Raymond Brown’s Rail Team has significant experience of tunnel maintenance and repair and strengthening in the rail environment.
Raymond Brown has extensive experience in carrying out a wide range of tunnel and subway maintenance schemes including embankment stabilisation, masonry repairs and restoration, lighting, ventilation and drainage systems.
Napier Road Underpass
Client: Reading Borough Council
Napier Road Underpass, in Reading, aims to link two areas of Reading for pedestrians and cyclists. Previously the route was via very busy roads. The existing tunnel was originally part of a link to the Huntley and Palmer biscuit factory and the Great Western Railway, which has been unused for many years and had had part of its south side arches removed.
The works for the formation of Napier Road Pedestrian and Cycle Underpass through an existing disused rail tunnel included: Forming the construction compound and access ways for the works; Erection of security fencing to Network Rail specifications; Installation of a new canopy to the south entrance and rain water collection; Installation of the footpaths and surface finishes; Formation of the north and south footpath interfaces; Signage and lighting installations.
The project team were faced with a challenge of managing and delivering the works in a busy public environment with other projects being delivered simultaneously by third parties within the vicinity including: Construction of the new Reading pedestrian and cycle bridge over the River Thames; Reading Bridge strengthening works; Network Rail’s Reading Station area redevelopment works.
There were multiple stakeholder interfaces throughout the duration of the project with safety and security being the key components in ensuring the effective continued operation of the commercial and public spaces affected by the works.
Fareham Tunnel Brickwork Repairs
The brickwork repairs to the tunnel lining at Fareham forms part of Network Rail’s CP5 Wessex Programme to improve the Tunnel Condition Marking Index (TCMI) score for 26 tunnels.
The CP5 Regulatory target is for TCMI scores to be greater than 82.9 in the Wessex area. Fareham No2 tunnel has a current TCMI score of 76.5 and consequently had been identified as a high priority site.
In the case of Fareham No2, the TCMI rating will be improved by undertaking a combination of treatment works consisting of: Replacement of defective/spalled brickwork with new to sidewalls; Re-pointing open joints with designated mortar; Replacing missing bricks.
The works will in the main follow Network Rail’s Standard Design Details for tunnel maintenance, and shall be carried out with track protection.
The challenges encountered on site to date have been restricted access and working in very wet conditions. To overcome the running water behind the spalled masonry, we installed a series of weep-holes to channel water to the face, and using a quick set waterproofing additive in the mortar.
Tapnage Tunnel Brickwork Repairs
The brickwork repairs to the tunnel lining at Tapnage forms part of Network Rail’s CP5 Wessex Programme to improve the Tunnel Condition Marking Index (TCMI) score for 26 tunnels.
The CP5 Regulatory target is for TCMI scores to be greater than 82.9 in the Wessex area. Tapnage tunnel has a current TCMI score of 72.2 and consequently has been identified as a high priority site.
In the case of Tapnage, the TCMI rating was improved by undertaking a combination of treatment works consisting of: Replacement of defective/spalled brickwork to side walls, haunch and then crown; Repointing open joints with proprietary mortar; Removal of vegetation and ivy on and within 3m of the structure; Scraping and jet cleaning of calcite, soot and algae growth areas; Stitching and re-pointing of fractures.
The works, in the main followed Network Rail’s Standard Design Details for tunnel maintenance and was carried out with track protection.
We were faced with many challenges on the scheme which were successfully overcome including Hand Arm Vibration Syndrome (HAVS) involved with the breaking out operation. To mitigate this risk, we introduced specialist plant which significantly reduced the risks associated with HAVS.
The installation of Vortok fencing also enabled us to work full shifts which would have otherwise been restricted to possessions at night.
Alfreton Old Tunnel
Client: Network Rail
Significant investment has been made in developing Raymond Brown’s tunnel maintenance and repair capability including undertaking a trial installation of a RAM Arch support system in a disused rail tunnel at Alfreton, Derbyshire. This trial was successfully completed under ‘possession’ conditions.
The installation of 75 linear metres of RAM Arch to the soffit of Grimstone Tunnel, near Dorchester.
Grimstone Tunnel is constructed from brickwork that over the years has deteriorated and is now showing signs of spalling. The RAM Arch system being installed is designed to prevent loose bricks falling and reduce the risk of the potential for a serious incident at Grimstone Tunnel.
The works were undertaken during possessions of the line using rail mounted plant.
Client: Dorset County Council
Raymond Brown Construction were approached to carry out the slope stabilisation and other works on the tunnel partial collapse of Beaminster Tunnel as part of the five year Dorset County Council framework.
The works involved site clearance and over 850 soil nails which were driven into the slope and connected and tensioned to a TECCO mesh that covers and retains the surface layers. An erosion mat sits under the mesh to prevent soil washing away. Extensive drainage works were also undertaken to remove water from the soil nailed slopes and prevent surface water from adjacent ground running onto the stabilised area. At both the north and south portals, the end few metres of the arch were strengthened and waterproofed with reinforced concrete retaining walls. The wing walls on the approach to the tunnel were anchored into the slopes with soil nails drilled through the wall into the ground behind.