CHANNEL TUNNEL RAIL LINK - Phase 2
The above map shows the various contracts in CTRL Section 2. Click on the map or choose from the list below for more details.
Contract 342 - Highways Works Connecting A2 to Ebbsfleet StationHighways Works Connecting A2 to Ebbsfleet Station
The main contract consists of all highway works associated with Ebbsfleet Station and a link from the Thames Tunnel to CTRL Section1. Between the southern portal of the Thames tunnel at Swanscombe and the A2 at Southfleet in Kent, two bridge structures through existing chalk spines at Galley Hill Road and the North Kent Line are being built and a bridge over the River Ebbsfleet, a wide span pedestrian bridge, elevated embankments and structures to connect to the North Kent Line are being constructed and a cut and cover tunnel under the existing A2 at Pepper Hill. Utility diversions are being put in place, enabling works to take place for construction of Ebbsfleet Station and the approach roads from the A2.
ITM was contracted to install, and monitor for a five-year period, the following instrumentation:
Thames Tunnel
The 2.5km long twin bore tunnels (7.15m internal diameter) run from the northern portal in West Thurrock marshes to the southern portal at Swanscombe in Kent. A total of 1km cut & cover and open cut approach structures at both the north and south portals are also being built.
ITM was contracted to install instrumentation to monitor the performance
of the cut and cover tunnel structures, temporary and permanent props, groundwater
levels and ground pore water pressures both outside and under the tunnel
wall, along with settlement monitoring of new embankments. All tunnel instrumentation
was data logged.
Instrumentation installed included:
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West Thames: Ripple Lane to Thames
The main contractor is constructing an 11.4km length of the CTRL between the tunnels at Ripple Lane and the tunnel approach at Thurrock. Structural works include the 520m long Rainham Viaduct (across Rainham Creek to Ferry Lane), the 1km Aveley Viaduct (crossing the LT&S railway) and the 1.2km Thurrock Viaduct (passing over the Dartford Tunnel approaches and under the Queen Elizabeth II Bridge).
ITM were contracted to carry out extensive Site Investigation works using both standard and restricted access cable percussive, and window sampling drilling equipment, with in-situ testing and laboratory testing of samples, with boreholes drilled for the Rainham Creek crossing, the Rainham and Thurrock Viaduct pier bases, for the freightliner terminal exchange sidings, and various other structures, both existing and planned, along the route.
Instrumentation was also installed on both Rainham Creek and Lafarge
railway bridges to monitor tilt, around the pier bases at Thurrock Viaduct
to monitor settlement and lateral movement during the piling operations,
at Tank Hill Industrial Estate to monitor pore-water pressures, settlements
and lateral movements under new embankments for link roads, and at Rainham
for Load test embankments for the Exchange Sidings.
Instruments installed included the following:
Barrington Road to Ripple Lane
The main contract is the construction of 5.3km twin bore running tunnels (internal diameter 7.15m). There will be a 500m long cut & cover tunnel and retained cut approach at the Ripple portal together with emergency access and incident control facilities. A ventilation shaft is also being constructed at Wayside Road.
ITM were contracted to install the following instrumentation to monitor lateral movements within the cut & cover tunnel and vent shaft walls, and lateral and vertical movements within the sub-strata ahead of the tunnel at the Freightliner Terminal at Rainham:
CTRL Tunnels Stratford to Barrington Road
The main contract is the construction of 4.7km long twin bore running tunnels (internal diameter 7.15m). Ventilation shafts and headhouses are being constructed at both Barrington Road and Woodgrange Road.
ITM were contracted to install 6No strings of horizontal in-place inclinometer sensors, to measure the sub-surface settlement troughs above the two tunnel drives heading east out of the Stratford Box.
This involved the drilling of 6 No horizontal boreholes between 25m and 35m in length. The boreholes were to be drilled from within the constructed Stratford Box, from a purpose built platform constructed on the upper level at the east end of the box. The boreholes were diamond cored through the existing diaphragm wall, and then rotary cored at a down angle of between 3 and 4 degrees. Care had to be taken in the drilling of the boreholes to ensure that they remained, over their full length, in a straight line in plan, to follow exactly the intended line of the tunnel drive, and that their end point, which was to be within 2 metres of the Central Line tunnels ahead of them, was located precisely in both the vertical and horizontal planes. Borehole surveys were carried out during the drilling of the boreholes to ensure correct alignment, and on completion for final mapping of their exact locations in plan and section.
On completion of the boreholes, inclinometer casings were grouted in place, and once the grout had cured, strings of horizontal in-place inclinometer sensors were installed within the casings. These were wired to data loggers fitted with GSM telephone modems for automated monitoring and data download.
Total equipment installed comprised:
London Portal (Edge of Kings Cross Railway Lands) to Stratford Box
The main contract is the construction of 7.5km long twin bore running tunnels (internal diameter 7.15m) from Stratford to the London Portal, near St Pancras. Ventilation shafts are being constructed at Corsica Street and Graham Road, utility mitigation works at Caledonian Road and the construction of rail trackbed, walkways and drainage inside the tunnels
ITM have supplied a range of instrumentation to the JV. To monitor the performance of the Tunnel Boring Machine (TBM) against the strict settlement criteria and to justify the design assumptions, a series of extensometers was provided to provide detailed information on ground movements in the initial few hundred metres. Multipoint Rod Extensometers and Inclinometers were installed to depths in excess of 30m.
Construction of the Graham Road access shaft to more than 50m deep called for 70 strain gauges to monitor the loads in temporary props at 7 levels, while to monitor 64 cross passages required a further 8 Strain Gauges in each passage.
One of the major areas of concern, requiring the greatest care, is where the tunnels pass below Highbury and Islington Underground Station. As well as the importance of checking for any movement of the existing Victoria Line and Northern and City Line Tunnels, particular care must be taken to maintain the alignment of the two escalators. A comprehensive, near real-time monitoring system has been installed, requiring no less than 248 Electrolevels, 8 Tiltmeters and 10 Strain Gauges. Near real-time data will be available to the TBM operations room, the designers and LUL’s Engineers’ office.
Prior to passing under the station, the tunnel passes out of the Woolwich and Reading Beds into the London Clay, and a further set of 4 Multi-point and 7 Single-point Extensometers have been installed to revalidate the TBM performance in this new ground.
Equipment Installed:
Civil Engineering Works in Kings Cross Railway Lands
The main contract comprises of civil works, including earthworks, bridges
and viaducts for permanent rail links for Midland Main Line (MML) and CTRL
north of Regents Canal. New structures include Wharf Road temporary bridge
over Regents Canal, West Coast Main Line (WCML) connection bridges over
MML and cross-site viaduct to North London Line (NLL). Thameslink Tunnels
between Thameslink Station Box and East Coast Main Line (ECML) are being
constructed and a bridge over the ECML and the West London Portal.
Where the new CTRL lines enter St Pancras, they will pass directly over
the Kings Cross Thameslink Tunnel. ITM were awarded a contract to install
our I-ris System to
monitor the Thameslink Tunnel. 5 Leica TC1800 Total Stations were installed
intersecting over 600 prisms installed around the tunnel. The system represents
the largest installation of robotic Total Stations in a tunnel in the UK.
To ensure that the data is transferred safely to the surface PC’s, a fibre-optic
link eliminates any potential safety or interference risks.
In addition to the tunnel monitoring system, we also installed vibration monitors connected back to the monitoring PC, Tiltmeters and Crackmeters, and a series of Inclinometer/Extensometers to monitor settlement/heave and lateral movements within the substrata ahead of the tunnel bore.
Equipment Installed:
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