Cardiff Roundabout Approvals & Bylaws

Transportation Wales 4 Minutes Read · published February 12, 2026 Flag of Wales

Cardiff, Wales requires developers and contractors to follow council and national highway procedures when proposing new roundabouts or altering existing junctions. Approval typically involves planning review, highways agreements and technical design checks to ensure safety, drainage, visibility and adoption standards. This guide summarises the local approval pathways, design references, enforcement processes and practical steps to apply for construction or adoption of roundabouts within Cardiff.

Scope & Governing Instruments

Roundabout proposals in Cardiff are governed by the council's highways development processes, the requirement for planning permission where applicable, and formal highway agreements for works affecting the public highway. Local guidance references national design standards as applicable to adoption and safety checks [1].

Consult the council highways development team early in design to avoid delays.

Design Standards & Technical References

Designers should follow Cardiff Council guidance for highway construction and adopt national technical standards where the council specifies them, including geometry, signage and drainage. Where the council requires adoption, designs must meet the council's specification for adoption and inspection regimes.

  • Design geometry and visibility requirements: follow council specifications and national standards such as the Design Manual for Roads and Bridges or Manual for Streets where referenced by the council.
  • Construction details, materials and drainage: comply with Cardiff adoption specifications and any required testing regimes.
  • Road safety audits and Stage reviews: submit audits as required by the council during design and prior to occupation.
Road safety audits are typically required at key design stages for junction works.

Penalties & Enforcement

The council enforces highway works, unauthorised works and non-compliant construction through its highways and traffic teams. Specific monetary penalties are not consistently listed on the council pages cited; where amounts are not provided the text below states that they are "not specified on the cited page" and points to enforcement contacts [2].

  • Fines: specific fine amounts for unauthorised highway works are not specified on the cited Cardiff pages; see the council enforcement contact for case-specific fees and penalties.
  • Escalation: first offence, repeat and continuing offences escalation ranges are not specified on the cited page; enforcement action may include fixed penalties, enforcement notices or prosecution.
  • Non-monetary sanctions: the council may issue works-stopping notices, removal orders, require reinstatement to approved standards, or refer matters for prosecution in magistrates' court.
  • Enforcer: Cardiff Council Highways/Traffic and Regulatory Services enforce highway works; contact details and complaint pathways are on the council highways and Traffic Regulation Orders pages [2].
  • Inspection & complaints: inspections are carried out by council highways officers; members of the public can report unauthorised works via the council contact pages.
  • Appeal/review: appeals against enforcement notices follow the routes set out in the notice or through the courts; time limits for appeals are case-specific and not specified on the cited council pages.
  • Defences/discretion: defences may include having an approved Section 38 or Section 278 agreement, reasonable excuse, or active remediation; specific statutory defences depend on the enforcement instrument and are not listed verbatim on the cited pages.
If works affect the public highway you must secure the appropriate highway agreements before starting construction.

Applications & Forms

Key applications are typically:

  • Section 278 highway works agreement (works to the existing highway) - application details and contact on the council highways agreements page [1].
  • Section 38 adoption agreement (new streets to be adopted) - application details are provided by the council highways development team.
  • Fees: specific fee schedules for agreements are not specified on the cited pages; applicants should request a fee estimate from the council contact.
Applications for highway agreements usually require detailed drawings, a safety audit and a timetable for works.

Practical Action Steps

  • Early engagement: contact Cardiff Council Highways Development with preliminary designs.
  • Submit required forms for Section 278 or Section 38 agreements as advised by the highways officer.
  • Complete road safety audits and technical checks and respond to council technical comments.
  • Pay the council’s application and supervision fees as invoiced; request fee details in writing.
  • Arrange inspections and a final adoption inspection with the council to confirm compliance.

FAQ

Do I need planning permission to build a roundabout in Cardiff?
It depends on site context and associated development; major new junctions often form part of a planning application, while alterations to the public highway require highway agreements with the council.
What is a Section 278 agreement?
A Section 278 agreement under the Highways Act allows developers to carry out works on the public highway with the local authority's approval and technical supervision.
How long does adoption take after construction?
Adoption times vary by project and depend on completion of remedial works and passing final inspections; specific timelines are not specified on the cited Cardiff pages.

How-To

  1. Engage Cardiff Council Highways Development early to discuss the proposal and identify required agreements.
  2. Prepare detailed engineering drawings, drainage plans and road safety audits as required by the council.
  3. Submit applications for planning (if required) and for Section 278 or Section 38 agreements to the council highways contact.
  4. Negotiate and enter the appropriate highway agreement; agree a programme of works and supervision arrangements.
  5. Complete construction to the council's specification, arrange inspections and address any defects.
  6. Apply for final adoption and obtain written confirmation from the council that the new/altered roundabout is adopted.

Key Takeaways

  • Early contact with Cardiff Highways prevents design rework and delays.
  • Highway agreements (S278/S38) are typically required for roundabout works affecting the public highway.
  • Designs must meet council adoption standards and pass safety audits prior to adoption.

Help and Support / Resources

  1. [1] Cardiff Council - Highways agreements and development
  2. [2] Cardiff Council - Traffic regulation orders and enforcement

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