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Papers are presented in the following sections: European keynote papers (4 papers); British Tunnelling Society (3 papers); Pipejacking innovation (4 papers); Tunnelling case studies (4 papers); Tunnel planning, design and construction processes (4 papers); Tunnelling for utilities I and II (7 papers); Safety and risk management I and II (7 papers); Piling and anchorages - design and performance (3 papers); Pile behaviour, specification and testing (3 papers); Underground space design I and II (6 papers); Box jacking (3 papers); Practical aspects of tunnelling I and II (9 papers); Soil improvement case histories (3 papers); Piling and reinforced wall case histories (3 papers); and Effects of tunnelling (4 papers). There are author and subject indexes, as well as exhibitors' contact details., Papers are presented in the following sections: European keynote papers (4 papers); British Tunnelling Society (3 papers); Pipejacking innovation (4 papers); Tunnelling case studies (4 papers); Tunnel planning, design and construction processes (4 papers); Tunnelling for utilities I and II (7 papers); Safety and risk management I and II (7 papers); Piling and anchorages - design and performance (3 papers); Pile behaviour, specification and testing (3 papers); Underground space design I and II (6 papers); Box jacking (3 papers); Practical aspects of tunnelling I and II (9 papers); Soil improvement case histories (3 papers); Piling and reinforced wall case histories (3 papers); and Effects of tunnelling (4 papers). There are author and subject indexes, as well as exhibitors' contact details.

When it was constructed (between 1794 and 1811), the 5.2 km tunnel on the Huddersfield canal in northern England was the longest in the world. The canal closed in 1944 and renovation of the tunnel began in 1999. The scope of repair work is briefly described and details are given of the assessment and implementation of support requirements to stabilise unlined sections and repair damage to the original masonry lining as a result of ground movement. Rock bolting and sprayed-concrete linings were designed and areas of floor heave repaired and stabilised., When it was constructed (between 1794 and 1811), the 5.2 km tunnel on the Huddersfield canal in northern England was the longest in the world. The canal closed in 1944 and renovation of the tunnel began in 1999. The scope of repair work is briefly described and details are given of the assessment and implementation of support requirements to stabilise unlined sections and repair damage to the original masonry lining as a result of ground movement. Rock bolting and sprayed-concrete linings were designed and areas of floor heave repaired and stabilised.

A virtual reality tool has been developed which allows disaster scenes in and around underground structures to be visualised. The Diabolo VR software can be used to assess the impact of a design on public safety and rescue alternatives, as well as for presenting design alternatives to decision-makers. This approach has been used for the Groene Hart high-speed rail tunnel in the Netherlands. Long before the structures are opened to the public, the same virtual reality environment can be used to train emergency response and rescue personnel. However, its use for reconstruction or analysis following an incident might generate problems such as false assumptions or psychological stress., A virtual reality tool has been developed which allows disaster scenes in and around underground structures to be visualised. The Diabolo VR software can be used to assess the impact of a design on public safety and rescue alternatives, as well as for presenting design alternatives to decision-makers. This approach has been used for the Groene Hart high-speed rail tunnel in the Netherlands. Long before the structures are opened to the public, the same virtual reality environment can be used to train emergency response and rescue personnel. However, its use for reconstruction or analysis following an incident might generate problems such as false assumptions or psychological stress.

The 680 km motorway, from the western port of Igoumenitsa to the Turkish border in the east, will include 77 twin tunnels through varying ground and groundwater conditions: geologically Recent landslide areas, thrust zones, molasse, limestones, marbles, gneisses, granites, schists, ophiolites, flysch, claystones and phyllites. Issues related to the management, design and construction of these bored and cut-and-cover tunnels are discussed. The length, construction method, ground conditions and status of each tunnel is listed, the geology of each section of the route summarised and general information given on the rock mass classification systems used, the bored tunnel portals, primary support and final linings, the cut-and-cover tunnels, and tunnel services., The 680 km motorway, from the western port of Igoumenitsa to the Turkish border in the east, will include 77 twin tunnels through varying ground and groundwater conditions: geologically Recent landslide areas, thrust zones, molasse, limestones, marbles, gneisses, granites, schists, ophiolites, flysch, claystones and phyllites. Issues related to the management, design and construction of these bored and cut-and-cover tunnels are discussed. The length, construction method, ground conditions and status of each tunnel is listed, the geology of each section of the route summarised and general information given on the rock mass classification systems used, the bored tunnel portals, primary support and final linings, the cut-and-cover tunnels, and tunnel services.

An axi-symmetrical 3D finite element model produced patterns of stress component distribution in the rock mass around the tunnel including the rock ahead of the flat face, which is in triaxial compression. Displacements produced by the driving of the tunnel were calculated and analysed and a curve presented of radial displacements of the tunnel surface in the vicinity of the face. From correlation analysis of the radial displacements, a regression equation was obtained for the coefficient of transfer from 3D to 2D stress state. The coefficient can be used as a multiplier for the components of the initial stress state of a rock mass that are required for the design of the tunnel lining., An axi-symmetrical 3D finite element model produced patterns of stress component distribution in the rock mass around the tunnel including the rock ahead of the flat face, which is in triaxial compression. Displacements produced by the driving of the tunnel were calculated and analysed and a curve presented of radial displacements of the tunnel surface in the vicinity of the face. From correlation analysis of the radial displacements, a regression equation was obtained for the coefficient of transfer from 3D to 2D stress state. The coefficient can be used as a multiplier for the components of the initial stress state of a rock mass that are required for the design of the tunnel lining.

The most challenging section of the new water main, through the congested urban environment of SE London, involved: a 285 m long pipe jack through very variable ground of the Woolwich Formation; a shallow-cover crossing under a key commuter rail route, with monitoring of ground movement; construction of a thrust chamber in sheet pile caissons, with dewatering of sand lenses containing pressurised groundwater; and construction of a deep reception pit and permanent shaft by underpinning, completed in compressed air. The ground conditions encountered are reviewed, identified risks summarised and construction methods outlined., The most challenging section of the new water main, through the congested urban environment of SE London, involved: a 285 m long pipe jack through very variable ground of the Woolwich Formation; a shallow-cover crossing under a key commuter rail route, with monitoring of ground movement; construction of a thrust chamber in sheet pile caissons, with dewatering of sand lenses containing pressurised groundwater; and construction of a deep reception pit and permanent shaft by underpinning, completed in compressed air. The ground conditions encountered are reviewed, identified risks summarised and construction methods outlined.

