Voided Structure, River Nene Viaduct
Overview
The project required intrusive investigation as part of Network Rail’s Hidden Critical Elements (HCE) Review by means of core drilling holes in the abutments, piers and spandrels to confirm or otherwise the presence of hollow or voided elements of the structure by using CCTV cameras and endoscopes.
Key Challenges
Due to the close proximity of the works to the River Nene EWCE consulted with the Environment Agency and Northamptonshire County Council to ensure the required consents were in place before work commenced on site. An ecology survey was also undertaken to establish whether there were any issues that may affect the proposed works, in particular the presence of bats and nesting birds in the holes, cracks and crevices and the watercourse was searched for evidence of newts, water voles and otters. Appropriate segregation was implemented to exclude the work areas from pedestrians and cyclists.
Due to the potential risk of Hand Arm Vibration (HAVs) to the drillers, EWCE’s method to complete the works was for the drillers to use a combination of low vibration hand held core drills and drill rigs, monitored by the Site Manager to ensure that the maximum trigger levels were not exceeded to reduce the risk of Hand Arm Vibration (HAVs).
Added Value
Small diameter holes were cored and endoscopes used to ascertain HCE elements first thus limiting the number of larger more destructive core holes required for CCTV operations.
A combination of tower scaffolds, 4×4 vehicles and environmentally friendly plant and welfare facilities were used to minimise the impact to the local environment.