Project Description

Precast tunnel watercourse diversion, Wales


  • 230m long watercourse diversion tunnel
  • A total of 165 precast units weighing up to 20 tonnes.


  • Construction programme safely maintained during difficult weather conditions.


  • Detailed erection planning and scheduling combined with excellent on site engineering operations.


  • 7 weeks on site.

On time despite weather challenges

The structure is part of a major multi-million pound scheme to dual the Heads of the Valleys road in South Wales.

The new 230-metre long tunnel forms part of a reservoir watercourse diversion, situated some 30 metres below the widened A465 road from Brynmawr to Tredegar.

The contract on behalf of Carillion to erect the tunnel using Reinforced Earth’s TechSpan® precast concrete segments, was completed to programme despite some challenging conditions in the recent “rainy season”.

147 arch precast units

In all, PCE installed some 147 arch units weighing up to 20 tonnes each to form the tunnel and a further 18 scalloped units which were placed at the entry and exit to the structure.

Following completion of the first tunnel, Carillion then awarded PCE work on a smaller tunnel nearby using the Bebo arch system, which took just one week to complete.

Further information

Infrastructure / Civils Construction »

Precast concrete underground access shafts »

Location: Brynmawr, South Wales, UK

“We have worked successfully with Carillion in the construction sector in the past and it is significant that our expertise has now transferred to collaboration in the civils sector, which we hope will help to develop a successful partnership for the future.” 

Nickie Brown, PCE Ltd’s Managing Director.