Was that Britspeak? I didn't know that. Y'all should watch more British TV.

What's not clear here? Your 'Huh?' was less than explicit, but I'll try.

Slip Road - way on or off the motorway.

Motorway - very fast multi-lane highway with hard shoulders (mostly).

Tightening up - refers to the reducing radius of the bend in a slip road. Should ease up as you reach the part of the slip road where your speed increases. You can be in real trouble if it does the opposite or if it tightens too fast as you leave the motorway.

One way system - a section of road where, for reasons of traffic management, all traffic on the road moves in one direction. It is necessarily matched by a parallel section of road that may be a block away where traffic has to move in the opposite direction - otherwise no one gets home.

Illogical - describes something that appears to have no reason. The term was invented by a guy called Spock who wrote a book about bringing up Klingon children.