The Naked Scientists
  • Login
  • Register
  • Podcasts
      • The Naked Scientists
      • eLife
      • Naked Genetics
      • Naked Astronomy
      • In short
      • Naked Neuroscience
      • Ask! The Naked Scientists
      • Question of the Week
      • Archive
      • Video
      • SUBSCRIBE to our Podcasts
  • Articles
      • Science News
      • Features
      • Interviews
      • Answers to Science Questions
  • Get Naked
      • Donate
      • Do an Experiment
      • Science Forum
      • Ask a Question
  • About
      • Meet the team
      • Our Sponsors
      • Site Map
      • Contact us

User menu

  • Login
  • Register
  • Home
  • Help
  • Search
  • Tags
  • Member Map
  • Recent Topics
  • Login
  • Register
  1. Naked Science Forum
  2. General Science
  3. General Science
  4. Why does traffic clump together?
« previous next »
  • Print
Pages: [1] 2 3   Go Down

Why does traffic clump together?

  • 40 Replies
  • 15463 Views
  • 0 Tags

0 Members and 1 Guest are viewing this topic.

Offline MartinTheK (OP)

  • Sr. Member
  • ****
  • 135
  • Activity:
    0%
    • View Profile
Why does traffic clump together?
« on: 20/05/2009 04:53:53 »
I drive at the speed limit on cruise control.

Obviously I get passed a lot, but I notice that traffic goes by in clumps. Is there some theoretical reason (maybe someting involving entropy?) for this behavior? It is clearly unsafe to exced the speed limit by bunching up like that - even in fog.
« Last Edit: 01/06/2009 20:31:26 by chris »
Logged
 



Offline Bored chemist

  • Naked Science Forum GOD!
  • *******
  • 16259
  • Activity:
    100%
  • Thanked: 372 times
    • View Profile
Re: Why does traffic clump together?
« Reply #1 on: 20/05/2009 19:02:25 »
The soimple reason traffic gets bunched up is that it's often difficult (or ot doesn't seem worthwhile) to overtake.
Logged
Please disregard all previous signatures.
 

Offline techmind

  • Hero Member
  • *****
  • 934
  • Activity:
    0%
  • Thanked: 1 times
  • Un-obfuscated
    • View Profile
    • techmind.org
Re: Why does traffic clump together?
« Reply #2 on: 20/05/2009 22:40:58 »
If one driver chooses to go slightly slower than the car in front then the gap simply widens, but if his preferred speed is slightly greater than the car in front he will catch up with the car in front and, if it's not practical/worthwhile/too close to the speed limit to overtake, a clump begins to form.

See the very wonderful
 http://trafficwaves.org/
for more related information on applied traffic theory.

I try to be a jam-busting, fuel-economising, calming influence when I'm on the road [8D]
« Last Edit: 20/05/2009 22:52:23 by techmind »
Logged
"It has been said that the primary function of schools is to impart enough facts to make children stop asking questions. Some, with whom the schools do not succeed, become scientists." - Schmidt-Nielsen "Memoirs of a curious scientist"
 

Offline Don_1

  • Naked Science Forum King!
  • ******
  • 6889
  • Activity:
    0%
  • Thanked: 9 times
  • A stupid comment for every occasion.
    • View Profile
    • Knight Light Haulage
Re: Why does traffic clump together?
« Reply #3 on: 21/05/2009 07:31:37 »
Drivers who, for reasons best known to themselves, refuse to use the nearside lane prevent faster drivers from overtaking, so you get a long line of vehicles stuck behind. This is particularly the case for trucks over 7.5 ton, which are barred from the offside lane and can't get passed some silly sod who is doing less than 55mph in the center lane.
Logged
If brains were made of dynamite, I wouldn't have enough to blow my nose.
 

lyner

  • Guest
Re: Why does traffic clump together?
« Reply #4 on: 21/05/2009 16:13:59 »
D1, you're such a boy racer. Just ease up and turn on the radio. Just don't get cross.

The scary thing about these bunching waves is that the back of a queue travels backwards at a fantastic rate. The people at the back of the queue may need to apply their brakes extremely quickly to avoid piling into the guy in front. These new fangled elevated brake lights are a real godsend under those conditions. It needn't be too much of a surprise when the guy in front slows down sharply when you can see three or four cars ahead applying their brakes.
Logged
 



Offline Don_1

  • Naked Science Forum King!
  • ******
  • 6889
  • Activity:
    0%
  • Thanked: 9 times
  • A stupid comment for every occasion.
    • View Profile
    • Knight Light Haulage
Re: Why does traffic clump together?
« Reply #5 on: 21/05/2009 16:29:04 »
Quote from: sophiecentaur on 21/05/2009 16:13:59
D1, you're such a boy racer.

