And the Winner is… Collett & Sons Ltd


Collett & Sons Ltd Win The Heavies Team of the Year Award

In the Judges words: ‘The winner’s planning, engineering, installation and heavy transport teams combined as one to carry out this impressive trio of heavy transformer moves within a tight framework – top-quality work as ever.’

As part of a substation upgrade programme, Collett were appointed to deliver three super grid transformers to UK National Grid substations in a four week period. With six months from the awarded contract to the required delivery, this provided a tight timescale in which to plan and execute the project.

Collett Named as the Heavies Team of the Year

Each project involved Collett’s Projects & Heavy Lift Teams to undertake all the pre-planning works, the discharging of each super grid transformer from its originating vessel at the dedicated port, delivery of the transformers and final jacking & skidding operations. Except in the case of Willenhall which also required a TTRO (Temporary Traffic Regulation Order) of a residential road to allow for SPMT operations due to site access restrictions.

Each of the loaded 66m long combinations required end-change procedures at select parts of the route to allow for transportation. This involved uncoupling each of the heavy tractor units, positioned in a push-pullonward configuration, and recoupling in a mirrored formation, flipping the combination 180 degrees. Across all three transportation projects, this manoeuvre had to be undertaken on numerous occasions to facilitate access to the substation sites.

Working to a 2, 1 and 2 day schedule respectively, each of the transformers travelled the intricately planned routes.

In the case of Cellarhead this required the transformer to be positioned above the awaiting skidway before hydraulically lowering on to the track. Once in place the side beams of the girder bridge were disconnected and equipped with their support wheels allowing the front and rear bogies to be autonomously driven clear of the transformer. This allowed Collett to hydraulically jack & skid the super grid transformer across the 23m track to its resting plinth.

Following a similar procedure to Cellarhead, the transformer destined for Lovedean was securely positioned on the awaiting skidway, however, due to site restrictions this necessitated a more innovative solution to position the cargo. Faced with these restrictions the Collett Team engineered and implemented a multi-directional system to skid the super grid transformer over a bund wall on to a steel platform. Once situated on this platform the hydraulic system was then repositioned at a 90 degree angle allowing their Teams to complete the positioning.

Collett Awarded the Heavies Team of the Year

In the case of Willenhall this was a much more complex operation as the girder bridge would not be able to access the substation grounds. With a Temporary Traffic Regulation Order in place outside the substation Collett Teams began transhipment operations to discharge the transformer from the girder bridge to a 6-axle SPMT with an adapted operating speed to suit the axle loads. Once loaded, the SPMT was hydraulically lowered, reducing the loaded height of the transformer to 5.6m and allowing the cargo to be driven on to site and lowered to support stools to await jacking & skidding operations.

Throughout the extensive planning of all three projects Collett’s Engineering Teams implemented detailed jacking & skidding stress and pressure simulations to analyse the skid track behaviour and stress distribution across the system throughout the movement. Replicating the movement of the transformer across the 400 Tonne capacity system allowed us to calculate ground pressures, stresses and deformations across the track.

In a four week period Collett travelled 270KM with a total of 507 Tonnes. With the media having been notified ahead of each movement to minimise disruption, each project was undertaken in the presence of onlookers. Combining intricate planning, innovative engineering, expert heavy haulage and specifically engineered jacking & skidding operations, Collett completed this hat-trick of super grid transformers!