Melgarve substation is a 132kv/400kv Substation in the Scottish highlands, currently part of the SSE framework of works being undertaken by Siemens Bam. The site team, most of which worked at Loch Buidhe Substation, identified the potential benefits of 3D modelling for clash detection and therefore developed a detailed model of the underground services within the substation.

The design information is primarily in the form of traditional 2D PDF drawings. To complicate matters, various elements of the substation (foundations, ducting, cable troughs, roads, earthing etc.) are designed by several different design organisations. Whilst every effort is made to ensure that the designer’s individual elements work together, there are inevitably clashes. Particularly, when changes are introduced.

To reduce rework and identify clashes before work commences the 2D drawings were developed into 3D models which were then combined into a single 3D coordination model. This allowed the components fit to be verified in advance of the site operations.

When issues were identified the site team recorded them and issued RFI’s to the designer in order to resolve the clashes without rework or delays on site.

The model has been developed with members of the site team modelling individual elements. The various elements are then combined and uploaded onto BIM 360 Field to form the federated model. The modelling is carried out using AutoCAD with Navisworks and 360 Glue used to upload the model to BIM 360 Field. All of these tools are available at no extra cost to the project.

One element of substation construction which, from an outside perspective may seem to be a very simplistic construction element is the ducting. However, the sheer volume of ducting and the complexities of the ducting routes combined with added obstacles of drainage, foundations and earth tape makes the routing of the ducting around the site a difficult task.

Some examples of areas which benefited from the 3D modelling are shown below. This model can also be viewed on site using BIM 360 Field and is a helpful tool in understanding the complicated layering of the services.

Colour coding the model aided identification of different materials and elements of the substation. For example general purpose ducting is shown in red, HV ducting is in yellow, Surface water drainage is in blue etc.

The cable trough design has been modelled using the precast unit design developed at Loch Buidhe, this saved time in the design and procurement stage and minimised additional work such as in situ sections or cutting/coring of troughs. The various types of trough are modelled in different colours to simplify the installation process and ensure that the correct unit types are used.

More recently the team trialled the use of the Google Cardboard VR headsets. Three dimensional images with perspective were created by processing Navisworks viewpoints of the model into images compatible with stereoscopic VR. This was a relatively simple process, done through Navisworks and uploaded onto Autodesk 360. The images can be shared through a public link and viewed on any smartphone.

The site team believe that it provides some real benefits as it does not require any additional software to view these on a smartphone and they can be easily shared through QR codes placed on site or by emailing a link to the workforce. They can also be used to aid inductions, activity plan briefings or toolbox talks.

“It is really impressive to see how the site team have taken it upon themselves to coordinate and communicate the design in this way. It will be interesting to see how these benefits multiply when the designs are provided as standard in this 3D format and the coordination carried out by the consultants themselves.” David Milnes, Digital Construction Manager.