The Romans knew the importance of the A5 as Watling Street, a very ancient and important key route. However, modern day transport planners lack the same foresight and have completely failed to update it to keep up with modern day traffic demands.
You only had to see the sheer volume of traffic on there throughout the Summer holidays and the other regular busy congestion periods on there, to see that in its current form, it is not sustainable for the traffic flow that goes through there.