"The Other Idiot ..."

Most of the rules in the Highway Code are written to leave a margin of error, so that there is a clear 'no-mans-land' between potentially conflicting parties. If a collision occurs in this 'buffer zone', it is because both parties are at fault. If one party makes a momentary mistake, the 'buffer zone' protects both parties.

I remember reading about someone ( probably one of James Thurber's aunts or maids ? ) who just knew that it was always perfectly safe for her to blast across junctions at full speed, because everyone else had been taught to proceed with caution, and give way if necessary.
That contrasts to the Tragedy of the Commons, with the difference that the selfish person must be unique, and that she gains while all others lose.

In practice many of these safety zones are being eroded.

In fact, instead of 'clear space' between 'your space' and 'my space', people with bigger weapons have even started encroaching on the space of people without weapons. In this case, a cyclist was assaulted for 'standing his ground' when he had priority !

Once, a van driver tried to overtake a slow car, both coming towards me on a narrow two-lane country road. Because I did not move in to the verge, he practically forced the overtaken car off the road. We should not have to 'play chicken', but we don't want to give the impression that "It's OK to drive at cyclists : they will get out of the way."

Amber phase of traffic lights

By observing traffic, you would be surprised to learn that the amber phase of traffic lights does not mean "Speed up to see if you can get through before red!".

Officially, Highway Code 175 ('Must' means it's the law.)

You MUST stop behind the white ‘Stop’ line across your side of the road unless the light is green. If the amber light appears you may go on only if you have already crossed the stop line or are so close to it that to stop might cause a collision.

On one occasion, approaching traffic lights, I heard a car engine revving behind me, and looked back to see a car accelerating towards me. He stopped, but because I had been distracted by him, I had inadvertently gone through a red light.

Tailgating

Karr’s Choice - [ Beyond the Kerb ] - Truck trying to run down cyclist.

By driving too close behind a driver, you can inhibit him from braking when necessary. This leads to streams of cars indulging in lemming-like behavior entering fog banks.

Sheppey crossing crash: Dozens hurt as 130 vehicles crash - BBC News
2011 M5 motorway crash - Wikipedia
Note, however, that police and media tend to say the fog itself is to blame, not the drivers !

Cross-hatched areas between lanes

Stop well within the distance you can see to be clear

Looking out for each other

Other factors
As well as the actions of people directly involved, additional safety factors such as vehicle design and road infrastructure design play a part. Regulation, and enforcement, too.

What we need to do is bring back
"After you, Claude. No, after you Cecil"

Police encouraging Safe Margins ?

Life on the roads is so much better if people (of all kinds) don't 'drive' to the limit of what they think they can get away with legally. It is good to have a 'Safety margin' that could be used by either party in emergency or accidentally, but which both parties could legally use. It is best if neither party uses it, then everyone is very safe. It is possible that the police will encourage drivers and cyclists not just to obey the letter of the law, but to stay well within the law, and well within limits of what is safe. See the 'Prisoner's Dilemma' in 'Game Theory' - if both parties play nicely, everyone wins, but if one party encroaches on the other's safety margin, then the latter will also tend to occupy the safety margin, to exclude the other.

Fine for tailgaters having limited impact - [ AA ]

"29% of drivers say they have modified their driving since the changes came in : 74% say they have not noticed a change in other drivers’ behaviour."

See also

Lemmings - Peer Pressure - Race to the Bottom - [ Motorism - a failure of democracy ! ]

• Heading to France? Pedestrian priority laws have changed! - [ MIND over MOTORCYCLE ]
• 'I stay safe in the city by assuming everyone is an idiot', says cyclist (63) - [ Independent.ie ]

• Overtaking a cyclist - [ Advanced Driving ]
  In defence of motorists - [ CycleChat Cycling Forum ]
  entitlement, responsibility, contingency
• "Why is congestion and traffic caused by other cars seen as inevitable, while a cyclist mostly viewed as an obstruction? #driverbias" - [ James Holloway on Twitter ]