Cardiff Crossrail traffic changes begin at Callaghan Square 2026

Key Points

• Work on the Cardiff Crossrail phase 1 is set to enter the next construction phase at Callaghan Square on 17 September 2026.
• Traffic management measures will be implemented at Callaghan Square, Bute Street and West Canal Wharf from 20 September.
• The traffic management measures are expected to last for about eight months.
• These measures will provide contractors with a chance to divert a high-pressure gas main, telecommunications services and water mains under the carriageway.
• North-bound traffic will still be accessible to the Bute Street from Butetown, while access south-bound traffic from the Callaghan Square junction will not be possible.
• Those who wish to travel to Herbert Street and Tyndall Street must turn left.
• Traffic diversions will be provided through Lloyd George Avenue and Dumballs Road.
• This £100m project is being delivered by Cardiff Council and Transport for Wales, with funding from the Welsh Government and the UK Government’s Levelling Up Fund.
• GRAHAM is the principle contractor for phase 1.
• The scheme involves the construction of a new tram-train link that will connect Cardiff Central railway station with Cardiff Bay.
• Phase 1 includes a twin track tramway at Callaghan Square, a new tram platform at Cardiff Central and a further platform

Cardiff (Wales Times) September 2026 – Work to transform Callaghan Square for the first phase of uk/local/cardiff/">Cardiff Crossrail will move into its next stage on 17 September, according to a report by Inside Media. The associated temporary traffic arrangements will come into force from 20 September and will affect Callaghan Square, Bute Street and West Canal Wharf.

The changes are required to create a safe working area for major utility diversions beneath the carriageway. The works include the relocation of a high-pressure gas main, telecommunications infrastructure and water mains.

According to Mark Mansfield of Nation.Cymru, the temporary arrangements are expected to cause disruption for approximately eight months. The newspaper reported that the latest phase of construction will change how vehicles move through the area while the infrastructure is prepared for the new tram-train route.

The project team has said the utility diversions must be completed before the tram infrastructure can be installed. The work is therefore an enabling stage of the wider Cardiff Crossrail construction programme rather than the final installation of the tramway itself.

How will traffic move from 20 September?

Bute Street from Butetown will remain open to northbound traffic at its junction with Callaghan Square. However, motorists travelling towards Herbert Street and Tyndall Street will be required to turn left.

Drivers will then be able to travel west or use the Callaghan Square roundabout to continue north or east. There will be no southbound access to Bute Street from the Callaghan Square junction.

Streets south of Callaghan Square accessed from Bute Street will only be reachable from the south. Diversion routes will be available through Lloyd George Avenue and Dumballs Road.

Variable Message Signs and additional roadside signs have been installed to inform drivers about the changes. Cardiff Council is advising motorists to plan journeys in advance and use alternative routes where possible.

The changes will also affect people travelling to local businesses, residential areas and facilities around the square. Residents and businesses are being encouraged to allow additional time for journeys during the construction period.

Why are the road changes needed?

The road changes are necessary because the project involves complex work beneath the existing carriageway. Utility networks serving residents and businesses must be moved or protected before the new tramway can be built.

Cllr Dan De’Ath, Cardiff Council’s cabinet member for climate change, strategic planning and transport, said, as quoted by Inside Media and Nation.Cymru: “Cardiff Crossrail is one of the most important transport projects currently being delivered in the city and will help create a greener, more sustainable and better-connected Cardiff.”

He added that the work beneath Callaghan Square was “highly complex” because it involved diverting critical utilities serving businesses and residents across the city. Cllr De’Ath said the works were essential before the tram infrastructure could be installed.

He also acknowledged that the traffic changes would cause disruption and thanked residents, businesses and motorists for their patience while the project progressed.

The timing of the utility work means that construction activity and traffic management will continue beyond the initial eight-month period. Cardiff Council said further phases of traffic management would be required over the following two years, including additional closures on parts of Bute Street and further changes to traffic routes around Callaghan Square.

Advance notice is expected to be provided before each new phase.

What will Cardiff Crossrail deliver?

The first phase of Cardiff Crossrail is a joint project between Cardiff Council and Transport for Wales. It is backed by £100m in joint funding, with £50m provided by the UK Government and a matching £50m contribution from the Welsh Government, according to Transport for Wales.

The scheme will provide a new tram-train route between Cardiff Central railway station and Cardiff Bay. The route will cross Callaghan Square and connect with the existing Cardiff Bay line.

Transport for Wales said the project will include a new two-platform station stop in the southern car park of Cardiff Central railway station. The new stop is intended to provide interchange with existing services at Cardiff Central.

The project will also deliver a new tramway from the southern car park at Cardiff Central, through Callaghan Square, to the existing Cardiff Bay line.

A third platform is planned at Cardiff Bay railway station. Transport for Wales said this will be added alongside the second platform that is already being constructed.

The wider scheme includes improvements to public spaces along the route. These plans include new sections of segregated cycleway, improved footways and changes designed to improve connections for people walking, wheeling and cycling.

