Of the four options out to public consultation at the start of the year, the chosen route is the one furthest to the east away from the existing Britannia Bridge – the so-called purple option. It includes highway improvements at A55 Junctions 8 and 8A.
An appraisal of the options by Aecom indicated that this option offered the greatest economic benefits, best value for money and best performing in terms of highway alignment. It was also the most popular option of the public consultation with 25% of respondents selecting it as their first choice.
As part of the next stages, a procurement exercise will take place to appoint technical advisors to develop the preliminary design and prepare for publication of draft orders and an environmental statement.
Further analysis is also required as part of the next stage of development to determine which form of bridge is most suitable. Project cost will depend on this analysis.
Other options that were considered (illustrated below) include bridge alignments much closer to the Britannia Bridge or simply widening it.
Road traffic between Anglesey and the Welsh mainland currently has the option of Robert Stephenson's Britannia Bridge or Thomas Telford’s original Menai Bridge, but both suffer from heavy congestion.
Wales’ first minister Carwyn Jones said: “The A55 is important locally, nationally and internationally. It provides the main economic artery for North Wales and connects the region with the rest of Wales, the UK and Europe.
“The Britannia Bridge is the only section of the route which is single carriageway and we know this reduction in lanes leads to congestion at peak times and during the tourist seasons. There is very strong case for increasing capacity across the Menai and I am delighted the Welsh government is taking action to address the issue.
“Based on the appraisal undertaken on the options, the purple option performs best and would be vital in improving journey times, strengthening the A55’s resilience, and ensuring safer travel across the Menai Strait.
“It will also provide economic benefits and ensure the route is fit for purpose as traffic volume is expected to increase over the years to come.”
Cabinet secretary for economy and transport Ken Skates added: “We have made it known for a long time our intention to build a third Menai crossing and today’s announcement is a significant step forward in delivering exactly that.
“The purple option provides us with an opportunity to develop a crossing which would allow people to seamlessly cross the Menai Strait and support future projects such as Wylfa Newydd.
“We fully understand the sensitivity of placing a new crossing over the Menai Strait and further visualisation assessment and analysis work will now take place before the bridge type is selected and taken forward to the next stage of scheme development.”