Transport for Wales Taff’s Well Depot - ambitious design at the heart of the South Wales Metro

An Arial view of a construction site.
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Amey took on the ambitious task of designing the depot at the heart of the new South Wales Metro

Transport for Wales (TfW) awarded the 15-year franchise to operate train services in the Wales and Borders area to KeolisAmey. The agreement included the development of the South Wales Metro – an integrated public transport network for the Cardiff and valleys area. A key element of this project was the introduction of a fleet of light rail vehicles (LRVs), to be housed at a new purpose-built depot at Taff’s Well.

The new depot would play a critical role in the transformation of the rail service in the region. It would not only provide stabling and maintenance for the new tram-trains, it would act as an operations base for TfW and host a signalling control centre for the part of the network known as the Core Valley Lines (CVL).

Amey's Transport Infrastructure business, the principal contractor, appointed Amey Consulting to produce detailed designs of key elements of the facility, including the track, signalling, telecoms and electrical power infrastructure, plus overhead line equipment (OLE) for the stabling area. Other packages of work were assigned to contractors including Arcadis (the maintenance shed, office building and civil engineering works), NG Bailey (mechanical and electrical design), and Alun Griffiths (the depot building and other elements).  

The depot was to be constructed on derelict industrial land adjacent to Taff’s Well station. It would have one connections to the main line to the north with a turnback requirement at Taffs station to head towards the South. Facilities would include overnight stabling for 34 three-car tram-train sets, a shed for heavy maintenance, sanding facility, a ‘wash road’ for cleaning, a wheel lathe road within the maintenance shed and an area for underframe cleaning. Also includes offices and a simulator room for the end users.

An Integrated Control Centre (ICC) would be built at the northern end to house the signalling and electrical control rooms for the CVL. Signalling for the depot, managed by a bespoke depot control system (DCS), would operate from a dedicated workstation within the ICC building.

The project presented several challenges. Fitting all the necessary infrastructure into a tightly constrained space was one, as was transferring control of the CVL signalling to the ICC. Handling complex train movements within the depot, as well as to and from the main line, required an innovative control solution.

Close management and integration of many contractors/disciplines is a necessity. This was done using a range of CAD platforms and modelling tools. The situation was exacerbated by uncertainty over the client’s operational requirements, resulting in an ever-changing scope of works.

To facilitate integration and collaboration, Amey Consulting introduced a structured design management process. This was based around the development of a federated model known as the PIM (project integrated model), providing a clear view of everyone’s designs. Two-weekly interdisciplinary design checks (IDCs), along with a clash detection system, ensured the various discipline designs interfaced properly.

Regular design review meetings and workshops were held with Amey Rail and other stakeholders to monitor progress and ensure the client’s requirements were being met. The creation of a 3D video ‘fly-through’, based on the PIM, helped stakeholders to visualise the operation of the finished depot.

Another example is the innovative use of technology for the depot control system. Determining that traditional signalling control methods were inadequate for the task, Amey developed an approach based on PLC (programmable logic control) interlocking technology. The system is COTS (commercial off the shelf) based, meaning it can be accessed, modified and upgraded by other contractors – with obvious benefits to the depot operator.

Amey Consulting's contribution has earned the praise of stakeholders and clients alike. Commenting on the 3D video presentation, the AmeyKeolis design director for Wales and Borders said: ‘Being able to feel how a Metro vehicle will enter Taff’s Well Depot, how the batteries will be charged and virtually walk around the facilities, shows what this great team is delivering every day.’ TfW’s rail programme director added: ‘A hugely motivated joint team, delivering a huge benefit to the people of Wales. Well done team.’

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