Rant

unholyangel

AndyPix wrote: »

This is in stationary/stop-start traffic


The rest of the motorway edges on, but the **** in the 3rd lane just sits there and doesnt move until a huge gap has formed - then decides to move up and close the gap.


This is how queues are formed in the first place.
If everyone moved at exactly the same time then there would be no queues
This is , of course, not possible - But why the massive gap ?? WHY


Edit : The ones you mention are just as bad
eg pull into 3rd lane, and then do exactly the same speed as the second lane are doing - hence blocking the motorway ..


They also, should be flogged and sent to jail

Actually its caused by people driving too close to the car in front, applying the brakes then the person behind them applies the brakes when they see the person in front applying the brakes and it causes a concertina effect - stretching back miles & creating hours worth of traffic jams.

https://www.youtube.com/watch?v=goVjVVaLe10

Okay so you guys were already affected by it, but I still see the funny side in complaining about a guy not driving up peoples !!!!!! as causing queues when its actually driving up peoples !!!!!! that cause it.

Fair enough I can't see the size of the gap he's leaving. But if theres still traffic in front of him, moving up a few seconds earlier isn't going to change that.

AndyPix

unholyangel wrote: »

But if theres still traffic in front of him, moving up a few seconds earlier isn't going to change that.

GRR, yes - yes it is


Its maths/physics or the Concertina effect if you please

JP08

Hmmmm ... just knocked up a quick spreadsheet to model what you describe above.

If a driver sits still for 2 seconds then moves into the gap, and everyone else behind takes two seconds to react then you get:
10 cars back, 22 seconds delay.
15 cars back, 32 seconds.
20 cars back, 42 seconds.

Do this three times (bear with me here) and the total delays become 66, 96 and 126 seconds.

Now, have a driver that waits 60 seconds for a three car gap instead of 20 for a 1 car gap (hence the three times) and you get a rather interesting result.

10 cars back 82 seconds.
15 cars back 92 seconds.
20 cars back 102 seconds.

In other words everyone only slowly reacts once as opposed to three times and the delay is less when you get enough cars back.

esmerobbo

How big would you like the gap to be?
If you would like it to be say 1 car's length and they all moved off together they could only travel using the two second rule at 5 mph. You have to increase by at least a cars length for every 5 mph after that.
There has to be an expanding gap between vehicles simply for them to move as one.
Cant see the problem in stop start traffic, slightly different if it is just slowing traffic, but if it is stop start cant see why it matters where you wait.

Herzlos

AndyPix wrote: »

No - Its not moving when the car in front of you moves that causes queues

Nope, it's stopping that causes queues. Stopping usually because you're too close to the car in front.

Waiting a car length or so before moving off will have a dampening effect and should actually speed things up again as well as being better on fuel and wear.

Le_Kirk

AndyPix wrote: »

This is a message to the people who, in rush hour traffic, on a chocca-bloc motorway -
In the 3rd lane, leave a massive 2 mile gap between them and the car in front ...

I've told you a million times not to exaggerate!;)

Shoshannah

AndyPix wrote: »

I never thought of that - but still - No excuse - should move to the first lane

I'm confused. Wouldn't their actions have the same effect regardless of which lane they are using?

Jackmydad

The real problem is too many people trying to got to the same place at the same time.
I wonder how much of the "problem" of car spacing is perceived rather than actual.
A bit like the thing of rushing to get somewhere a few miles away, when in reality it makes little difference to the journey time.

bigadaj

The OP is absolutely wrong, the way to avoid queues is to maintain a constant speed, which is why managed motorways have come in.


Stopping and starting causes ripples and when starting the fact that, if you are at all sensible, you don't maintain a two foot gap with the car in front at 50mph, which was the case when you were queuing, results in delays and waves of traffic.


If you really want to understand traffic flows then do some more grown up reading, sophisticated traffic modeling uses principles from fluid dynamics; an example is that you are pouring out a full bottle in one go, which glugs and stops in bursts, whereas it would be quicker and more even if you gently tilt and allow the fluid to flow steadily.

Nodding_Donkey

AndyPix wrote: »

Sigh .


No - Its not moving when the car in front of you moves that causes queues


When the car in fornt of you moves, and you take a couple of seconds to respond and move, this action is magnefied all the way back by each car that it "passes".


So if 1 idiot doesnt move for say 60 seconds instead of the 3 seconds when a normal person would have moved then you can see how this action its-self is the actual cause of a lot of the actual queue.


There is a little animation somewhere to demonstrate this affect - let me dig it out

Sigh.

It's people that have to keep stopping because they drive too close that cause the holdups.

Known as the wave effect.

ETA http://www.traffic-simulation.de/