HSE investigating cause of incident that saw two piling drills from a north London construction site pierce a London train tunnel

The HSE is investigating the cause of an incident on a building site near Old Street, London, that saw piling drills pierce the wall of a London train tunnel on Friday.

The HSE said the incident occurred on a building site on 99 East Road, Hackney, just north of Old Street station.

According to a planning application submitted to Hackney council, the project, being developed by Protean Developments and designed by Charlotte Ambrose Architects, is a seven-storey mixed-use development, comprising commercial space at the ground floor and nine residential apartments above.

The site currently carries the signage of Andrew Towns Wadey (Builders) Ltd.

It is understood that civil engineering contractor All Foundations was carrying out the piling on the job.

A spokesman at All Foundations said: “We are not allowed to comment on this matter. It is all being handled by the main contractor.”

Andrew Towns Wadey, the owner of Andrew Towns Wadey (Builders) Ltd, declined to comment about the incident, other than to say that “everything has been handed over to the insurance company”.

The incident, which occurred on Friday morning, saw a train driver forced to take evasive action when two large piling drills came through the tunnel wall of the Moorgate to Finsbury Park Northern City Line.

The incident lead to the closure of the line, but Network Rail said on Monday that services were up and running again after engineers had worked over the weekend to repair the damage.

Network Rail said the tunnel was a former London Underground tunnel, with the bore constructed of a cast iron top with a lower portion made of brick.

The hole in the cast iron was covered with a steel plate, with a one tonne concrete plug then poured to seal the hole, which made it watertight and safe to run trains, Network rail said.

A track circuit failure caused by standing water meant some delays to services on Monday morning but it has since been cleared.

Network Rail said engineers would be working every night this week to pump out the remaining water and replace the ballast that supports the tracks that had been damaged, with work will continuing in the weekend to backfill the hole left by the drills using pulverised fuel ash grout.