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FAQs A465 Aberdulais Roundabout- Essential Bridge Deck Refurbishment Works


Built in 1975, the 65 metre long Aberdulais Overbidge spans the A465 and the Tennant canal. The bridge is 46 years old and is in need of repair. During a recent inspection, a structural defect was identified in the columns supporting the bridge deck. 

As part of the works, there will be a series of road closures and lane closures will be installed on the gyratory with local diversions in place, see details at the link on the right. The first phase of works will include critical concrete repairs to this column. Followed by further bridge deck refurbishment and waterproofing works under full closures during the school summer holidays.

During a recent inspection, a significant structural defect was identified in the columns supporting the bridge deck. For safety, a lane closure was implemented on the bridge and a temporary propping system was installed below while the permanent repair was designed and programmed

To facilitate the repair, the road now needs to be closed to remove all traffic loading to allow the repair of the reinforced concrete column supporting the bridge deck. To prevent this defect from re-occurring the bridge deck is to be waterproofed. This will be done following the concrete repair to prevent water ingress through the deck. The full closure of the bridge is required to install the waterproofing across the full width of the bridge deck.


Critical repair work need to be completed as soon as possible to deliver a long term fix for the structural defect and to ensure motorists’ safety.

Following the identification of the defect, the design for the repair was undertaken during the lockdown period. However, due to the complexity of the design, this could not be completed in time to allow for construction to begin during lockdown

Not carrying out this work now would lead to further deterioration of the structure resulting in unplanned emergency closures causing more disruption and inconvenience than planned works.

The first phase of works will take place as follows: 

1. Full closure 24/7 for concrete repairs 23/5/21 (08.00hrs) – 28/5/21 (20.00 hrs) - 5 days 

 A full closure is required to ensure the concrete surfacing has sufficient time to cure and harden.

Following recent feedback, the decision was taken to defer the deck refurbishment to the summer holiday. The provisional programme for the second phase of works is as follows:

2. Full closure 24/7 for deck refurbishment 19/7/21 (20.00hrs) – 13/8/21 (20.00 hrs) – 4 weeks

3. Lane closures only, bridge open to traffic 14/8/21 – 13/9/21

4. Full closure night time only for expansion joint replacement (20.00 – 06.00 hrs) 13/9/21 – 24/9/21 – 2 weeks

The works include critical structural repairs to the columns and include the demolition and reconstruction of the surfacing including waterproofing to prevent water ingress through the deck. The construction programme has been developed to keep closures to a minimum, where possible works will be done under lane closure with a lane open across the bridge. 

Due to the nature of the works and health and safety requirement to protect the workforce full closures of the bridge are required for 24 hours. 

Activities that do not require a road closure will be done via a lane closure allowing traffic to cross the bridge avoiding the diversion route. There is a period of nighttime closures at the tail end of the programme to install expansion joints on the bridge and a diversion route will be in place during this time.

Vehicles wishing to travel west at Aberdulais roundabout towards Tonna, Neath and Cadoxton will be diverted east on the A465 to Resolven and then west on the A465 back to Aberdulais where their journey can continue. 

The routes will be fully signed and patrolled.


Works cannot be carried out with traffic lights due to the complexity of the roundabout and layout of the junctions. 5-way traffic lights would inevitably result in delays at peak times resulting in traffic queues on the A465, A4230 and A4109 which is considered a higher risk to the public than the diversion route.

It is not possible to install a contraflow system as the bridge is not wide enough to undertake the deck waterproofing and to provide a safe working zone at the same time. The deck waterproofing is essential to prevent water ingress through the bridge which is the main cause of the current defects.

Due to the nature of the works, some activities will be undertaken at night between the hours of 20.00 hours until 06:00 the following day. Whilst some noise disturbance can, unfortunately, be expected, every effort will be made to minimise any inconvenience caused by the nosier activities being carried out earlier in the evening.

The emergency services, public and school transport operators have been informed of the closure dates and diversion route. 

The South Wales Trunk Road Agent consulted fully with the Local Authority who have in turn consulted with all statutory consultees as part of processing the traffic order process. Following feedback from the local authority and members of the public we are currently reviewing this process to ensure stakeholders are consulted at the earliest opportunity.

Frequent project updates will be provided on this website and Twitter channels: Traffic Wales South.

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