Building a motorway junction through the green belt at any location suggested for junction 18a will increase traffic locally, increase pollution, increase noise, damage the environment, kill off wildlife, ruin age old villages and cost between £320,000,000-£440,000,000. 

 There is access to junction 18 through Westerleigh and access to junction 19 via 2-3 roundabouts from the ring road. 

Building another motorway junction here will increase traffic. If a motorway junction and link road is built more traffic will enter the Ring Road from the M4, planning companies will build over the Green Belt adjacent to the link road...which brings a lot more cars, more congestion and large loss of Green Belt over all.