With the national focus on cutting carbon emissions, a new and more efficient substation was commissioned at Littlebrook Power Station, with Balfour Beatty utilising a digital and constructible workflow to deliver the works.
Littlebrook Power Station in Kent forms a critical part of National Grid’s transformation of the National Transmission Network. The original substation (responsible for reducing electricity voltage so that it’s easier and safer to deliver to homes and businesses) built in the late 1970s was heavily reliant on the harmful greenhouse gas, Sulphur Hexaflouride. As a result, it was no longer compliant with National Grid’s new low emissions targets and so a new modern substation was commissioned, one that uses the next generation of ‘gas insulating’ technology.
Balfour Beatty was contracted to design, supply and construct the new 400kV substation at Littlebrook, responsible for modelling the steel portal frame building and cladding.
Trimble’s Tekla Structures proved valuable on the project, contributing to the delivery of the works both on time and within budget. An example of this was the ability to model both the portal frame and cladding all in the same digital environment, allowing Balfour Beatty’s project team to perform clash detection and identify any potential issues, before they reached the construction stage.
The macros in Tekla Structures were also very useful, saving valuable time. The project team was able to model one eaves connection and then copy this same connection across the whole portal frame. As well as speeding up the detailing process, this automation also helped to ensure high levels of accuracy. Quick, easy and efficient, it provides users with the assurance that all fabrication data is there, as required.
Balfour Beatty encountered various obstacles during the project, one of which was the planning permission for the building and the maximum height allowed. As a result, they had to be very specific in terms of what crane was installed inside the building to ensure it had enough clearance on the roof height.
The Balfour Beatty project team worked very closely with the crane fabricator, with the fabricator supplying an IFC file of the crane, which Balfour Beatty was then able to import into Tekla Structures. Using this data, they were able to design the connecting structural steel frame around the crane, including detailing the crane rails that ran from one end of the building to the other, and checking that this and the crane itself didn’t interfere or clash with the shallow depth roof.
Trimble’s open approach to BIM and the use of IFC files also proved useful when it came to considering the Gas Insulated Busbar (GIB) – the unit that formed the centre of the new substation. The GIB was very large, taking up around three quarters of the floor space. As well as the whole portal frame having to be designed around the GIB, it was vital that the location of existing gas pipes and services were also considered.
Here, the GIB fabricator provided Balfour Beatty with an IFC file, from which the team took the surface edge information and imported this data into the Tekla model. This meant that they were able to confirm that neither the GIB nor existing services would clash with any of the new structural steelwork.
In addition to the visualisation and clash detection enabled by the Tekla model, Balfour Beatty also used Trimble SiteVison for added peace of mind on the project. Using a tablet to access Trimble SiteVison on site, the team could view the 3D model on screen with geolocation enabled, comparing and cross-referencing the model to the as-built structure. This enabled the teams to verify and confirm that the construction stage was proceeding correctly.