"Earlier this month, the government announced funding for a 1.8-mile (2.9km) tunnel to remove congestion from the main road past Stonehenge.
It doesn't need a stinking tunnel.
Just finish widening the road up to the next junction.
The tunnel is going in (possibly); the idea is indeed to reduce traffic stops and the general stink and noise near a major tourist attraction. Not everyone is in favor of such projects, as the comments sections seem to indicate.