Nation.Cymru reported that a new station at Loudoun Square is already under construction. New tram platforms are also planned at Cardiff Central, while an additional platform is planned at Cardiff Bay.

How does the project fit into Cardiff’s wider transport plans?

Cardiff Crossrail is intended to form the first stage of a larger transport network. The long-term ambition is to create a route linking Plasdŵr in the north-west of Cardiff with Cardiff Parkway station in the east.

The first phase will directly connect Cardiff Central with Cardiff Bay. Further extensions would depend on future planning decisions, detailed development and additional funding.

Transport for Wales said a possible future connection could run from Cardiff Bay station to a new station at Pierhead Street. That element is subject to additional funding being secured.

The project is also aligned with the wider South Wales Metro programme. Transport for Wales said Cardiff Crossrail will build on work taking place through the transformation of the Core Valleys Lines, including improvements to the Cardiff Bay line.

The planned tram-train connection is intended to improve links between the city centre and Cardiff Bay, while supporting connections with walking, cycling and bus services.

What has been reported about construction progress?

Inside Media reported that GRAHAM is the principal contractor working on the first phase of Cardiff Crossrail. The contractor is responsible for delivering the initial stage of the scheme in partnership with Cardiff Council and Transport for Wales.

The construction programme began with enabling works in the Callaghan Square area. The next stage will focus on utility diversions and changes to the road layout.

The work is taking place before the main tram infrastructure is installed. This means residents and road users will first experience traffic-management measures connected with underground works, followed by later construction activity associated with the tramway, platforms and public-realm improvements.

WalesOnline previously reported that the first phase includes a twin-track tramway through Callaghan Square. It also reported plans for an extra platform at Cardiff Bay railway station, new pedestrian areas and dedicated cycling routes.

The project is expected to require several stages of traffic management rather than one continuous arrangement. Cardiff Council has said that motorists will receive advance notice of future closures and route changes.

How can residents and businesses receive information?

A public drop-in session is scheduled for 17 September from 4pm to 7pm at the CCHA Culture and Media Centre in Loudoun Square, Cardiff.

Residents and local businesses will be able to speak directly with representatives from the project team and GRAHAM, the principal contractor.

The meeting is intended to provide information about the next construction stage, the temporary traffic arrangements and the work being carried out beneath the road.

Motorists can also follow the roadside signs and Variable Message Signs installed around the affected area. Cardiff Council has advised drivers to check their routes before travelling and consider alternatives where practical.

What is the background to Cardiff Crossrail?

Cardiff Crossrail is a planned tram-train project designed to improve the connection between Cardiff Central railway station and Cardiff Bay. The first phase, known as phase 1a, is fully funded and focuses on the route between the city centre and Cardiff Bay.

Transport for Wales said the project developed from the wider Cardiff Crossrail vision set out in Cardiff Council’s Transport White Paper, published in July 2019.

The funded phase includes the tramway, the new Cardiff Central station stop, the connection through Callaghan Square and upgrades at Cardiff Bay railway station. It also includes changes to roads and public spaces to accommodate the tramway and improve active-travel links.

The wider Cardiff Crossrail vision would eventually extend beyond the first phase. However, parts of the broader network remain subject to future funding and approval.

The project is connected to the South Wales Metro, which aims to improve transport links across South Wales by bringing together rail, bus, walking and cycling networks.

Earlier project information indicated that construction of the main works would begin in 2026, with the first phase targeted for completion in 2028. The current construction activity at Callaghan Square is part of the work required to prepare the route for the tram-train infrastructure.

How could Cardiff Crossrail affect motorists, residents and businesses?

For motorists, the immediate effect will be longer or changed journeys around Callaghan Square, Bute Street and West Canal Wharf. The restrictions are expected to last for about eight months, while further traffic-management measures may follow during the next two years.

Residents and businesses could experience changes in access, additional traffic on diversion routes and disruption caused by construction vehicles and utility works. The council’s advance notices, roadside signs and public engagement meetings are intended to help affected people prepare.

For public-transport users, the long-term objective is a direct tram-train connection between Cardiff Central and Cardiff Bay. The completed scheme is expected to improve interchange between rail services and provide a new route through Callaghan Square.

The project may also affect people travelling by bicycle or on foot while the road layout is changed. However, the final scheme includes segregated cycleway sections, improved footways and public-space improvements along the route.

The longer-term impact will depend on construction progress, the completion of the planned stations and platforms, and the delivery of future phases.

For businesses, the construction period could create short-term access and traffic challenges. The final transport improvements may provide better connectivity between the city centre, Butetown and Cardiff Bay, but those benefits will only be realised once the relevant infrastructure is complete.

The immediate prediction is that Cardiff Crossrail will bring continued disruption around Callaghan Square as utility diversions and later construction phases proceed. Motorists, residents and businesses should expect further changes over the next two years, while the completed first phase is intended to provide a more direct rail connection between Cardiff Central and Cardiff Bay. The scale of the long-term benefit will depend on the project remaining on schedule and on future funding for wider extensions.