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Trenchless Technology Helps to Keep the UK Rail Industry Running
 Insituform Technologies® Ltd (ITL) is a name renowned worldwide for its work in the water industry and in particular the water and sewer pipeline renovation markets. What is not as well understood is that the company’s technologies and contracting skills are just as appropriate to projects in the rail industry.
Initially the link between railways and pipelines does not seem to be a usual match. But, a look at the evening news programmes in extreme weather conditions shows just how difficult rail transportation often is when the track drainage systems, river/stream culverts and other under-rail crossings fail to work effectively. In addition, installation of a new crossing can bring train speeds down to a crawl as works progress beneath operating rail lines.
This is where the range of trenchless technologies offered by ITL is playing an increasingly effective role within the rail sector.
Being a broad spectrum contractor, ITL can offer various state-of-the-art techniques which, when applied efficiently, can maintain rail services at an almost normal level, minimising disruption and delays not just to the trains themselves but more importantly to rail passengers.
 The types of works undertaken by ITL include:
- Survey and identification of culverts and recommendation of appropriate renovation solutions
- Design and engineering verification of required renovation solutions
- Relining and renovation of existing pipes, culverts and manholes including various lining options such as cured-in-place pipe (CIPP), segmental glass reinforced plastic (GRP) and ferro-cement systems and grout sealing
- Construction of new rail crossing pipelines by guided auger boring (microtunnelling)
- Construction of rail crossing service ducts using moling techniques
- Shaft construction
- Pipejacking
- Replacing old or damaged pipes with a new pipe of similar or larger size by using pipebursting techniques
Having worked in the rail industry for the past 25 years, ITL holds all currently required approvals and certifications to operate within the rail sector. The Company’s highly experienced rail-based workforce have the necessary knowledge and understanding of network rail specification and design criteria, including full Achilles Link Up accreditation as an approved supplier as well as PTS and COSS training and certification.
Typical of the range of associations within which ITL operates are:
• Specialist sub-contractor on the Channel Tunnel Rail Link contracts – for survey, design and rehabilitation of all existing culverts
• Sub-contractor for major shaft construction works on CTRL contract
• Specialist sub-contractor on West Coast Mainline
• Specialist sub-contractor to Nuttall/Network Rail Southern Zone Construction Partnership and Murphy Network Rail Alliance for rail culvert survey, design and rehabilitation
• Specialist sub-contractor to Birse Rail for contracts at Walsall, Kidderminster, Kirby –in-Ashfield and Stratford upon Avon
To date, ITL has achieved all of its rail projects for all clients on time and within budget.
TYPICAL PROJECTS
A project which describes some of the varied contracting activities available from ITL is the Grayswood Railway Culvert Project which included both the construction of a timber heading and the use of GRP lining works.
Client Network Rail, through its principal contractor Edmund Nuttall, engaged ITL to complete its refurbishment works on a severely deteriorated culvert running under a rail embankment in Grayswood, Surrey. The refurbishment was required because the culvert, which carries substantial  water through a heavily wooded area and under the large railway embankment, had suffered a partial collapse. The location meant that the only feasible option for the work was to utilise specialised trenchless technology techniques.
The structure comprises a 1,200 mm x 750 mm horseshoe shaped brick culvert running over a length of 167 m. From its entrance, the culvert runs at a steep gradient before levelling out and continuing towards its outfall. Over many years, the natural action of the fast running water hitting the base of the slope had caused considerable erosion to the invert of the culvert. This in turn led to a partial collapse and structural failure of the culvert as the side walls and the crown of the structure were effectively undermined with the loss of the invert. Inspection of the site showed that a substantial amount of work would be required to refurbish and maintain the culvert’s structural integrity for future use.
Due to the location of the affected section of culvert and the depth from ground level at 11 m at the point of collapse, any refurbishment works would be very difficult to undertake.
 After careful consideration of the options available, it was decided that the best solution would be to remove the damaged section of culvert and replace it with GRP pipe and structural grouting. The GRP pipe, in comparison to the existing brick culvert, would give excellent flow characteristics, dramatically reduce friction at the levelling out point at the base of the fall and substantially increase overall structural strength of the system.
The first technique to be used for the project was the installation of a traditional timber heading. After excavating the heading manually, the timber frame was constructed within the existing culvert, eliminating the need for extensive excavations from ground level.
The heading was designed to be sited over the structurally unsound length commencing and ending at points in the culvert length where the culvert was in its original shape and still structurally sound.
Work progressed by removing the damaged section of culvert and replacing it with a structurally designed timber frame. The design of the timber structure was capable of withstanding the surrounding ground pressure.
 Once the timber heading was complete, the GRP liner pipes were installed by positioning each segment in place and grouting the surrounding annulus to complete the structural lining. This formed a continuous pipeline through the timber heading. As part of the grouting process, the annulus behind the timber heading was also grouted to form a complete structural pipeline joining the two existing sound sections of brick culvert.
Commenting on the project for ITL, Project Manager Gwynne Rees said: “This was not an easy project for us. With access limited to using the existing culvert and the limited working space within it, logistical difficulties were our main problem. Getting materials in whilst getting spoil from the heading out needed to be handled very efficiently and carefully. Despite these difficulties we managed to give Network Rail a fully refurbished culvert within the expected timeframe and to budget.”
FINNIESTON TUNNEL
The Finnieston Tunnel built originally in 1896 is on the main electrified rail line between Helensburgh and Airdrie via Glasgow Queen Street Station. The line carries passengers and freight and serves Western Scotland to Fortwilliam and Mallaig. It is situated between Charing Cross and Patrick Stations in Glasgow. This line is exceptionally busy carrying commuters from Helensburgh, Dumbarton, Clydebank and West Glasgow. The typical frequency of trains is one every ten minutes.
ITL had been contracted by Scottish Water to carry out a full cleaning and profiling project over approximately 700 m of mainly large-diameter sewer which runs under the track. In addition, the works also included some 42 drop shafts connecting from the street level into the main sewer.
 The project is basically being completed in two phases: the cleaning phase and the renovation works. Once the cleaning programme was completed and all rehabilitation requirements were identified, the rehabilitation programme to carry out the works labelled the project as as moderate and high risk. The specific methodology to be utilised for the rehabilitation operations include: patch lining, GRP lining and conventional CIPP lining. The latter option may also include the use of the Insituform® iPlus™ Composite liner, which uses a carbon fibre and/or glass fibre reinforced liner for added strength. The addition of the carbon and/or glass fibres allows a reduction in liner thickness by nearly 50 percent compared with conventional liner materials which maximises flow capacity whilst still providing a strong liner solution.
Due to the requirements for track possession and isolation of the electrified line, the cleaning works were carried out on consecutive Saturday nights only, with normal operating hours being between 01.00 am and 05.00 am for each working shift. These limitations are specified by Network Rail to facilitate the works safely within the tunnel.
The initial cleaning programme commenced in November 2008. After completing 13 working shifts, approximately 74 tons of heavy debris and silt have been removed from the sewer.
Commenting on the works for ITL, Project Manager Robin McKay said: “This is not one of our easiest projects. The limitations on working hours, restrictions on track possession, limited access and the confined working conditions in an ageing sewer as well as the personnel safety support required means our short time on site over Saturday nights places a lot of pressure on our cleaning crews to achieve a lot. They are performing very well. Although we won’t understand the full renovation requirements until the cleaning aspect of the project is completed, we are already investigating the logistics of how the site restrictions will determine the methodologies we will need to utilise and what can be achieved in the time frames open to us.”
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