Project Description

Introduction

Project Name: Ardley Tunnel North Drainage
Customer Organisation: J. Murphy & Sons LTD.
Customer Details: Mr Stuart Williams, Project Manager
Value: £280,000

Schedule of Works

The contractor was commissioned to carry out drainage renewal works on the NAJ3 between 15m 1480yds and 15m 1640yds, as a result of frequent flooding, which was reportedly originating from the 6 foot drainage at the mouth of Ardley Tunnel. There was evidence of damage and calcite build-up in the existing system. The failing drainage was negatively affecting the track quality in the area, with the imposition of a speed restriction becoming likely.

Critical Construction Details Adhered To

  • Drainage systems manual – NR/L2/CIV/001 – 015
  • Drainage system track and off track – NR/CIV/SD/350
  • Track and structure movement NR/L2/CIV/177
  • Manage critical rail temperature in accordance with NR/L2/TRK/001/mod14
  • Works were checked and documented by competent and experienced track handback engineers in accordance with NR/L3/TRK/1016 and NR/L2/TRK/001/mod13
  • Carry out stressing of rails in accordance with NR/L2/TRK/3011
  • Carry out as-built survey to confirm installation was compliant with NR/L2/TRK/2102
  • Technical Approval in the Design of Track Infrastructure – NR/L2/TRK/2500
  • Management of tight clearances and track position – NR/L2/TRK/3201
  • Permanent Way Standard drawings (RE/PW series) NR/L2/TRK/7004
  • Track Design Handbook – NR/L2/TRK/2049
  • Design and Construction of Undertrack Crossings – NR/SP/CIV/044
  • Wood Sleepers, Bearers and Longitudinal Timbers – NR/SP/TRK/029
  • Management of Gauging and Clearances – NR/SP/TRK/036
  • Engineering assurance to track project – NR/L2/TRK/2500
  • Engineering assurance for building and civil engineering works

Challenges

  • Severe time constraints due to only having 4 hours midweek on rules of the route with the access point being a mile and half away
  • Robust strategic planning with plant and building an onsite lay down area
  • Heavy flow of water from the tunnel mouth drainage
  • Bungs and large over-pumps redirecting the majority of flow past the works and straight into the outfall ditch
  • Running of drainage system through existing structures (bridges)
  • Re routing drainage around structure and footings to achieve fall and flow ration required

Risk Reduction Measures

  • Mobilise on site and prepare suitable compound and working area
  • Track and structures were monitored before, during and after works to  detect any movement introduced by civil engineering works
  • Reducing excavation lengths to avoid destabilising the track or cutting slope
  • Establishing the position of structural elements prior to excavation to  mitigate against damage to bridge abutments when installing drainage  through overbridges
  • Safe manual handling was achieved by identifying the weights of items at  the planning stage and procuring adequate plant.
  • S&T cables were identified and protected prior to works to prevent damage.

Summary

The scheme had many challenges but the “can do” attitude of the GBR staff working closely with our client resulted in the safe delivery of the works and as such GBR were able to deliver the completed worked ahead of the initial programme.