BOY!!!! Crumbs, me a boy!!! Thank you. I shall print this out and show others that I am a BOY, Not a old git.
Logged
If brains were made of dynamite, I wouldn't have enough to blow my nose.
 

lyner

  • Guest
Re: Why does traffic clump together?
« Reply #6 on: 21/05/2009 17:42:08 »
Boy racing is a state of mind - not chronological phenomenon, dear boy!
Logged
 

Offline rosy

  • Naked Science Forum King!
  • ******
  • 1015
  • Activity:
    0%
  • Thanked: 1 times
  • Chemistry
    • View Profile
Re: Why does traffic clump together?
« Reply #7 on: 21/05/2009 18:37:19 »
Quote
Drivers who, for reasons best known to themselves, refuse to use the nearside lane prevent faster drivers from overtaking, so you get a long line of vehicles stuck behind. This is particularly the case for trucks over 7.5 ton, which are barred from the offside lane and can't get passed some silly sod who is doing less than 55mph in the center lane.
Of course, you get the same effect with the sort of twerps who think they have a god-given right to do 85 mph (that's 15 mph above the legal limit, for those not based in the UK) all the way from Cambridge to London and come roaring up behind those of us doing 68 mph whilst overtaking a lorry flashing their headlights, and who expect us to undertake a merge/remerge manoeuver to let them past even when there's barely space between two consecutive slow-moving vehicles to fit a car into.
They tend to be the same people who pull into the nearside lane for about a microsecond between two obviously consecutive overtaking manoeuvers even when there is no traffic behind them and no reason to do so. They also brake down to about 52 at the least sign of a speed enforcement camera, endangering those of us rolling along at legal speeds by suddenly coming to a virtual stop infront of us.
Amusingly, these are also typically the same people who complain about the "crippling cost" of fuel taxes... someone really should let them into the whole thing about air resistance, poor lambs.
Logged
 

Offline turnipsock

  • Hero Member
  • *****
  • 586
  • Activity:
    0%
  • Beekeeper to the unsuspecting
    • View Profile
Re: Why does traffic clump together?
« Reply #8 on: 22/05/2009 00:59:34 »
When one lorry overtakes another lorry it's like a rolling road block on the two 'slower' lanes. Its caused be various tolerances in lorry speed limiters and some lorries limited to 54mph and some to 56mph.

The net result is that all the cars have to move to the outside lane. What Rosy says is true, people do get annoyed at people sitting at 68 mph but its because there is a huge line of traffic.

It gets to the point where people start driving up the middle lane and undertaking everybody, then cutting out forcing people in the outside lane to brake, that car behind brakes a little more and then you get a domino effect that can end up in the outside lane being stationary for a second or two.

I have found the best way to combat this is to get alongside the two lorries and the match their speed, allowing the road to clear in front. When the lorry in the middle is clear just accelerate hard and move to the middle or nearside lane.

Repeat this manouver a few times and the jams will be behind you. Just don't stop for your tea or you'll come out into a huge jam.
Logged
Beeswax: Natures petrol tank sealant.

When things are in 3D, is it always the same three dimensions?
 



Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • 12653
  • Activity:
    0%
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Re: Why does traffic clump together?
« Reply #9 on: 26/05/2009 12:50:52 »
Middle lane hoggers are a menace. I remember 1 particular occasion when I was driving from London to Cambridge (yes,Rosy - the M11 again!) at around 3am. There was no traffic at all and suddenly, there in front of me, was a car in the middle lane. I was doing about 75-80mph at the time (yeah, I know) and caught the car up so fast it couldn't have been doing more than 55-60mph. I had to change from the nearside lane to the outside lane & back again to get past.

But, back to the topic. What Turnipjock said is absolutely right. People pulling into the outside lane and forcing others to brake is a major cause of bunching.