A method is proposed for evaluating the safety factor for a circular shallow-tunnel lining undergoing additional surface loading. The method is based on analytical solution of the elasticity theory plane contact problem for a circular ring. After determining the maximum compressive and tensile stresses on the internal lining cross-section caused by the rock mass and surface load, the safety factor is determined by applying structural strength conditions. Account is taken of the influence of the rocks' rheological properties by applying linear creep theory using the variable modules method., A method is proposed for evaluating the safety factor for a circular shallow-tunnel lining undergoing additional surface loading. The method is based on analytical solution of the elasticity theory plane contact problem for a circular ring. After determining the maximum compressive and tensile stresses on the internal lining cross-section caused by the rock mass and surface load, the safety factor is determined by applying structural strength conditions. Account is taken of the influence of the rocks' rheological properties by applying linear creep theory using the variable modules method.

Two sections of the brick- and masonry-lined UK railway tunnel, originally opened in 1849, were later supported by the installation of wrought iron ribs infilled with brick. Studies concluded that the arches were not contributing to the support provided by the secondary lining and that they should be completely removed, as they were highly corroded. Detailed design studies recommended installation of 8-12 m long rock dowels on a regular pattern to maintain the stability of the primary lining while the secondary brick lining was removed and stainless steel mesh installed. Voids above the crown should be grouted with lightweight aggregates to reduce the risk of upward movement leading to further sidewall movement. Construction is taking place during periods of restricted night-time access; unexpected areas of failed primary lining are being supported with steel lattice arch girders and sprayed fibre-reinforced concrete., Two sections of the brick- and masonry-lined UK railway tunnel, originally opened in 1849, were later supported by the installation of wrought iron ribs infilled with brick. Studies concluded that the arches were not contributing to the support provided by the secondary lining and that they should be completely removed, as they were highly corroded. Detailed design studies recommended installation of 8-12 m long rock dowels on a regular pattern to maintain the stability of the primary lining while the secondary brick lining was removed and stainless steel mesh installed. Voids above the crown should be grouted with lightweight aggregates to reduce the risk of upward movement leading to further sidewall movement. Construction is taking place during periods of restricted night-time access; unexpected areas of failed primary lining are being supported with steel lattice arch girders and sprayed fibre-reinforced concrete.

The Large Hadron Collider (LHC) in Switzerland will be housed in existing tunnels of the Large Electron-Positron (LEP) collider, but substantial new underground structures will be needed to assemble and install equipment. Package 3a included construction of a 51 m deep shaft, 3.2 km of new tunnels and 11 caverns or chambers. Excavation of the shaft through moraine into the underlying molasse was protected by diaphragm walls and supported by reinforced sprayed concrete. Tunnels were excavated by roadheaders with a range of support methods. The operations were geographically dispersed and required complex interaction over continuing LEP research, exposure to radiation, checking of dismantled items for radiation, protection of existing facilities, identification of uncharted services structures and liaison with diverse individuals and interest groups. The working arrangements and formal changes adopted are described., The Large Hadron Collider (LHC) in Switzerland will be housed in existing tunnels of the Large Electron-Positron (LEP) collider, but substantial new underground structures will be needed to assemble and install equipment. Package 3a included construction of a 51 m deep shaft, 3.2 km of new tunnels and 11 caverns or chambers. Excavation of the shaft through moraine into the underlying molasse was protected by diaphragm walls and supported by reinforced sprayed concrete. Tunnels were excavated by roadheaders with a range of support methods. The operations were geographically dispersed and required complex interaction over continuing LEP research, exposure to radiation, checking of dismantled items for radiation, protection of existing facilities, identification of uncharted services structures and liaison with diverse individuals and interest groups. The working arrangements and formal changes adopted are described.

There are often problems with the specification of shotcrete performance requirements for deep mine tunnels in South Africa: rock mechanics staff must specify criteria that can be tested by civil engineering staff in the laboratory to give unambiguous results using the same terminology. A methodology has been devised whereby if the required support pressure and anticipated deformation can be estimated then simple formulae can be used to produce first estimates for required shotcrete thickness, cube strength and energy of deformation in a slab test. This permits a specification to be drafted in terms readily understood by mine personnel, with test criteria for laboratory work. If a defined minimum load can be achieved consistently over a specified beam deflection distance in the laboratory test then the material meets the support criteria required, but if at any point over the deformation range the carried load falls below the specified minimum then it fails. The methodology has been applied in a number of cases with reasonable success., There are often problems with the specification of shotcrete performance requirements for deep mine tunnels in South Africa: rock mechanics staff must specify criteria that can be tested by civil engineering staff in the laboratory to give unambiguous results using the same terminology. A methodology has been devised whereby if the required support pressure and anticipated deformation can be estimated then simple formulae can be used to produce first estimates for required shotcrete thickness, cube strength and energy of deformation in a slab test. This permits a specification to be drafted in terms readily understood by mine personnel, with test criteria for laboratory work. If a defined minimum load can be achieved consistently over a specified beam deflection distance in the laboratory test then the material meets the support criteria required, but if at any point over the deformation range the carried load falls below the specified minimum then it fails. The methodology has been applied in a number of cases with reasonable success.

The lining designs adopted for two 5.512 m diameter, 1 150 m deep shafts through squeezing rock at Boulby mine in England have twice failed. The shafts were sunk in the period 1968-1974, relined through the marl zone in 1983-1986 and again relined in the same zone in 1998-2001. Compact reinforced composite cementitious materials have been used to produce high-strength concrete blocks, double rings of which are supported on steel decks suspended by rods from the concrete lining above. Plywood squeeze packs are located radially between the blocks, allowing radial movement under ground loading to be accommodated more favourably than by a rigid concrete system. It is thought to be the first time this method has been used for a permanent lining. Concrete specifications, contract requirements, mix design, block manufacture, quality control and performance aspects are discussed., The lining designs adopted for two 5.512 m diameter, 1 150 m deep shafts through squeezing rock at Boulby mine in England have twice failed. The shafts were sunk in the period 1968-1974, relined through the marl zone in 1983-1986 and again relined in the same zone in 1998-2001. Compact reinforced composite cementitious materials have been used to produce high-strength concrete blocks, double rings of which are supported on steel decks suspended by rods from the concrete lining above. Plywood squeeze packs are located radially between the blocks, allowing radial movement under ground loading to be accommodated more favourably than by a rigid concrete system. It is thought to be the first time this method has been used for a permanent lining. Concrete specifications, contract requirements, mix design, block manufacture, quality control and performance aspects are discussed.

