Long term changes are coming to Castle Street, with work set to begin to make the temporary road layout and cycleway permanent. Following site surveys and the removal of traffic islands on Kingsway, the project will move into its main construction phase towards the end of February.
Initial preparation work will start on 2 February, focusing on surveys and setting up the site. The main phases of construction are scheduled to begin on 23 February and are expected to take around 52 weeks to complete. Cardiff Council has appointed Knights Brown to deliver the scheme.
Throughout most of the works, Castle Street and the existing pop up cycleway will remain open to traffic in both directions. Closures are only expected during resurfacing works, and advance notice will be given if any are required. The current number of traffic lanes on Castle Street will remain the same, with no reduction planned.
Following detailed assessments, the council has confirmed that Castle Street needs to stay open to traffic to avoid wider disruption across the city. Closing the route would have a knock on effect on bus journey times around the Cardiff Bus Interchange, increase pressure on Central Link and the Eastern Bay Link Road while Hemingway Road remains closed, and add strain to areas such as the Butetown Tunnels and Gabalfa Roundabout, which already operate at capacity during peak hours. Planned future projects like Cardiff Crossrail also mean there is no spare capacity to absorb displaced traffic.
The permanent scheme includes a number of upgrades designed to improve safety, accessibility and air quality. These include a fully segregated cycleway built to Active Travel standards, resurfacing of the carriageway, upgraded footways and paved areas, and changes to bus stop layouts on Kingsway and North Road. Additional measures include enhanced bus infrastructure, green roof bus shelters, extra landscaping and traffic management changes aimed at improving air quality.
Castle Street has been a focus for air quality improvements for several years. In 2018, pollution levels on the street breached legal limits for Nitrogen Dioxide, prompting Welsh Government to direct Cardiff Council to develop a Clean Air Plan. A temporary road layout was introduced, reducing traffic lanes from three to two, retaining the westbound bus lane and installing a two way cycleway.
Since those changes were made, Nitrogen Dioxide levels have fallen from 45 micrograms per cubic metre to 29, bringing the street back within required standards.
Cllr Dan De’Ath, Cabinet Member for Climate Change, Transport and Strategic Planning, said the temporary layout has proven successful in reducing pollution and meeting legal requirements. He noted that public consultation showed more than half of respondents supported reopening the road following its closure during the pandemic, when it was used as an outdoor café space. With funding now confirmed, the council is moving ahead to make the scheme permanent.
Alongside the main works on Castle Street, a series of junction improvements will take place on surrounding roads. These include changes at Westgate Street to introduce a new segregated cycleway and upgraded pedestrian crossings, layout improvements and new cycle parking along Castle Street itself, paving and street furniture changes near the Cardiff Castle entrance on High Street, and upgraded bus stops, crossings and landscaping at Kingsway. Replacement tree planting will also be provided where removals are necessary.
The council says the completed scheme will support cleaner air, safer travel, better public spaces and more sustainable movement through the city centre, while keeping traffic moving across the wider network.
