standard, in combination with our biodiversity Net Positive target, will help to improve the resilience of the network during the changing seasons and associated storm events but with a lineside that has an improved biodiversity.
DEFRA Biodiversity calculations
In 2011 DEFRA published a technical paper proposing a metric to calculate biodiversity and transform the uniqueness, condition and amount of habitat into a comparable unit measure.
DEFRA developed this metric to inform biodiversity offsetting schemes as part of its national pilot test on offsetting. However, we in IP are not using the metric during the final stages of a project when the unavoidable loss of biodiversity requires compensation. Instead we are using the metric during the early design stages to improve our efforts to avoid impacts on biodiversity and our design of biodiversity enhancements by evaluating how many biodiversity units we will be able to enhance during the lifetime of a project.
For us it is very clear that offsetting for IP is an absolute last resort and, even then, only when we can demonstrate that the loss of biodiversity is unavoidable. There has been a great deal of controversy over recent months regarding offsetting. At Network Rail, we fully appreciate and agree with concerns surrounding offsetting and recognise that it is important for companies to understand their approach to biodiversity and be able to justify how decisions are made and on what basis, and above all strive to achieve a Net Positive.
As a standard operating procedure, IP will be applying the Biodiversity Hierarchy which strictly enforces the process that many options are first considered and implemented before offsetting becomes available for consideration. We operate within a constrained railway environment with restrictions and limitations on tree and habitat planting and recognise that, in certain situations, offsetting has a role to play in achieving a Net Positive for biodiversity. Whenever it does so, our aim is that our efforts result in local community benefits from enhanced biodiversity.
The Biodiversity Hierarchy
The Biodiversity Hierarchy is a hierarchy of decisions or options that will be applied during the management of biodiversity for IP. Our goal is to avoid impacts on biodiversity and ultimately enhance biodiversity. The further down the pyramid, the least preferred the options are from a biodiversity and IP perspective.
(The Biodiversity Hierarchy)
Enhance – As part of the project the biodiversity in the affected area will be enhanced to achieve a measureable Net Positive;
Avoidance – Harm to wildlife species and habitats will be avoided where possible, for example through locating on an alternative site with less harmful impacts;
Mitigation – Where harm cannot be wholly or partially avoided, it will be minimised by design or by the use of effective mitigation measures that can be secured by, for example, conditions or planning obligations;
Compensation – Where, despite whatever mitigation would be effective, there would still be unavoidable loss, as a last resort, this will be properly compensated for by measures to provide for a Net Positive for biodiversity.
In IP, one of our major programmes, the Thameslink Project (TLP), has already implemented the Biodiversity Hierarchy and achieved the ambitious target of “Net Positive” for biodiversity. A £6.5bn enhancement programme of one of Europe’s busiest commuter routes, TLP has led the way by delivering Network Rail’s first net positive biodiversity offset scheme. Using the metric the TLP calculated its ‘biodiversity units’ and applied the hierarchy to review measures to retain as much habitat and replant the railway corridor where possible, with offsetting as a last resort.
Collaborating with the London Wildlife Trust and Lambeth Council, TLP has created new woodland and enhanced existing woodland at Streatham Common, a nature reserve in South London. The offset achieves a net positive for TLP, enhances the reserve for wildlife and adds to the enjoyment of Streatham Common by local communities.
TLP’s biodiversity offset is being undertaken because of the drive to be a sustainable programme and has sought to establish good practice in a very new field. As such it is named by DEFRA as a UK demonstration project in recognition of how, with careful planning, offsetting can enable development to continue and deliver benefits for biodiversity.
“We follow the mitigation hierarchy and are continually improving our biodiversity work to deliver positive outcomes for both the natural environment and people,” explained Amelia Woodley, Thameslink Environment Manager.
The challenge for IP is to take this good practice forward and embed it in the rest of our projects. The goal is to not only apply this to our major programmes, such as the Network Rail Crossrail Programme which will be one of the first to take this forward, but to implement this on all of our projects. In principle, wherever a project has an impact on biodiversity or where the opportunity arises to create and or enhance biodiversity, this method will be applied.
Our People
As with any initiative, it will not happen without our people and our supply chain working with us to achieve this. So far this objective has been received very positively and we have tremendous support from our staff. On TLP the programme has established transparent policies and procedures to support its staff and has partnered with its supply chain providing training on how to achieve Net Positive.
“Engagement with our staff and supply chain has been crucial to deliver a biodiversity benefit as a legacy to the communities in which we work,” said Shane McEntee, Carillion Environment Manager.
The real work now lies ahead in applying this approach consistently, giving our people the tools and training to deliver this effectively, working with our supply chain and learning from them, as well as learning from our own experiences, and ultimately having a refined and efficient process that delivers a net positive result for biodiversity.
Tertius Beneke is principal environmental specialist with Network Rail Infrastructure Projects
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