Jacked box tunnelling is a non-intrusive method of constructing new concrete subways, culverts or under-bridges beneath existing railway infrastructure. The method developed from pipe jacking, but the largest jacked tunnel in the UK to date was 50 m long, 23 m wide and 9.5 m high. The technology necessary to control ground disturbance and to maintain safe, unimpeded operation of the railway is explained and recent examples are presented from Lewisham in London, Dorney in Berkshire and Boston in the USA., Jacked box tunnelling is a non-intrusive method of constructing new concrete subways, culverts or under-bridges beneath existing railway infrastructure. The method developed from pipe jacking, but the largest jacked tunnel in the UK to date was 50 m long, 23 m wide and 9.5 m high. The technology necessary to control ground disturbance and to maintain safe, unimpeded operation of the railway is explained and recent examples are presented from Lewisham in London, Dorney in Berkshire and Boston in the USA.

A two-lane tunnel for the Ramsgate harbour approach road was the first in the UK to use the prevault tunnelling system. Groundborne noise and vibration during tunnelling was assessed by measurements on open ground and inside houses, in order to validate methods for predicting these impacts. Vibration during excavation and construction of the primary lining by the prevault system was slightly lower than that recorded at other chalk tunnelling sites, but this appears to have been a reflection of the grade of chalk excavated rather than the method. The greatest vibration was caused by the use of limpet vibrators to compact the cast-in-situ secondary concrete lining. The most significant environmental disturbance was from noise: the subjective response of residents suggested that quantification by A-weighting was not the most appropriate method, particularly for noise at night; C-weighting, which gives more emphasis to low frequencies, might be more suitable., A two-lane tunnel for the Ramsgate harbour approach road was the first in the UK to use the prevault tunnelling system. Groundborne noise and vibration during tunnelling was assessed by measurements on open ground and inside houses, in order to validate methods for predicting these impacts. Vibration during excavation and construction of the primary lining by the prevault system was slightly lower than that recorded at other chalk tunnelling sites, but this appears to have been a reflection of the grade of chalk excavated rather than the method. The greatest vibration was caused by the use of limpet vibrators to compact the cast-in-situ secondary concrete lining. The most significant environmental disturbance was from noise: the subjective response of residents suggested that quantification by A-weighting was not the most appropriate method, particularly for noise at night; C-weighting, which gives more emphasis to low frequencies, might be more suitable.

Experienced tunnel engineers familiar with the problems of working close to active railway tunnels are rarely involved in the planning stages of a project, so that measures to avoid or mitigate adverse effects are often not proposed until a late stage when they cannot readily be accommodated. The possible effects of development on tunnels are discussed and the types of monitoring suitable for ensuring that potentially critical situations do not develop are described. London case histories illustrating typical concerns include: the effect of a deep escalator to the Angel station, introduced at a late stage, on the structural design of an office block; predictions of ground movement around the Wanstead station escalators during construction of the George Green cut-and-cover tunnel; and the monitoring and assessment of heave and distortion of the Bakerloo Line tunnels with unloading during excavation for the Waterloo International rail terminal., Experienced tunnel engineers familiar with the problems of working close to active railway tunnels are rarely involved in the planning stages of a project, so that measures to avoid or mitigate adverse effects are often not proposed until a late stage when they cannot readily be accommodated. The possible effects of development on tunnels are discussed and the types of monitoring suitable for ensuring that potentially critical situations do not develop are described. London case histories illustrating typical concerns include: the effect of a deep escalator to the Angel station, introduced at a late stage, on the structural design of an office block; predictions of ground movement around the Wanstead station escalators during construction of the George Green cut-and-cover tunnel; and the monitoring and assessment of heave and distortion of the Bakerloo Line tunnels with unloading during excavation for the Waterloo International rail terminal.

Replacing a laser alignment system with a gyro and robotic total station will allow continuous monitoring for spatial angular orientation - heading, pitch and roll - as well as x, y and z co-ordinates. A mechanical gyrocompass, used from 1989 to 1999, enabled the tunnel boring machine to be monitored during advances along curved alignments in pipe-jack tunnels with minimal manual input. Its replacement with an advanced-technology gyro will provide greater reliability and higher accuracy. In conventional tunnels with a fixed primary lining, the concept is further extended by linking an autotracking robotic total station to the gyro. This is intended to supply the TBM operator with information on machine attitude in both vertical and horizontal planes under all operating conditions. A broken sight-line will not affect the view of real-time orientation vectors and the TBM will continue to operate on spatial vectors alone until the sight-line is restored., Replacing a laser alignment system with a gyro and robotic total station will allow continuous monitoring for spatial angular orientation - heading, pitch and roll - as well as x, y and z co-ordinates. A mechanical gyrocompass, used from 1989 to 1999, enabled the tunnel boring machine to be monitored during advances along curved alignments in pipe-jack tunnels with minimal manual input. Its replacement with an advanced-technology gyro will provide greater reliability and higher accuracy. In conventional tunnels with a fixed primary lining, the concept is further extended by linking an autotracking robotic total station to the gyro. This is intended to supply the TBM operator with information on machine attitude in both vertical and horizontal planes under all operating conditions. A broken sight-line will not affect the view of real-time orientation vectors and the TBM will continue to operate on spatial vectors alone until the sight-line is restored.

The compressibility and permeability characteristics of sand/foam mixtures were studied using a Rowe cell and their shear strength characteristics using shear box tests. The tests demonstrated that the mixtures can exist at high void ratios at stresses up to about 200 kPa. At these high void ratios the sands also exhibit low angles of friction. Both the high compressibility and the low frictional strength have important implications for the use of foams in tunnelling operations. Foams may also serve to reduce the permeability of a sand. Conditioning with bentonite and polymers has also been examined: although they have a smaller influence on compressibility and strength characteristics when used alone, they can play an important role in stabilising and modifying a sand/foam mixture., The compressibility and permeability characteristics of sand/foam mixtures were studied using a Rowe cell and their shear strength characteristics using shear box tests. The tests demonstrated that the mixtures can exist at high void ratios at stresses up to about 200 kPa. At these high void ratios the sands also exhibit low angles of friction. Both the high compressibility and the low frictional strength have important implications for the use of foams in tunnelling operations. Foams may also serve to reduce the permeability of a sand. Conditioning with bentonite and polymers has also been examined: although they have a smaller influence on compressibility and strength characteristics when used alone, they can play an important role in stabilising and modifying a sand/foam mixture.

