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Traffic Wales information line 0300 123 1213
The Welsh Government’s traffic information service for motorways and trunk roads in Wales

A458 Spring Bank Culvert Replacement – Welshpool FAQs


The work involves installing a new culvert beneath the carriageway to replace an existing culvert that has partially collapsed. The culvert is buried at a considerable depth beneath the carriageway, with the southern edge of the carriageway supported by a retaining wall over 6m in height. Major works are necessary to this retaining wall to install the new culvert whilst ensuring that the road remains capable of supporting traffic loads.

The diversion route is approximately 15 miles long and directs westbound drivers onto the A490 for 7 miles before turning left at the A495 junction to travel 8 miles along the A495 to re-join the A458, with eastbound drivers following the route in reverse.

The diversion route signposted is the shortest possible alternative route utilising similar or better classes of road (A roads in the case). This ensures that all vehicles – in particular HGVs – can negotiate the route safely.

Due to the depth of the existing partially collapsed culvert and the narrow width of the carriageway, the full width of the road is needed to ensure the safety of the workforce and to eliminate the risk to road users. During the works the full width of the carriageway will be excavated to the level of the culvert. Unfortunately, due to the constricted nature of the site it is not possible to carry out these works using traffic lights.

The work involves over 350m3 of earthworks, the placement of over 50m3 of structural concrete, the craning of several new culvert units as well as fencing, resurfacing and other ancillary activities. Every effort will be made to minimise disruption and reduce the length of time taken on site.

These works are essential to allow journeys to continue safely. The majority of the programme has been planned to take place during the winter months when traffic flows are significantly lower. It is not possible to pause over the half-term due to the scale and complexity of the works; however, every effort has been made to ensure these works are completed by Easter.

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