A blue sign with a diagram showing a branch off the road ahead and the following text.
Forward destinations: The NORTH; Leeds; (M62).
Exit destinations: ; Wakefield; A636.
Junction number: 39.
This is Durkar Interchange, the first junction for Wakefield and the sign that we are now entering the sprawling built-up part of West Yorkshire.
Just after the junction we cross a viaduct over the River Calder that was the site of an accident where several construction workers lost their lives. It's easy to forget just what a huge engineering achievement these roads are - and what a cost some of them had.