The statutory background to the provision of self-rescuers and breathing apparatus in the UK is set out and relevant British/European standards are noted. Atmospheric contaminants presenting an acute risk to workers underground are listed. Three types of self-rescuer are commonly available in the UK: filter self-rescuers to remove carbon monoxide, compressed or chemical oxygen self-rescuers and compressed air suppliers, which typically last only 5-15 mins. Breathing apparatus for rescue teams requires much greater duration than self-rescuers. Issues discussed include factors affecting duration, penetration distance, voice communication, storage of self-rescuers, inspection and maintenance of respiratory equipment, training and oxygen toxicity. A commercially available compressed oxygen self-rescuer has been modified to produce a prototype capable of providing a respirable gas supply at all working pressures., The statutory background to the provision of self-rescuers and breathing apparatus in the UK is set out and relevant British/European standards are noted. Atmospheric contaminants presenting an acute risk to workers underground are listed. Three types of self-rescuer are commonly available in the UK: filter self-rescuers to remove carbon monoxide, compressed or chemical oxygen self-rescuers and compressed air suppliers, which typically last only 5-15 mins. Breathing apparatus for rescue teams requires much greater duration than self-rescuers. Issues discussed include factors affecting duration, penetration distance, voice communication, storage of self-rescuers, inspection and maintenance of respiratory equipment, training and oxygen toxicity. A commercially available compressed oxygen self-rescuer has been modified to produce a prototype capable of providing a respirable gas supply at all working pressures.

The reasons for conditioning and the properties and uses of various conditioning agents and lubricants are reviewed. Bentonite slurries maintain dispersion and provide lubrication for both slurry shield tunnelling and pipe jacking, if necessary with additives or flocculants to enhance filter-cake formation, improve the performance of separation plants or inhibit clay swelling. The effectiveness of foam or foamed bentonite for pipe jacking is not known. For tunnelling with EPBM shields, conditioning agents range from water through bentonite slurries to various polymers and especially foams, injected at the face, in the working chamber or even in the screw conveyor. Additives need to be correctly chosen for the type of soil encountered and tunnelling machines must be provided with adequate facilities for adding the agents in controlled dosages and mixing them sufficiently with the soil., The reasons for conditioning and the properties and uses of various conditioning agents and lubricants are reviewed. Bentonite slurries maintain dispersion and provide lubrication for both slurry shield tunnelling and pipe jacking, if necessary with additives or flocculants to enhance filter-cake formation, improve the performance of separation plants or inhibit clay swelling. The effectiveness of foam or foamed bentonite for pipe jacking is not known. For tunnelling with EPBM shields, conditioning agents range from water through bentonite slurries to various polymers and especially foams, injected at the face, in the working chamber or even in the screw conveyor. Additives need to be correctly chosen for the type of soil encountered and tunnelling machines must be provided with adequate facilities for adding the agents in controlled dosages and mixing them sufficiently with the soil.

A description is given of field measurement methods used during jacking of water pipes for the Yangluo power plant at Wuhan in China; factors to be taken into account when calculating pipe stability, stiffness and strength are discussed and a new approach to wall thickness design proposed., A description is given of field measurement methods used during jacking of water pipes for the Yangluo power plant at Wuhan in China; factors to be taken into account when calculating pipe stability, stiffness and strength are discussed and a new approach to wall thickness design proposed.

Some current design methods are reviewed and the use of more sophisticated constitutive models for sprayed concrete considered, with the example of field data from London's Heathrow Express project. The importance of more detailed modelling has been recognised for some time, but the complexity of the problem has hindered the development of reliable models. Their inherent simplifications make analytical methods inadequate, though still useful in initial design and as independent checks on the results from numerical modelling. Initial results of numerical analysis support the view that the constitutive model adopted for sprayed concrete has a major influence on the stresses predicted in the lining. Incorporating nonlinear stress-strain behaviour and creep into the numerical model leads to considerable reductions in the predicted axial forces and, to a greater degree, bending moments., Some current design methods are reviewed and the use of more sophisticated constitutive models for sprayed concrete considered, with the example of field data from London's Heathrow Express project. The importance of more detailed modelling has been recognised for some time, but the complexity of the problem has hindered the development of reliable models. Their inherent simplifications make analytical methods inadequate, though still useful in initial design and as independent checks on the results from numerical modelling. Initial results of numerical analysis support the view that the constitutive model adopted for sprayed concrete has a major influence on the stresses predicted in the lining. Incorporating nonlinear stress-strain behaviour and creep into the numerical model leads to considerable reductions in the predicted axial forces and, to a greater degree, bending moments.

The new UK rail link is being constructed alongside and above the existing 872 m long brick-lined Saltwood railway tunnel, built in 1843, which currently carries the continental and domestic rail traffic. Its original construction is outlined and the studies undertaken to quantify potential impacts are described. A comprehensive monitoring system was installed and used to provide a real-time picture of construction impacts, while pre-excavation remedial work included extensive grouting. The effective interaction and cooperation between design and construction teams allowed the scope of the work to be optimised and the programme achieved with no loss of function., The new UK rail link is being constructed alongside and above the existing 872 m long brick-lined Saltwood railway tunnel, built in 1843, which currently carries the continental and domestic rail traffic. Its original construction is outlined and the studies undertaken to quantify potential impacts are described. A comprehensive monitoring system was installed and used to provide a real-time picture of construction impacts, while pre-excavation remedial work included extensive grouting. The effective interaction and cooperation between design and construction teams allowed the scope of the work to be optimised and the programme achieved with no loss of function.

The evolving use of earth pressure-balance tunnelling machines is reviewed with reference to the Greater Cairo Wastewater project and the 8 km Portsmouth water transfer tunnel. On the Cairo scheme, commenced in 1985 to replace the old sewer system, problems with the use of compressed air and slurry TBMs led to the adoption of the relatively new EPB method, which involved excavating spoil and removing it from the sealed chamber behind the cutting wheel via an Archimedian screw. The length and pitch of the screw created a plug of material that allowed pressure to build up, supporting the excavated face. Four Lovat machines constructed 26 km of tunnel in water-bearing sands at rates of progress previously unknown. The choice of EPB machines for tunnelling through chalk and overlying clays and sands at Portsmouth is discussed and the improvements over the machines used in Cairo are described., The evolving use of earth pressure-balance tunnelling machines is reviewed with reference to the Greater Cairo Wastewater project and the 8 km Portsmouth water transfer tunnel. On the Cairo scheme, commenced in 1985 to replace the old sewer system, problems with the use of compressed air and slurry TBMs led to the adoption of the relatively new EPB method, which involved excavating spoil and removing it from the sealed chamber behind the cutting wheel via an Archimedian screw. The length and pitch of the screw created a plug of material that allowed pressure to build up, supporting the excavated face. Four Lovat machines constructed 26 km of tunnel in water-bearing sands at rates of progress previously unknown. The choice of EPB machines for tunnelling through chalk and overlying clays and sands at Portsmouth is discussed and the improvements over the machines used in Cairo are described.