Whilst I agree with Rosy's point about people driving at 85mph, I have often been forced to drive at speeds up to 90mph in the outside lane because that seems to be the average speed. I don't want to be stuck behind 60mph middle lane hoggers or lorries that take 5 miles to overtake other lorries. On more than 1 occasion I've been forced up to almost 100mph to get into the outside lane to overtake (that seems particularly the case on the M1).
Logged
 

Offline dentstudent

  • Naked Science Forum King!
  • ******
  • 3146
  • Activity:
    0%
  • FOGger to the unsuspecting
    • View Profile
Re: Why does traffic clump together?
« Reply #10 on: 26/05/2009 12:53:11 »
I was forced to do 130mph on Saturday. Ahhhh! Empty autobahns!
Logged
 

Offline DoctorBeaver

  • Naked Science Forum GOD!
  • *******
  • 12653
  • Activity:
    0%
  • Thanked: 3 times
  • A stitch in time would have confused Einstein.
    • View Profile
Re: Why does traffic clump together?
« Reply #11 on: 26/05/2009 20:14:18 »
Quote from: dentstudent on 26/05/2009 12:53:11
I was forced to do 130mph on Saturday. Ahhhh! Empty autobahns!

Oh I know. They're such a trial.
Logged
 

Offline turnipsock

  • Hero Member
  • *****
  • 586
  • Activity:
    0%
  • Beekeeper to the unsuspecting
    • View Profile
Re: Why does traffic clump together?
« Reply #12 on: 26/05/2009 23:27:25 »
I came up the M6/M74 on Sunday night, starting at Stratford Upon Avon at 0015.

I was thinking, while on the M6, there isn't a straight section on the M6 so I was switching from lane to lane in order to get the shortest line but I was still coming across people who just sat in the middle lane. It was one of my better ideas, switching lanes, as it stopped me falling asleep. I could also see which way the road was going to go with the satnav.

There was one point, on the M74, where I was slowing closing on a middle lane driver. I was on the inside lane and thought she would move over as I approached...but she didn't move. I made a big deal of going to the outside lane and then back to the nearside to pass her. She never moved out of the middle lane, I guess she was planing on doing the whole journey in the middle lane or something.

dent, I get a lot of wind noise from the sunroof at anything over 130mph...how do you get around that?
Logged
Beeswax: Natures petrol tank sealant.

When things are in 3D, is it always the same three dimensions?
 



Offline MartinTheK (OP)

  • Sr. Member
  • ****
  • 135
  • Activity:
    0%
    • View Profile
Re: Why does traffic clump together?
« Reply #13 on: 27/05/2009 06:25:18 »
interesting  comments.

I have a modest proposal to alleviate the California budget deficit which is currently heading north of 20 bevabucks.

If the safe drivers were deputized as the state traffic posse comitatus and equipped with dashboard cameras AND the law was tweaked to make it illegal to  own a car exceeding the speed limit ...

Then the people speeding past them could be mined as a good source of state revenue.

On the drive home from San Francisco last weekend I could have generated $100,000 easily.
Logged
 

Offline Don_1

  • Naked Science Forum King!
  • ******
  • 6889
  • Activity:
    0%
  • Thanked: 9 times
  • A stupid comment for every occasion.
    • View Profile
    • Knight Light Haulage
Re: Why does traffic clump together?
« Reply #14 on: 27/05/2009 11:47:49 »
Quote from: turnipsock on 26/05/2009 23:27:25
dent, I get a lot of wind noise from the sunroof at anything over 130mph...how do you get around that?

Might one suggest sticking to the 70mph speed limit!

Quote from: MartinTheK on 27/05/2009 06:25:18
..... make it illegal to  own a car exceeding the speed limit ...


Which speed limit? town, urban or motorway/autoroute/autobahn/freeway?

Quote from: MartinTheK on 27/05/2009 06:25:18

If the safe drivers were deputized as the state traffic posse .....

..... those who dislike them would run them off the road, shoot them and torch their car.

I think there is enough 'road rage' as it is and the US position regarding guns would make matters 100 x's worse.

Quote from: MartinTheK on 27/05/2009 06:25:18

Then the people speeding past them could be mined as a good source of state revenue.

On the drive home from San Francisco last weekend I could have generated $100,000 easily.

In the UK drivers are already clobbered with fines for driving, parking, farting and just about everything else.
Logged
If brains were made of dynamite, I wouldn't have enough to blow my nose.
 

Offline dentstudent

  • Naked Science Forum King!
  • ******
  • 3146
  • Activity:
    0%
  • FOGger to the unsuspecting
    • View Profile
Re: Why does traffic clump together?
« Reply #15 on: 27/05/2009 12:17:16 »
Quote from: turnipsock on 26/05/2009 23:27:25
dent, I get a lot of wind noise from the sunroof at anything over 130mph...how do you get around that?

