The scheme involves construction of a new interchange between junctions 10 and 11 of the M56, linking the motorway to the A533 close to Runcorn. The aims of the scheme are to reduce congestion and delays, particularly at junction 11 which is presently the main junction for Runcorn, as well as provide enhanced access to the new Mersey Gateway bridge.
There are two possible designs for the junction which will connect to the end of the Southern Expressway. The present end of the Expressway is laid out to allow for construction of a flyover, for further expansion of Runcorn New Town which never took place, but neither plan for the new interchange will make use of this opportunity.
Highways England have announced their preferred option (Option B). This is to replace the existing roundabout with a traffic-light controlled crossroad, stating that this is safe and has higher capacity than the alternative (conversion to a "throughabout"). A second roundabout south of the motorway will now not be built to prevent dangerous queues backing up.
With thanks to Janusz for information on this page.