The 18 km tunnel through the Kallidromo mountains in central Greece is part of a new high-speed rail link between Athens and Thessaloniki. Each bore has a face area of up to 85 m2 and maximum overburden is 540 m. The initial section has been driven through Pliocene and Pleistocene sediments with poor mechanical properties, composed mainly of slickensided clay and loose sand. The cover-and-cut portals were pre-supported by bored piles. Tunnelling encountered sections with high convergence, significant groundwater inflow and instability of the working face. Support systems, designed following site-specific numerical analysis, proved adequate for the conditions but local reconstruction was needed to obtain the required geometry. Special elements included forepoling umbrellas, spiling rods, micropiles, grouted fibreglass dowels, long anchors and an elephant-foot temporary invert., The 18 km tunnel through the Kallidromo mountains in central Greece is part of a new high-speed rail link between Athens and Thessaloniki. Each bore has a face area of up to 85 m2 and maximum overburden is 540 m. The initial section has been driven through Pliocene and Pleistocene sediments with poor mechanical properties, composed mainly of slickensided clay and loose sand. The cover-and-cut portals were pre-supported by bored piles. Tunnelling encountered sections with high convergence, significant groundwater inflow and instability of the working face. Support systems, designed following site-specific numerical analysis, proved adequate for the conditions but local reconstruction was needed to obtain the required geometry. Special elements included forepoling umbrellas, spiling rods, micropiles, grouted fibreglass dowels, long anchors and an elephant-foot temporary invert.

As part of a flood alleviation scheme on the River Thames in southern England, a large box culvert was jacked through an embankment under the Great Western railway. To maintain the embankment's stability, ground freezing was adopted. The structural strength and deformation of the frozen ground around the culvert was calculated to ensure its support would be adequate during the jacking process. Its thermal behaviour was also predicted to ensure freeze growth could be controlled and would be satisfactory. Ground heave and thaw settlement estimates were made to ensure the level and alignment of the railway tracks could be maintained during jacking. Performance monitoring gave actual values close to those predicted and the project was successfully completed in August 1999., As part of a flood alleviation scheme on the River Thames in southern England, a large box culvert was jacked through an embankment under the Great Western railway. To maintain the embankment's stability, ground freezing was adopted. The structural strength and deformation of the frozen ground around the culvert was calculated to ensure its support would be adequate during the jacking process. Its thermal behaviour was also predicted to ensure freeze growth could be controlled and would be satisfactory. Ground heave and thaw settlement estimates were made to ensure the level and alignment of the railway tracks could be maintained during jacking. Performance monitoring gave actual values close to those predicted and the project was successfully completed in August 1999.

The Prestressed and Precast Concrete Segmental Lining (P&PCSL) provides a prestressed concrete structure by tensioning and anchoring the unbonded prestressing steel after its installation into the winding sheath within the precast concrete. The unbonded prestressing steel decreases tensioning friction loss so that the anchoring position is at only one location on the lining annulus. The X-shaped anchoring device is manufactured from cast iron and embedded in the precast concrete in advance. The lining is easily erected by pressing the shield jacks into contact with the existing back lining; no mechanical joints or bolts are needed, as the introduction of prestress integrates the segments into a single unit. The results of basic performance tests and initial construction projects are reported., The Prestressed and Precast Concrete Segmental Lining (P&PCSL) provides a prestressed concrete structure by tensioning and anchoring the unbonded prestressing steel after its installation into the winding sheath within the precast concrete. The unbonded prestressing steel decreases tensioning friction loss so that the anchoring position is at only one location on the lining annulus. The X-shaped anchoring device is manufactured from cast iron and embedded in the precast concrete in advance. The lining is easily erected by pressing the shield jacks into contact with the existing back lining; no mechanical joints or bolts are needed, as the introduction of prestress integrates the segments into a single unit. The results of basic performance tests and initial construction projects are reported.

The largest railway tunnel ever built in the UK, at 3.2 km long and 6.53 m in internal radius, the tunnel through the chalk of the North Downs is also the first major NATM tunnel to be designed and built in the UK since 1994. Significant savings have been achieved through value engineering of the tunnel lining and the optimising ability of an on-site design team. Integration of the project manager's and contractor's designers has allowed fast-track evaluation and assessment of design verification data. The three main areas of the design with potential for a significant effect on costs were the geotechnical parameters, a revised waterproofing philosophy and a contribution to long-term support by the primary lining. The results of settlement monitoring and geotechnical investigation are presented., The largest railway tunnel ever built in the UK, at 3.2 km long and 6.53 m in internal radius, the tunnel through the chalk of the North Downs is also the first major NATM tunnel to be designed and built in the UK since 1994. Significant savings have been achieved through value engineering of the tunnel lining and the optimising ability of an on-site design team. Integration of the project manager's and contractor's designers has allowed fast-track evaluation and assessment of design verification data. The three main areas of the design with potential for a significant effect on costs were the geotechnical parameters, a revised waterproofing philosophy and a contribution to long-term support by the primary lining. The results of settlement monitoring and geotechnical investigation are presented.

The UK's largest railway tunnel is on target to be completed five months early and more than #10 000 000 below budget, a success achieved through innovation, value engineering, integrated design and construction, and effective project management. The construction process and logistics are described, including tunnel excavation, primary and secondary lining, tunnel waterproofing, construction of walkway supports, back grouting and completion of the portal canopies. The management of the project is examined and the process of contractor self-certification discussed., The UK's largest railway tunnel is on target to be completed five months early and more than #10 000 000 below budget, a success achieved through innovation, value engineering, integrated design and construction, and effective project management. The construction process and logistics are described, including tunnel excavation, primary and secondary lining, tunnel waterproofing, construction of walkway supports, back grouting and completion of the portal canopies. The management of the project is examined and the process of contractor self-certification discussed.