That's EASY! I don't have a sunroof...
Logged
 

Offline MartinTheK (OP)

  • Sr. Member
  • ****
  • 135
  • Activity:
    0%
    • View Profile
Re: Why does traffic clump together?
« Reply #16 on: 27/05/2009 15:38:18 »
It's already possibly worth your life to stick your tongue out at other drivers in California.

We can make the dash cams very inconspicuous and if 2 % of the cars on the road are possee members...

I don't know about UK drivers, but anybody in an SUV in California is obviously a rich class traitor who deserves to be clobbered by taxes for the common good.

NB Gas in California is currently about $2.50 when it was over $4.00 they would slow down to a slight degree. At $24.50 a gallon -- madness takes control.

How about this - scratch the posse idea. Let's issue letter's of marque band pay 5% of the fines recovered to the road privateers.

Arrrh, me hearties! Were out for gold, so we are -- even though it looks like were innocentlyyoff to the market.
Logged
 



lyner

  • Guest
Re: Why does traffic clump together?
« Reply #17 on: 31/05/2009 16:39:04 »
People are obsessed with going fast!
The problem is that people CHOOSE a lifestyle which involves longer journeys than are good for them. It's a vicious circle based on peer pressure and the consumer society. I know that many people feel that they have no option but many of them, if fact, do have a choice.
If it really is as upsetting as they make it out to be, then they should consider a different choice of workplace / living place / holiday destination and reap the benefit.
I expect strong replies from a few who claim to have no choice but . . . .
Logged
 

Offline turnipsock

  • Hero Member
  • *****
  • 586
  • Activity:
    0%
  • Beekeeper to the unsuspecting
    • View Profile
Re: Why does traffic clump together?
« Reply #18 on: 31/05/2009 21:22:35 »
When I was driving back from London to Glasgow, for work, I spotted several middle lane hoggers.




Like this guy.
Logged
Beeswax: Natures petrol tank sealant.

When things are in 3D, is it always the same three dimensions?
 

Offline dentstudent

  • Naked Science Forum King!
  • ******
  • 3146
  • Activity:
    0%
  • FOGger to the unsuspecting
    • View Profile
Re: Why does traffic clump together?
« Reply #19 on: 31/05/2009 22:09:06 »
Quote from: turnipsock on 31/05/2009 21:22:35
When I was driving back from London to Glasgow, for work, I spotted several middle lane hoggers.

Clumping not too much of a problem, there though, eh? [;)]
Logged
 



  • Print
Pages: [1] 2 3   Go Up
« previous next »
Tags:
 

Similar topics (5)

Was: Dinosaur traffic jams Now: Multiple Universes (or Versii)

Started by tr1Board Physics, Astronomy & Cosmology

Replies: 12
Views: 7046
Last post 29/08/2007 23:20:52
by neilep
How do traffic lights detect the approach of a car? Do they use magnetism?

Started by SeanyBoard Technology

Replies: 13
Views: 14483
Last post 09/04/2008 00:50:49
by Seany
Should I block incoming Cyveillance traffic to my domain?

Started by tkadm30Board Geek Speak

Replies: 0
Views: 1067
Last post 23/07/2017 15:09:08
by tkadm30
MOVED: Dinosaur traffic jams

Started by JimBobBoard That CAN'T be true!

Replies: 2
Views: 3278
Last post 25/08/2007 01:07:50
by JimBob
What does work to rule mean for air-traffic control?

Started by thedocBoard Technology

Replies: 2
Views: 2472
Last post 02/08/2013 15:32:45
by Lmnre
There was an error while thanking
Thanking...
  • SMF 2.0.15 | SMF © 2017, Simple Machines
    Privacy Policy
    SMFAds for Free Forums
  • Naked Science Forum ©

Page created in 0.237 seconds with 83 queries.

  • Podcasts
  • Articles
  • Get Naked
  • About
  • Contact us
  • Advertise
  • Privacy Policy
  • Subscribe to newsletter
  • We love feedback

Follow us

cambridge_logo_footer.png

©The Naked Scientists® 2000–2017 | The Naked Scientists® and Naked Science® are registered trademarks created by Dr Chris Smith. Information presented on this website is the opinion of the individual contributors and does not reflect the general views of the administrators, editors, moderators, sponsors, Cambridge University or the public at large.