Details revealed of 'mammoth' Cardiff tramway project

Emily Price 

Further details have emerged of a "mammoth" new tramway in Cardiff which is expected to close a critical gap in the Welsh capital’s connectivity.

The collaborative Crossrail scheme will see Cardiff Council and Transport for Wales (TfW) work together to deliver a tramway from Cardiff Central railway station to Cardiff Bay, connecting the two directly by rail for the first time.

The long awaited tram line has been hit with years of delays and uncertainty due to a lengthy Welsh Government review after the initial planning permission was granted in April 2022.

A November news article published by New Civil Engineer has revealed further details of how Cardiff's new transit system will be delivered.

It explains that the £100m, 800m long Phase 1a of Cardiff Crossrail will create the foundation for the light rail system.

Cardiff Council director of planning, transport and environment Andrew Gregory told New Civil Engineer: "In terms of Phase 1a, that forms the catalyst to create an east-west link, but it also has a focus on providing the spinal connection of a big development corridor from Cardiff city centre to Cardiff Bay."

The tramway will start with a dedicated stop at Cardiff Central Station, then will travel through Cardiff's Callaghan Square and connect to the existing Cardiff Bay railway line.

The southern arc of Wales' capital is one of the most deprived areas of the country.

It's hoped that by connecting deprived communities with the city centre the project can boost jobs and growth in the area.

The tramway will also link with plans for a new 16,500-capacity indoor arena in Atlantic Wharf in Cardiff Bay set to open in 2028.

Andrew Gregory added: "Between the new arena being built in Cardiff Bay and Cardiff Central Station, there are further development works going on in the city.

"Phase 1a will form the sustainable transport spine of that development corridor. Crossrail is the first step in achieving the sustainable transport vision for the city."

TfW and Cardiff Council worked together to go to both the UK and Welsh Government's to make the case for the multi-million pound rail project.

Metro

The Welsh Government has provided funding of £50m and the UK Government had provided £50m through the Levelling Up Fund.

The new Crossrail line will also aim to link up with the newly revamped Core Valley Lines network.

TfW is currently in the process of electrifying around 170km of track as well as upgrading stations and signalling as part of the South Wales Metro project.

Earlier this year TfW began testing brand-new electric tram-trains on the recently electrified Valleys railway lines.

Meanwhile, Phase 1b of the Cardiff Crossrail project is still at concept stage.

This phase will see an extension through Cardiff Bay to the Pierhead building with the refurbishment of Cardiff Central Station planned as a separate project.

WSP was appointed in early 2024 to provide programme and management services, working alongside cost consultant Rider Levett Bucknall.

Construction engineering company Graham Group secured the contract to design and build Phase 1a of the tramway in 2024.

Engineering company Amey was appointed as a design partner and will be responsible for highways, drainage and public spaces.

Highway and public realm works are expected to begin next spring while construction of the tram track and platforms at Cardiff Central Station will take place in late 2026.

Challenge

It's hoped that Cardiff's new tram link will become fully operational by mid-2028.

Conceptualising the project has proved challenging because it involves multiple interconnected infrastructure projects as well as the integration of new routes with older infrastructure.

Cardiff Council's operational manager for major projects Gethin Shields told New Civil Engineer that collaboration has been key due to the large number of documentation required across several parties.

For example, a key piece of documentation is the TWA (Transport and Works Act).

The legislation relating to England and Wales is used to authorise major transport schemes.

Sheilds said that over the summer, over 50 documents, drawings and reports were submitted to the Welsh Government.

He said: "It goes through all the transport assessments, planning documentation, heritage impact assessments, drainage, all those things that you would normally have to do for the project.

"Documentation has been one of the challenges, but it’s been overcome through the strong relationships and collaboration that the council and TfW have had working together."

The Cardiff Crossrail scheme will also involve improvements to the city's active travel routes with new walking, wheeling and cycling links and improved footways for pedestrians.

This will involve changes to the road layout on Callaghan Square and traffic routing in the area.

Design

Sheilds told New Civil Engineer: "One of the biggest challenges we had was during the concept design stage, where we were coming up with an arrangement for the Callaghan  highway and tramway that worked for everybody.

"We were working towards an optimal solution that wouldn’t cause massive congestion."

Using automatic number place recognition cameras to collate data, a traffic model has been created using traffic simulation software.

This has allowed the scheme's collaborators to create a working model of the existing situation at the site today and can add all the known developments that are going to be in play for when the tramway goes live.

Further design challenges for Phase 1a will include the removal of two roundabouts at Callaghan Square and reduction of three lanes of traffic both sides of the gyratory system to one lane in each direction.

Filter lanes will also be added to make space for the tram line.

Cardiff's historic canals have had an impact on the scheme's design with collaborators required to identify the ground conditions where the tramway intersects with the city's waterways.

Graham contracts director Andrew Henry told New Civil Engineer: "There are also Victorian sewers and quite a lot of services, such as tower services in a fragile condition or unknown condition.

"Where the scheme ties into the CVL in the Bute Street area, there’s an existing masonry retaining wall.

"However, that existing wall appears to have no foundations. So again, there are a few geotechnical challenges in development design.

"Additionally, we’re incorporating the track into the existing highway, so there’s only so much we can deviate from the existing highway level in terms of the track.

"To limit that, we’ll have to try and work the track as close to road level as possible.

"We’re looking at altering the track design so that we can reinforce the track at various points, which would allow us to get away with a slightly slimmer track substructure design to pass over the services."

Utilities

Engineers are also building 3D models of the underneath of the utilities in the area and running a clash detection process to design the project around utilities.

Henry added: "That’s about creating a model in which all the elements tie in with each other, to make sure that involved parties are getting that model with the clash detection built in.

"That means we can all identify where there may be a service clash that would affect not just the track, but the support infrastructure for the track, including drainage, signal cables, power cables and so on."

Collaborators of the Cardiff Crossrail scheme say they have drawn on learning from schemes such as the Edinburgh Tram Network - an 11.5 mile line which runs between Newhaven and Edinburgh.

During its constriction the Scottish project used reinforced soil structures, non-load-bearing bridge abutments and the construction of retaining walls and bridges, as well as a portion of the concrete track line.