The 147 m tunnel, part of a new link between the Forth and Clyde Canal and the Union Canal, was constructed using a single-pass sprayed concrete lining in a mixed face of glacial till overlying Lower Coal Measures of varying strength. A shallow, unfilled stoop-and-room fireclay mine underlies the tunnel. A number of boreholes were drilled into the mine to ascertain the rock quality in the roof and pillars, and ultrasonic surveys were carried out to determine the condition of the workings. The risks and effects of a mine collapse were assessed and design measures undertaken to ensure the structural integrity of the tunnel, whose construction is described., The 147 m tunnel, part of a new link between the Forth and Clyde Canal and the Union Canal, was constructed using a single-pass sprayed concrete lining in a mixed face of glacial till overlying Lower Coal Measures of varying strength. A shallow, unfilled stoop-and-room fireclay mine underlies the tunnel. A number of boreholes were drilled into the mine to ascertain the rock quality in the roof and pillars, and ultrasonic surveys were carried out to determine the condition of the workings. The risks and effects of a mine collapse were assessed and design measures undertaken to ensure the structural integrity of the tunnel, whose construction is described.

A study has been undertaken by the UK Health and Safety Executive to identify the materials used as soil conditioning agents and the hazards associated with those materials. The survey is neither exhaustive nor fully comprehensive, nor does it cover fire risk or environmental effects. The main materials in use are bentonites, polymers and foaming agents; dispersants and thinners include lignosulphonates and complex phosphates. Typical uses and hazards associated with various conditioners are listed, followed by the uses and identified health hazards of individual constituents. Soil conditioners may contain materials which have occupational exposure limits and should be accompanied by safety data sheets when dangerous. The most frequent health effect found in the study was irritation of the skin and eyes; other problems included effects on skin with longer-term exposure, depression of the central nervous system by solvents, dust inhalation, vapour inhalation and the generation of slipping hazards. A few constituents were known to be toxic or mutagenic., A study has been undertaken by the UK Health and Safety Executive to identify the materials used as soil conditioning agents and the hazards associated with those materials. The survey is neither exhaustive nor fully comprehensive, nor does it cover fire risk or environmental effects. The main materials in use are bentonites, polymers and foaming agents; dispersants and thinners include lignosulphonates and complex phosphates. Typical uses and hazards associated with various conditioners are listed, followed by the uses and identified health hazards of individual constituents. Soil conditioners may contain materials which have occupational exposure limits and should be accompanied by safety data sheets when dangerous. The most frequent health effect found in the study was irritation of the skin and eyes; other problems included effects on skin with longer-term exposure, depression of the central nervous system by solvents, dust inhalation, vapour inhalation and the generation of slipping hazards. A few constituents were known to be toxic or mutagenic.

The reversal of hydrostatic pressure in water tunnels can create structural instability. Remote inspection techniques have successfully minimised this risk as well as decreasing periods of down-time. Improvements in remotely operated vehicles and the integration of specialised inspection techniques have made it possible to conduct inspections of flooded tunnels and pipes for distances up to 10 km from a single access point. Techniques have included innovative applications of remote sensing technologies such as temperature probes, ground-penetrating radar, acoustics and video analysis. ASI Marine's Pipeliner vehicles are used in gravity flow intakes and outfalls while the larger ASI Mantaro is generally applied to pressure tunnels, due to the greater length involved. Cases from Peru, Finland, Chile and New Zealand are described., The reversal of hydrostatic pressure in water tunnels can create structural instability. Remote inspection techniques have successfully minimised this risk as well as decreasing periods of down-time. Improvements in remotely operated vehicles and the integration of specialised inspection techniques have made it possible to conduct inspections of flooded tunnels and pipes for distances up to 10 km from a single access point. Techniques have included innovative applications of remote sensing technologies such as temperature probes, ground-penetrating radar, acoustics and video analysis. ASI Marine's Pipeliner vehicles are used in gravity flow intakes and outfalls while the larger ASI Mantaro is generally applied to pressure tunnels, due to the greater length involved. Cases from Peru, Finland, Chile and New Zealand are described.

Highway minitunnels, also referred to as limited facility tunnels, are small-diameter structures accessible only to light vehicles and with a typical headroom of 2.6 m. They may be used to segregate road users so as to maximise surface space for pedestrians and cyclists, to alleviate congestion hot-spots, to by-pass complex junctions or to improve interchange facilities for transferring from cars to public transport. Research to develop design guidelines has addressed a range of specific issues: possible construction methods, operational issues such as signs, and safety issues such as access for emergency services. A full-scale vehicle simulator has been used to examine the responses of drivers to a range of virtual minitunnels., Highway minitunnels, also referred to as limited facility tunnels, are small-diameter structures accessible only to light vehicles and with a typical headroom of 2.6 m. They may be used to segregate road users so as to maximise surface space for pedestrians and cyclists, to alleviate congestion hot-spots, to by-pass complex junctions or to improve interchange facilities for transferring from cars to public transport. Research to develop design guidelines has addressed a range of specific issues: possible construction methods, operational issues such as signs, and safety issues such as access for emergency services. A full-scale vehicle simulator has been used to examine the responses of drivers to a range of virtual minitunnels.

The inhibition of clay swelling by pipejacking lubricants was investigated, as well as the effects of conditioning agents on some basic properties of clay soils and machine-soil interactions relevant to tunnelling machine operations. The effects of different inhibiting agents on swelling, index properties and undrained shear strength over a range of ground conditions were measured. A model earth-pressure balance (EPB) screw conveyor has been built for use in investigating the mechanics of operation and the effects of conditioning agents on performance. The research is aimed at providing guidance for the formulation of pipejacking lubricant fluids to minimise problems due to swelling ground during construction and for conditioning of clay soils to improve their properties for tunnelling machine operators., The inhibition of clay swelling by pipejacking lubricants was investigated, as well as the effects of conditioning agents on some basic properties of clay soils and machine-soil interactions relevant to tunnelling machine operations. The effects of different inhibiting agents on swelling, index properties and undrained shear strength over a range of ground conditions were measured. A model earth-pressure balance (EPB) screw conveyor has been built for use in investigating the mechanics of operation and the effects of conditioning agents on performance. The research is aimed at providing guidance for the formulation of pipejacking lubricant fluids to minimise problems due to swelling ground during construction and for conditioning of clay soils to improve their properties for tunnelling machine operators.

