The aim is to ease traffic congestion on the road – which runs between Worthing and the New Forest – and draw congestion away from Arundel town centre.
Proposals for the grey route include a new dual carriageway which will join up the two existing sections either side of Arundel – to reduce journey times, improve reliability and make the road safer.
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Andrew Jackson, senior project manager for National Highways Arundel Bypass, said his team have been working on plans since 2020 and a consultation is now available.
He said: ‘These plans will tackle one of the biggest traffic bottlenecks in the south east and will improve journeys for thousands of drivers on the A27, not only in and around Arundel but along the whole south coast.
‘As well as being a traffic bottleneck, the existing A27 between the Crossbush and Fontwell East junctions experiences an above average number of accidents compared with other rural A-roads.
‘Arundel is a special place and has a unique cultural heritage which is rightly protected.’
Upgrades to the A27 at Arundel will also include road improvements along the existing road through the South Downs National Park.
The grey route features new bridges spanning the River Arun, over the Arun Valley Railway and Binsted Rife, as well as a new junction at Crossbush.
Proposals also include roughly 8km (4.9 miles) of new dual carriageway, which will be built to the south of the existing A27, from Crossbush to Fontwell roundabout.
An estimated 6.6km (4.1 miles) of the existing A27 will be de-trunked.
National Highways are encouraging residents to give their feedback.
Throughout January and February, 12 information exhibitions will be held across the south of England, including six live chats where residents can ask questions about the project.
Andrew Jackson added: ‘The whole point of this statutory consultation is to talk to people and hear feedback on our plans.
‘All the information is available online to allow people to better understand how the scheme will affect them and my team and I will be out at public events over the coming weeks ready to answer people’s questions.’
Further information about the bypass can be found here, and consultation is open until March 8, 2022.