Game Theory and Junction Blocking

Game theory divides games into those in which all information is visible to all players (like chess), and those where each side holds secrets (like poker). There are different tactics in each. In a game when the position and intent of all players is visible the Nash Equilibrium -the steady state reached when every player can predict the optimal moves of their opponents and act accordingly- is easier to reach.

In junctions, it comes down to "do you block the junction or not". Here on Cheltenham Road the taxi says yes.

Then, just before the lights change, it moves forward and another car makes the same decision.

Here in this video from the St Michaels Hill roundabout, you can see another taxi making the same decision.

In highway-code theory, blocking junctions is selfish and can lead to total gridlock.

In Game Theory, as applied to Bristol City streets, blocking the junction is the correct thing to do. why?

1. You know that nobody is going to penalise anyone who blocks a junction.
2. If you block a junction, when the road ahead eventually moves, you will get through.
   
3. If the other players in the game -the other vehicles who get time at the lights, block the junction, you don't get a chance to drive yourself, hence will never make progress.
4. You are therefore forced to pull out and block the lane -if you know the other players will do the same thing.
5. The other players know the same thing, -that your best strategy to make progress is to pull out and block the lane.
   
6. Therefore they will pull out and block the lane themselves, as it is the only way they make progress.
7. Therefore your best strategy, given your knowledge of their best strategy, is to pull out.

This is the Nash Equilibrium: the steady state where no player in the game has any incentive to change their strategy. If any driver at the front of the lights doesn't pull out and block the junction, all they will do is annoy the cars behind.

This is why drivers in the city don't get annoyed by other cars doing this. They'd do the same thing. The only way to change this would be to change assumption (1), that there is no penalty for blocking a junction.

Game Theory: the maths you can play on the commute. Even if you don't realise it.

Absolute Vehicle Care Ltd, selling Alloy wheels to outsiders who inconvenience us

Dear info@absolutevehiclecare.com.

Thank you for posting your comment on our alloy wheels are for outsiders posting.

We are aware that we are the highest ranked site when you search blogspot for alloy wheels, and therefore that a comment with some banal chat and back links to your own site would help your page rank. However, as well as using nofollow links to remove them from google's PageRank scores, we have a policy that says if you spam us with attempted to links, we only make fun of you. Therefore, please accept this posting as a gift, but note that the nofollow tag above renders your link worthless and all that you will get is more spam to your email address. Sorry.

There is no point trying to push alloy wheel services to our readers, despite our broad readership in Bristol, because (a) you have a Southampton postcode and are therefore unimportant, and (b) we don't think alloy wheels have a place in the city.

Every driver who has alloy wheels values their wheels. Not only does this prevent them doing operations in the city, it holds up other traffic. Takes this video of the bottom of St Michael's Hill from last month.



The car in front of us is waiting to turn slide into the left turn lane -which has a green light onto Park Row. But it cannot do that as the car in front of it values their wheels too much to scrape against the kerb or to commit more aggressively and get both wheels entirely on the pavement, and they still have a driver-side wingmirror to lose. The selfish decision of the first car to have alloy wheels not only slows them down, it slows down the rest of the city's traffic. And this is on a Sunday! Imagine how much congestion one selfish alloy-wheel owning outsider would cause on a busy weekday morning!

Drivers who value their vehicle's bodywork and paintwork are as much an inconvenience to us locals as pedestrians on zebra crossings and cyclists pootling along. You may not realise this as you live in the provinces and dream of day trips to Portsmouth where you can see three cars in a row, but we city folk know the harsh truth: from a game-theory perspective, alloy wheels place you at a disadvantage. They are easily damaged and, as they are a visible status symbol, everyone else sees that you value your car, therefore are more likely to give way on high conflict roads, such as here, the Horfield Road/St Michael's Hill junction.

Please do not bother posting any more spam advertisement comments, as we will only continue to criticise you for your naive lack of understanding of modern driving techniques and issues, as well as your complete ignorance of game theory and its application in city driving.

Thank you,

The Bristol Traffic Team.

Proof that parking restrictions create traffic problems

We recently nipped over to Cotham Hill was to see if another rumour -parking restrictions removed- was true.

And yes, you can see, while they are resurfacing this road there are no limited waiting markings on the right-hand side of the photo, no double yellows on the other, even the zebra-crossing zig zags are gone.

And look! No vans forced to park on either pavement, leaving the approaching pedestrian to walk down the pavement without getting in our way on the road (merely the pavement, of course), no congestion caused by delivery vans forced to park half on the road, half on the pavement, no meandering cyclists in our way.

This provides clear proof that the cause of congestion is not traffic lights, the way our fellow travellers, the Drivers Alliance, or bus lanes, the way our-man-in-whitehall so believes. No, it is the restrictions on drivers parking where they need to that causes traffic problems in British cities!