Driving on the A1(M), I see an awful lot of bad driving. (Not just people who run into the back of me, either.)
This takes a variety of forms. We're all familiar with the middle-lane moron - sitting there in the middle lane doing 50, effectively turning a 3-lane motorway into a single-lane queue. Then there's
the compulsive lane-changer, who will dart into any space in another lane at the first sign of delays, even if they lose out in the process. (This last habit generates a good illustration of the transition between laminar and turbulent flow.)
Often the root cause of much of the bad driving I see is sheer impatience. And the possible gains are infinitesimally small - usually you might move up one car in the queue.
But last night was just lunacy. Up the A1 there's a choke point where it goes from 3 lanes to 2. So at the merge point I'm letting a lorry into the space in front of me. All of a sudden this old banger in the inside lane swings onto the hard shoulder to pass the car merging in behind me, shoots between me and the lorry (almost at right angles), screeches up past the lorry, and swings at right angles again across the front of the lorry, back on to the hard shoulder, and disappears off to heaven knows where, with the lorry driver flashing his lights and tooting his horn.