Amey Case Study
Geotechnical Appraisals following Storm Events
PROJECT NAME: Walkover Surveys
NETWORK RAIL ROUTE(S): Anglia
SERVICES: Geotechnical Appraisal and risk evaluation walkovers following storm events
Our Company has supported Amey as part of the CEFA & LNW earthworks contract for the whole of CP5 across all Network Rail routes meeting the requirements of NR_L3_CIV_065 [Issue 6] 2017. Many of these earthworks border watercourses along rivers, waterways, and coastlines.
Part of the earthwork inspection picks up any defects associated with coastal and estuarine defences such as the condition of retaining walls and rock armour revetments. Where the interface between Network Rail managed infrastructure and coastal areas is via a soil slope or cliff face, this will also be examined as an earthwork asset.
The inspection also picks up on any scouring associated with the interaction between the moving water and the toe of the earthwork, where an earthwork borders a river.
Our Operations Director (formally of CEFA, Amey) in conjunction with our Managing Director were involved in a walkover survey of the NOL (Needham to Lowestoft line) in the north of the Anglia route. Following a heavy storm surge along the East Coast of Britain several areas of the Anglia Route had suffered from flooding along sections of the NOL.
Several sections of the line had suffered from washout failures and extensive flooding causing some scouring and therefore disruption to train services.
This line is part of the low-lying Norfolk Broads water system, and the area is flat and open with very little high ground. Some areas in the region have been reclaimed from the sea and are also below sea level.
Large sections of the line run alongside the River Waveney part of the Oulton Broad. Drainage ditches cross the railway via culverts at many locations, and most of the adjacent ground is marshland.
Features checked during the visual inspection included revetment walls, gabion baskets, rock armour, earthworks, natural slopes, stone pitching, kingpin walls, underbridges, culverts rock blankets and drainage channels paying particular attention to signs of scour, washout, earthflow, overtopping, cracks out of plumb as well as the structures overall condition.
The walkover survey picked up areas of concern to the safe running of the railway and in areas identified washout type features where the adjacent drainage had become overwhelmed with the amount of rainwater, surface runoff and high tides.
Extensive flooding in the adjacent salt marsh and coastal grassland was evident, and in areas the flooding had reached the trackbed causing scour features. All findings and recommendations were supplied back to our client highlighting intervention works where required.
Due to emergency nature of this work, we were able to mobilise and report back to the client swiftly so that normal services were able to resume on the line.
Inspections of this nature in the rail environment are a highly specialised skill and every one of our examiners has extensive experience in this field. We review their competency annually in accordance with ‘NR SP CTM 017 Competence & Training in Civil Engineering’. We continually monitor our examiners for quality and accuracy and provide further training and/or mentoring where required.