A pedestrian tunnel in Singapore, 53 m long, 9 m wide and 5.4 m high, was successfully constructed in bouldery sandstone colluvium using pipe roofing and tube-a-manchette (TAM) grouting, with minimal effect on the road and canal above. The pipe roof consisted of interconnected steel pipes of 620 mm diameter, their cores filled with cement grout. To prevent any soil collapse or water inflow, soil gaps between the pipes were grouted using the tube-a-manchette technique, involving one or two stages of injection through a pre-installed outer tube using a double-packer inner tube system. Delays in the pipe roofing led to abandonment of the proposed front jacking construction method and the adoption of head-and-bench excavation with shotcreting and installation of steel frames every 1.25 m. Ground settlement was predicted using the SAGE CRISP computer program., A pedestrian tunnel in Singapore, 53 m long, 9 m wide and 5.4 m high, was successfully constructed in bouldery sandstone colluvium using pipe roofing and tube-a-manchette (TAM) grouting, with minimal effect on the road and canal above. The pipe roof consisted of interconnected steel pipes of 620 mm diameter, their cores filled with cement grout. To prevent any soil collapse or water inflow, soil gaps between the pipes were grouted using the tube-a-manchette technique, involving one or two stages of injection through a pre-installed outer tube using a double-packer inner tube system. Delays in the pipe roofing led to abandonment of the proposed front jacking construction method and the adoption of head-and-bench excavation with shotcreting and installation of steel frames every 1.25 m. Ground settlement was predicted using the SAGE CRISP computer program.

The development of one manufacturer's roadheader, the Webster Schaeff 2000CL excavating machine, is described and illustrated. The roadheader has a distinctive articulated cutting head, which provides the mining and civil engineering industries with a small and lightweight but robust and highly manoeuvrable roadheader, capable of cutting complex shapes and operating in difficult geology or confined spaces. The machine has recently found a niche in jacked box tunnelling at Dorney in the UK and has also been used for roof and wall scaling at the Goderich salt mine in Ontario and for excavating wine caverns in California., The development of one manufacturer's roadheader, the Webster Schaeff 2000CL excavating machine, is described and illustrated. The roadheader has a distinctive articulated cutting head, which provides the mining and civil engineering industries with a small and lightweight but robust and highly manoeuvrable roadheader, capable of cutting complex shapes and operating in difficult geology or confined spaces. The machine has recently found a niche in jacked box tunnelling at Dorney in the UK and has also been used for roof and wall scaling at the Goderich salt mine in Ontario and for excavating wine caverns in California.

Twin road tunnels about 18 m in diameter are being excavated in faulted and heavily tectonised rocks on the Trans-European motorway network, using linings of sprayed and cast-in-situ concrete. A thorough re-assessment of the design was initiated in 1998, following deformations of up to 1 m radial convergence in unexpected zones of clayey ground. The ground was investigated via a pilot tunnel, supplemented by surface and subsurface drilling. Groundwater pressure was identified as a key contributor to instability. In very poor ground, a stiff initial lining was needed close to the face to limit deformation and ground failure, but too stiff a lining might attract excessive ground loads. A complex programme of instrumentation was implemented to monitor tunnel performance and verify the new design., Twin road tunnels about 18 m in diameter are being excavated in faulted and heavily tectonised rocks on the Trans-European motorway network, using linings of sprayed and cast-in-situ concrete. A thorough re-assessment of the design was initiated in 1998, following deformations of up to 1 m radial convergence in unexpected zones of clayey ground. The ground was investigated via a pilot tunnel, supplemented by surface and subsurface drilling. Groundwater pressure was identified as a key contributor to instability. In very poor ground, a stiff initial lining was needed close to the face to limit deformation and ground failure, but too stiff a lining might attract excessive ground loads. A complex programme of instrumentation was implemented to monitor tunnel performance and verify the new design.

A theodolite with a Wild GAK1 gyro attachment is difficult to operate and is unlikely to produce good-quality results without the involvement of experienced surveying operators. A fully automated system being developed at the Camborne School of Mines includes an electronic eye specifically designed to resolve the problems associated with manual observations and the recording of gyro tape oscillation data. The device incorporates two time-data capture sensors positioned at known points within the reflected swing path of the gyro, allowing sensor passing times to be recorded and automatically processed to establish the location of the gyro's centre of oscillation, from which the true north azimuth of an unknown baseline can then be calculated. The entire automated system is described and the steps for calculating the error factor are given., A theodolite with a Wild GAK1 gyro attachment is difficult to operate and is unlikely to produce good-quality results without the involvement of experienced surveying operators. A fully automated system being developed at the Camborne School of Mines includes an electronic eye specifically designed to resolve the problems associated with manual observations and the recording of gyro tape oscillation data. The device incorporates two time-data capture sensors positioned at known points within the reflected swing path of the gyro, allowing sensor passing times to be recorded and automatically processed to establish the location of the gyro's centre of oscillation, from which the true north azimuth of an unknown baseline can then be calculated. The entire automated system is described and the steps for calculating the error factor are given.

In urban areas, surface disturbance can be minimised by constructing tunnels of large cross-section from a series of small individual full-face tunnels. A new method has been developed for predicting the ground response to this multi-excavation technique, known as Multi-Micro Shield Tunnelling or MMST. A multi-trap door physical model was used to record changes in the earth pressure acting on the roof and in ground deformation at the surface and subsurface during shield driving of five parallel tunnels, simulated by opening the five trap-doors. The applicability of Terzaghi's theory for conventional prediction of earth pressure was verified and it was also shown that the distribution of shear strain in the ground varied with each step of the excavation sequence, though the distribution of maximum shear strain at the final stage of excavation was independent of excavation sequence., In urban areas, surface disturbance can be minimised by constructing tunnels of large cross-section from a series of small individual full-face tunnels. A new method has been developed for predicting the ground response to this multi-excavation technique, known as Multi-Micro Shield Tunnelling or MMST. A multi-trap door physical model was used to record changes in the earth pressure acting on the roof and in ground deformation at the surface and subsurface during shield driving of five parallel tunnels, simulated by opening the five trap-doors. The applicability of Terzaghi's theory for conventional prediction of earth pressure was verified and it was also shown that the distribution of shear strain in the ground varied with each step of the excavation sequence, though the distribution of maximum shear strain at the final stage of excavation was independent of excavation sequence.

