Civil engineering firm Kier has been fined more than £4.4m after a digger used to load a truck hit overhead powerlines which landed on the M6 in the path of passing vehicles.

An HSE investigation also found that in another incident a lorry was hit by an overhead cable brought down by the Kier workers.

The investigation also discovered that Kier workers had failed to tell the network provider Scottish Power about one of the two incidents.

Both incidents happened on overnight road works part of the smart motorway scheme between junctions 16 and 18 near Sandbach in Cheshire.

During the first incident, a team of three Kier workers were clearing tarmac from the hard shoulder onto a truck using a digger during a nightshift on 28 March 2018.

As the driver moved the digger along with the attached loading bucket raised, it struck and severed a 11kV overhead powerline that landed in the motorway and in a nearby field.

The company failed to immediately tell Scottish Power, which meant the cable was reenergised a number of times while it was lying on the motorway and vehicles were passing.

During the second incident, another team of three workers from a sub-contractor were removing a temporary motorway barrier on 21 January 2019.

The crane arm that was attached to their lorry loader struck an overhead cable which led to an unmarked 11kV powerline being hit and snapped by an oncoming lorry.

HSE found that inadequate planning from Kier meant the vehicle used in the first incident was unsuitable despite other more suitable vehicles being available.

There was also no task-specific risk assessment available for the workers.

In the second incident, the workers said that they were unaware of the overhead hazards.

In relation to the first incident, Kier Infrastructure and Overseas Limited, of Clippers Quay, Salford pleaded guilty to breaching Sections 2(1) and 3(1) of the Health and Safety at Work Act 1974.

In relation to the second incident, they pleaded guilty to breaching Section 3(1) of the Health and Safety at Work etc. Act 1974 and Regulation 13(1) of the Construction (Design and Management) Regulations 2015.

In total, the company were fined £4.415m and ordered to pay costs of £87,759.60 at Manchester Crown Court on 12 January 2023.

HSE inspector Mike Lisle said: “This is a significant fine reflecting the seriousness of the failures here. The company’s failure to plan the work properly and provide an adequate risk assessment put its workers and those using the motorway in significant danger.”