Project outline

Watford cutting is located on the northern part of the Watford Tunnel. We were contracted by Network Rail to carry out remedial works, to prevent deteriorating cutting chalk from affecting passing trains.  

The scope of works included:

• The removal of approx.14,600m² of vegetation up and down fast cuttings
• Scaling of chalk face on the up and down fast lines
• Installation of 650 active anchors
• Installation of 440 passive anchors
• Installation of approx. 4,000m² of Enkamat
• Installation of 9100m² of passive meshing
• Installation of 6100m² of active meshing
• Installation of a temporary catch fence and temporary crest access systems for drilling operations

Key challenges

• There was limited access around the site, as it was located in between the Watford fast and slow lines. This presented a challenge when delivering plant and materials to site.
• The cutting had very steep slopes, so we employed Industrial Rope Access Trade Association (IRATA) operatives for the works, who had the expertise and training to safely work on high and on steep cuttings.
• The site is situated on the West Coast Main Line and has live overhead lines. This limited the amount of soil nails that could be installed during the day, as operatives could not be less than 75 meters away from live overhead line equipment.
• We designed a bespoke catch fence, to protect the railway from falling materials, while vegetation was being removed and the soil nails were being installed. This allowed operatives to work during the day while trains were still running.
• Due to the close proximity of the slow lines to the fast lines and to any line open (ALO) working requirements, rail road vehicle (RRV) access was limited. To overcome this, the site team installed the catch fence in small sections. This allowed a drilling rig to be winched down onto the cutting, which meant we could install soil nails during full possession and isolation.

Project delivery and innovations

• To complete the project in a timely manner, we carried out an Outside Rules Of Route (OROR) possession of the fast lines. In close co-operation with our plant team, we installed the specialist drilling rigs onto the RRVs. This meant the drilling rigs could be tested prior to the possession/blockade. Due to this method, we were able to install 301 soil nails during the blockade, rather than the 220 soil nails originally planned, and therefore we were able to reduce the project programme.  
• We designed a bespoke temporary catch fence and winch system for the drilling rigs, which meant we could install the soil nails during the day.
• We used Geobind soil for the temporary haul road, which reduced the number of vehicles delivering stones to site and therefore reduced the amount of carbon emissions produced.

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