Appendix B of British and European standard BSI:ENV 1916: 1998 on pipes and fittings of unreinforced, steel-reinforced and steel fibre-reinforced concrete raises a number of issues with regard to joints in pipe-jacked tunnels. Design methods for meeting stress requirements at the ends of pipes are discussed with regard to limitations of stress formulation, permitted variation in the design packer area, selection of characteristic values of actions, concrete failure, variation in material properties and acceptability of risks. Analytical models important for determining conditions at the contact faces are compared and observed distributions of the values of actions are compared with those derived assuming normal Gaussian distribution of variables. It is suggested that the failure mode of pipes should be considered as well as characteristic concrete strength when determining limiting contact stress and that variation in packer stiffness due to pipe loading requires further consideration of the use of mean values for material properties., Appendix B of British and European standard BSI:ENV 1916: 1998 on pipes and fittings of unreinforced, steel-reinforced and steel fibre-reinforced concrete raises a number of issues with regard to joints in pipe-jacked tunnels. Design methods for meeting stress requirements at the ends of pipes are discussed with regard to limitations of stress formulation, permitted variation in the design packer area, selection of characteristic values of actions, concrete failure, variation in material properties and acceptability of risks. Analytical models important for determining conditions at the contact faces are compared and observed distributions of the values of actions are compared with those derived assuming normal Gaussian distribution of variables. It is suggested that the failure mode of pipes should be considered as well as characteristic concrete strength when determining limiting contact stress and that variation in packer stiffness due to pipe loading requires further consideration of the use of mean values for material properties.

The tunnel was constructed under a heavily congested area of London using innovative semi-mechanised tunnelling techniques to negotiate a tortuous horizontal alignment with curves of 40 m radius. Two tunnelling machines of 2.54 m internal diameter, designed to negotiate the 25 m curves in the original contract, were used; innovative in-house systems proved highly successful and flexible through a variety of ring types and ground conditions. The machines were serviced on a round-the-clock basis from within an acoustic building with noise-tight doors and silent ventilation, designed to satisfy noise attenuation requirements at Shaft 2. During peak production a total of 60 rings were held on site, comprising up to six different types. Required progress rates were regularly exceeded and the overall time period for tunnelling was achieved., The tunnel was constructed under a heavily congested area of London using innovative semi-mechanised tunnelling techniques to negotiate a tortuous horizontal alignment with curves of 40 m radius. Two tunnelling machines of 2.54 m internal diameter, designed to negotiate the 25 m curves in the original contract, were used; innovative in-house systems proved highly successful and flexible through a variety of ring types and ground conditions. The machines were serviced on a round-the-clock basis from within an acoustic building with noise-tight doors and silent ventilation, designed to satisfy noise attenuation requirements at Shaft 2. During peak production a total of 60 rings were held on site, comprising up to six different types. Required progress rates were regularly exceeded and the overall time period for tunnelling was achieved.

The Ashford section of the new UK rail link involved 15.2 km of railway construction through rural and urban areas. Structures close to residential areas included contiguous bored-pile wall foundations for cut-and-cover tunnels and viaduct bases as well as substantial earthworks and pours of structural concrete. All activities liable to generate noise or perceptible vibration at third-party premises were regulated by the Section 61 consent procedure under the Control of Pollution Act 1974. A management plan for noise and vibration was developed within the contractor's environmental management system and there was close liaison between contractor, project manager and the local authority. The arrangements for seeking Section 61 consent and for obtaining amendments or dispensations are described, as well as the long-term and ad-hoc monitoring of noise and vibration from site activities and mitigation measures., The Ashford section of the new UK rail link involved 15.2 km of railway construction through rural and urban areas. Structures close to residential areas included contiguous bored-pile wall foundations for cut-and-cover tunnels and viaduct bases as well as substantial earthworks and pours of structural concrete. All activities liable to generate noise or perceptible vibration at third-party premises were regulated by the Section 61 consent procedure under the Control of Pollution Act 1974. A management plan for noise and vibration was developed within the contractor's environmental management system and there was close liaison between contractor, project manager and the local authority. The arrangements for seeking Section 61 consent and for obtaining amendments or dispensations are described, as well as the long-term and ad-hoc monitoring of noise and vibration from site activities and mitigation measures.

Traditional methods for designing tunnels in soft ground, such as closed-form solutions and bedded-beam models, are compared with the more complex numerical techniques for three-dimensional analysis that have become available with the development of flexible and powerful computers. Common applications of three-dimensional code are described, a practical means suggested for using such a code in the tunnel design process, and situations identified where such codes can prove invaluable in the production of a safe and economical design. The codes referred to are FLAC 2D and FLAC 3D, which have been developed for geomechanical analysis where the ground is modelled as a continuum, but any 3D numerical analysis code suitable for geomechanical analysis can be adopted for tunnel design in the way described., Traditional methods for designing tunnels in soft ground, such as closed-form solutions and bedded-beam models, are compared with the more complex numerical techniques for three-dimensional analysis that have become available with the development of flexible and powerful computers. Common applications of three-dimensional code are described, a practical means suggested for using such a code in the tunnel design process, and situations identified where such codes can prove invaluable in the production of a safe and economical design. The codes referred to are FLAC 2D and FLAC 3D, which have been developed for geomechanical analysis where the ground is modelled as a continuum, but any 3D numerical analysis code suitable for geomechanical analysis can be adopted for tunnel design in the way described.

A 310 m pipe jack for an 1 800 mm diameter sewer tunnel at Seaham Harbour in NE England was instrumented and monitored as part of a research project, to collect information on jacking loads, pipe-soil interface stresses and ground movements. Stress cells were built into the wall of a standard concrete jacking pipe, inserted about 180 m behind the tunnel boring machine, and ground movements were measured by levelling, inclinometers, extensometers and electrolevels. Bentonite lubrication, introduced after ten pipes had been installed, reduced frictional resistance by 70%. The effects of stoppages on required jacking were only significant after long breaks: a 50-60% increase was typically required to restart after the weekend. Electrolevels in a tube close to the tunnel crown were used to monitor the development of a longitudinal sub-surface settlement profile., A 310 m pipe jack for an 1 800 mm diameter sewer tunnel at Seaham Harbour in NE England was instrumented and monitored as part of a research project, to collect information on jacking loads, pipe-soil interface stresses and ground movements. Stress cells were built into the wall of a standard concrete jacking pipe, inserted about 180 m behind the tunnel boring machine, and ground movements were measured by levelling, inclinometers, extensometers and electrolevels. Bentonite lubrication, introduced after ten pipes had been installed, reduced frictional resistance by 70%. The effects of stoppages on required jacking were only significant after long breaks: a 50-60% increase was typically required to restart after the weekend. Electrolevels in a tube close to the tunnel crown were used to monitor the development of a longitudinal sub-surface settlement profile.