Key Points

• Significant train delays are expected in Cardiff and the wider Wales rail network this weekend because of planned engineering work.
• Transport for Wales says all lines through Cardiff Queen Street will be closed from Sunday, May 24, to bank holiday Monday, May 25.
• Rail replacement buses will run on several routes to keep passengers moving during the disruption.
• Services from Treherbert and Merthyr Tydfil will divert via the City Line, while some routes will terminate at Cardiff Central.
• Tickets will be accepted on selected Cardiff Bus routes at no extra cost, including routes 21, 23, 27, 6, 92, 93 and 94 on certain sections.
• Passengers using the Cardiff Bay Line and other affected routes are being urged to allow extra time and plan journeys in advance.

Cardiff (Cardiff Daily) May 22, 2026 – Significant train delays are expected across parts of Cardiff and the wider valleys network this weekend as planned rail improvement work closes key lines and forces changes to train services and replacement bus routes.

What is being closed?

As reported by Transport for Wales, planned infrastructure improvements will close all lines through Cardiff Queen Street between Sunday, May 24, and bank holiday Monday, May 25.

The closure will affect a number of routes across the Cardiff and valleys network, with services disrupted on lines serving Rhymney, Caerphilly, Radyr, Cardiff Bay and other parts of the city. Transport for Wales says passengers should expect major alterations and allow extra time for their journeys.

Which services will be diverted?

Transport for Wales says services from Treherbert and Merthyr Tydfil will divert via the City Line through Fairwater.

The operator also states that trains from Penarth to Coryton will terminate at Cardiff Central. In addition, buses will replace trains between Radyr and Cardiff Central, while some services will run between Cardiff Bay and Radyr with bus connections at key stops.

What replacement travel is available?

According to Transport for Wales, rail replacement buses will operate across several affected corridors to keep passengers moving during the blockade.

The company also says tickets will be accepted on Cardiff Bus routes 21, 23 and 27 at no extra cost, as well as on routes 92, 93 and 94 between Penarth and Cardiff city centre, and on route 6 for the Cardiff Bay Line. An additional hourly bus will run between Radyr and Cardiff Bay, calling at Llandaf, Cathays and Cardiff Queen Street.

How will this affect passengers?

Passengers on the affected routes will need to leave more time for travel because replacement buses and diversions are likely to take longer than normal train services. Journeys across the Cardiff and valleys network may also require changes at Cardiff Central, Radyr or other interchange points depending on the route.

Transport for Wales says the changes are part of essential improvements rather than emergency repairs, which means the disruption is planned but still likely to be widespread.

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What has Transport for Wales said?

Transport for Wales says the work is needed as part of wider rail improvement plans across the network. The operator says the closures are intended to improve journeys in the longer term, while short-term measures such as bus replacements and diversions are being used to keep passengers moving during the works. National Rail also lists the disruption as planned engineering work affecting Cardiff Central and several valley lines.

Background of this development

Planned rail engineering work is a regular part of maintaining the South Wales network, particularly on busy corridors into Cardiff.

Network Rail has previously said similar works involve track renewals and station-area engineering to improve reliability and journey times. In this case, the closure through Cardiff Queen Street sits within a wider pattern of maintenance and upgrade work that often requires temporary service reductions, bus replacements and route diversions.

Prediction for passengers

For daily commuters, weekend shoppers and travellers heading into Cardiff, the most immediate effect will be longer and less direct journeys. People travelling from the valleys into the city centre may face the biggest changes, especially where services divert via the City Line or terminate early. If passengers follow the replacement travel advice and check altered timetables before leaving, the disruption should be manageable, but delays and crowding on buses are still likely throughout the closure period.