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Riddle me this... Fwy Traffic

Discussion in 'The Pub' started by booga, Dec 21, 2007.

  1. Lets start a new range of topics, entitled "Riddle me this" :grin:

    I was going to post this earlier, but in light of the thread ( https://netrider.net.au/forums/viewtopic.php?t=47233 ) I thought I'd ask a question...

    Why do Freeway/ Toll ways slow down?

    I get onto the SE at Punt Rd some afternoons and there is no understandable cause the traffic goes from lightning fast to slam on the brakes before you smack the car infront... WHY with the stop-start-slam breaks-repeat??

    You get traffic from the tunnel and from Punt road, each has their own lane, why is it so that we have stop start traffic...

    IS it just the tools that are driving erradically, causing the un-confident/ compitent (and perhaps old) people to jam on the breaks because the other guy pulled into their 100mtr buffer zone?

    To me it doesn't make sense, you get on, you drive at 90-100km/h, depending on lane choice, and you move over to get off at your stop, there are as many people getting off as there are getting on, so we're not trying to jam 10 people into a phone booth here...

    Personally, I sit in the right hand lane until a few km's before the exit i want, and then slowly move over.
    And I DO obey the "keep left unless overtaking" signs, esp on the Frankston Fwy, unless its peak hour and both lanes are blocked anyway (see issue #1 ;) )

    Pls Explain... :p
  2. My theory is it's due to those cars that change lanes every few seconds cutting in front of people and forcing them to brake. Cars behind them then have to brake creating gaps further down encouraging more knobheads to swerve between/across lanes and so on till eventually no one is going anywhere. Usually tends to occur worse around on/off ramps where you have traffic merging in trying to get to the right lane and traffic in the right lane trying to get to the left. Sadly most drivers lack the ability to plan ahead.
  3. It's funny isn't it.

    Two things p me off; rubber necking and people who don't know how to merge.

    I'm lucky enough to be on holidays but last week when those kids had a prang on the Westgate freeway the traffic has been doing less then 40KMph outbound. Once you reach the site it's like the green light races, we're all screaming up to 100KMph as fast as possible.

    Then I get to the Western Ring Road interchange, where traffic is lite, yet it still slows down while idiots try and merge... for god sakes, it's one lane of traffic merging... what can be so hard?
  4. +1
    The 'concertina effect' has a huge effect. I can't remember what show i saw it on, but they described a phenomena called the ghost crash.
    for e.g. if an accident/breakdown occurs on the freeway and it effects traffic, it can continue to do so for up to two hours after the problem has been cleared.
    Even if it's a minor event, as long as it's enough to slow cars down.
    Worse still, the other side of the freeway can be effected by the 'rubber necker effect'.
    So you're putting along on your bike marveling at the freedom of it all, only to have everyone around you slam on their brakes. You procede with extreme caution convinced there's an accident or po-po up ahead, only to find there's nothing.

    Do you remember the first time they turned the Monash into a 'freeway' :LOL: and the funny buggers kept the traffic lights along it?
    It turned out to be a lemon that time too, so they came up with this ingenious solution to put up signs recommending that everybody crawl along at 40kph.
    Well that was to try and reduce the concertina effect. No-one could get their heads around doing 40 on a freeway, so they didn't.
    Eventually the signs stopped working and they were never replaced.

  5. When I was at college, one of the maths lecturers used some form of differentiation to determine the maximum velocity to achieve the maximum rate of flow on a road/bridge. There is a law of diminishing returns, hence the variable speed limits on some freeways (introduced on the M25 in the early 90's - you have not seen traffic jams until you've seen the M25 on a Friday evening!).

    Other than that, traffic merging is/has/will always be a problem. Again, the traffic lights on some freeway entrances have helped and there is a line of thought to have fewer entrances and not more.

    When I lived in the UK, I spent my entire working days travelling up and down motorways travelling to customer sites. I got to see a lot of different drivers and styles. Many people are using 100% of their thought process just to drive in a straight line at speed. They are not relaxed, won't take their eyes off the road in front of them, can barely indicate. Get them on a slip lane and they either get to the end and slow down (hard to merge) or pull into the inside lane without checking. Both ways cause inumerable problems.

    After spending many a happy hour doing the whole stop/start/grand prix thing on motorways (and seeing the accidents that result) I worked out that the best thing to do was to sit behind the trucks causing the holdup, light up a smoke, relax and follow for a few miles. All my tests showed I got to the next junction at the same time as the start/stop/start/gp drivers*

    * In the UK you drive on the left, overtake on the right. No overtaking on the left, even on motorways. Hence, on a 3 or 4 lane motorway, travelling up a hill on the north part of the M25, traffic builds up behind the trucks as the cars all merge into the outer lanes to go past. Me, I just followed the trucks (trucks cannot use the outermost lane).
  6. The other thing which I saw (probably on the same programme) was that the ghost accident moves backwards as the queue gets longer and after 30 minutes the problem spot is 2km back along from where it started.

    All it takes is someone to hit the brakes hard for some reason and a few cars in other lanes to also react and........
  7. Introduce a bend in the road and for some reason, every one backs off when they approach them. You sit in bumper to bumper traffic on the Eastern until you get to the bend then there is nothing there.

    Bloody frustrating.
  8. Of course. They gotta stop doing their make-up, talking on the phone and reading the newspaper to tackle the bend.
  9. Yep, Queueing Theory is the branch off mathematics that explains it all, and has been around for many decades. It was probably the math that I hated most. Nothing new in a model that describes the process.

    Just like a dog wagging its tail, or a pendulum, any small change at the source (top, start, ahead in a queue) is amplified initially, then dissipates at the source, but continues on through the queue like a wave. Then you get secondary, then tertiary effects. Then the math gets complicated. :roll:

    If people would just learn how to drive, and concentrate on what they are doing, then the effect wouldn't be nearly so great. But for us, we can just filter through the poor sods.
  10. I want to know who put the "70km" sign on the Blackburn Rd fly-over (monash fwy)...??? Even when I check out of work early and go through there at 2/3/4am, the tards still slow to 70... :mad: