Why not?

As in 'Why not provide your own title'. I think most of us would know why it would be better to find a different route!
Incidentally the tarmac to the right is the cycle track. I think the car driver was trying to get onto it. Were there signs saying that the road was closed? Yes.
To the left is Maryport golf course, about half of which is now part of the Solway Firth!