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agb Environmental Recommends A More Complete Ground Investigation

Always advocating a full assessment of ground conditions, agb Environmental wishes to highlight the perils of not heeding this advice after developers drilled through a tunnel wall, damaging an underground rail line.

Last March it was reported that developers unknowingly drilled through a tunnel wall of a railway line north of Old Street Station in London. A train driver noticed floodwater entering the tunnel and on further investigation it was found that two augers had broken through to block the line.

There was planning permission on the site above for a residential tower block, but the operators of the piling rig were unaware that there was an active train line below. The track was not shown on the site plan or on any map used by the developer and planning authority, meaning that Network Rail was not contacted.

The Rail Accident Investigation Board decided that the client had not appreciated the significance of an entry on the Land Registry Property Register and that the searches undertaken on their behalf prior to purchase did not include Network Rail.

This case highlights the importance of a complete and thorough exploration of ground conditions, including all maps and historical documents.

agb Environment would like to remind clients that Ordnance Survey Maps do not include railway tunnels on underground systems, which means it is key to consider Network Rail and Transport for London for development sites in the capital.

Managing Director of agb Environmental, Alex Brearley, said: “It goes without saying that this incident fortunately didn’t end in a major disaster. Understanding the ground conditions, in this case, means more than simply the soils. Our Project Management approach, and thorough awareness of Health and Safety, means we will always advise clients to ensure they undertake a thorough assessment prior to any ground works.”

To help mitigate this risk, agb Environmental routinely obtains data needed during the analysis phase to ensure any risks posed by underground tunnels are known to the client. This removes the hazard of any lengthy and costly delays to the development project once it is underway.

With experienced staff specialised in a range of sectors, including geotechnical assessments, a full assessment will be taken to include UK railways, underground lines and major transport routes, providing the necessary certification for the entire project.

More information on the incident report here can be found here.

To find out more about our geotechnical services, call us on 01638 663226.

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