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VIC Some Math from the TAC

Discussion in 'Politics, Laws, Government & Insurance' started by MV, May 23, 2012.

  1. I wrote to them regarding their ad a while ago & I just got this reply:

    I have only had a quick read through, but thoughts?

  2. I've passed it on to a physicist of my acquaintance for his comments.
    • Like Like x 1
  3. Groovy. To be honest, I was surprised I got a reply, even more surprised that it appears to be addressing what I wrote, rather than just a canned response.
  4. #4 joetdm, May 23, 2012
    Last edited by a moderator: Oct 24, 2015
    So they admit smidsy is our biggest killer and spend hundreds of thousands blaming a variable such as speed that may or MAY NOT avoid a collision but not on the one ABSOLUTE WAY OF AVOIDING A COLLISION which is giving way when you're supposed to.
    Then they tell us they can blame us on top of that with their case law rubbish.
    And the very next smidsy fatality pathetic cop sings their blame moto song.

    Also shows how they used their, vicride programs, etc, as basis for latest campaign.
    And its quite obvious they don't understand how riders feel about smidsy..

    Oh, and its also quite clear, they don't have any real riders amongst them.

    They make me sick!

    • Like Like x 1
  5. s= ut+1/2*at^2
    v = u +at
    v^2 = u^2 + 2as

    Pretty straight forward really. I expect the maths to be accurate.

    Of course the whole issue with the maths is based on two points.
    1. Taking the 15th percentile reaction time. I don't know where they pulled their data from, but that's properly terrible use of figures.
    2. Needing a skid to be able to work any of it out. If the rider used the tiniest amount of front brake it would make the calculation inaccurate, if he used a goodly amount it would be way out. I would also like to know where their assumption for the coefficient came from - not saying it's wrong, just uncredited.

    Even with a skid they would still have absolutely no idea about what speed he impacted and hence what speed he was traveling. Saying that because he flew this far he impacted at x km/h is rubbish and wrong and they know that.
    • Like Like x 1
  6. hoo ****ing rah. now please do something about it
    no not this. do something that actually addresses the problem
    evidence please? they even hit us when we are stationary!
    legal does not always equal appropriate, and appropriate does not always equal legal. and like I said, they even hit us when we are stationary
    • Like Like x 1
  7. So why when AMCN did it in real life did they come up with different results?

    Get copy today guys. AMCN deserve our financial support for what they did this month.
    • Like Like x 2
  8. Several.

    Smee was right. Again. Shouted it from the rooftops, and it went unheeded.

    The result of riders filling out TAC/Spokes/MUARC agenda-biased surveys.

    25%+ of riders surveyed (total number not given) self-reported speeding 50% of the time.

    So 12.5%+ of this 25%+ of total unknown reported speeding ‘all or most of the time’.

    Any questions qualifying rider responses in the surveys, eg.“by how much”, “ where & why (place & reason)”?

    So, extrapolating the survey & crash stats, 25%+ of riders are responsible 50% of the time for up to 80% of all crashes that occur at intersections because they were speeding causing the driver not to see them. Maybe.

    $X million (including compulsory riders levy) was spent to tell this 25%+ they were to blame for up to 80% of intersection crashes. Maybe.

    1 step forward, 2 steps back.

    TAC wants to see this incidence of self-reported speeding reduced.

    Think it’s fair to anticipate can expect more surveys.

    The choice = lie, comply ... or simply don’t rise to the bait (choose a fresh angle).

    • Nice work in eliciting the response, MV.
    • Like Like x 1
  9. At the end of the day, they have applied the same assumption to both sets of data, so while the stopping distances might be way off whats real, for comparison, it isn't the smoking gun that destroys this ad. I'm far more concerened with the lack of fault placed on the driver, the lack of explaining any other safety measures motorbikes can use and the anti motorcycling message it sends.

    As for physics, the vital thing that is the differences between crashing and not crashing is the time it takes the car to travel 6m. They put this at 3 seconds. Next time you're riding around town have a look how long it takes cars to clear a path when turning out of a side street. I've been watching this since the ad came out and the longest i've seen is 2 seconds, most less than 1.
  10. Just quickly Lilly, what speed is the bike travelling at when it gets to the car if it is doing 60?
  11. #12 joetdm, May 23, 2012
    Last edited by a moderator: Oct 24, 2015
    I struggle with their physics too!

    I've t-boned a car with my pushy twice in smidsys both times doing over 30kph.
    First one I slid along (not high over) bonnet, second I slid similarly along boot.
    No where near the energy to hoist me (or a light pushy) that high and far in the sky the vertically head first into the road as shown in the cga bullshit ad..

    They don't understand how fake it appears to riders because they don't ride.

    • Like Like x 1
  12. Might seem weird, but... 0. Assuming all things remain equal he stops 4m short.

    after 1.5 seconds, traveled 25m has 24m left.
    from 16.66 m/s will stop in 20.2m.

    stopping distance from 68km/h is 26m using their values. But it's worth remembering that their values are absolute maximum. Ie, with back wheel locked the furthest possible stopping distance is 26m at 68 and 20.2m at 60. Certainly easy to stop in shorter distances than that. 30km/h might sound like a high impact speed, but stopping dist is only 5.3m further. if you double the speed stopping distance increases 4x.
    • Like Like x 3
  13. Current AMCN has a first-class article on all this.

    Their best braking distances on an R1 (including reaction times)

    60km/hr 31.85m
    68km/hr 34.97m
    80km/hr 45.8m

    excluding reaction times:

    60km/hr 15.25m
    68km/hr 16.07m
    80km/hr 23.28m

    rear brake only - 68.2m

    They also did it on a Ducati Multistrada with ABS - which consistently outbraked the R1.

    So a competent rider, braking properly, would have pulled up well short of the car - even from 80 km/hr.

    I wonder what the laws of physics are in the TAC's alternate universe?
    • Like Like x 3
  14. interesting. Reaction times a close to a second.
  15. Just asking because in the ad it shows the bike doesn't stop at 60 but goes around the back of the car. So I assumed that neither would stop in time and the main difference preventing the crash (excluding severity of crash) was that the extra time it would take to reach the very very slow moving car and whether it would clear in time.

    Anyway that wrecks that theory. I wonder why they show the slower bike not stopping in time, but avoiding the car?
  16. Actually, this is wrong. Hate to say it. Google is your friend.

    The TAC have never justified how they got the 30km/h figure though. Even the answer they provided MV, which is almost carbon copy of what they gave VMC, doesn't justify the impact speed determination.

    The maths however, based on -0,7g and 1.5s reaction time from 49m away, starting speed, impact speed, all hangs together... but these are all typical figures from the reconstructionist handbooks, so it's an entirely contrived scenario.
  17. #18 twistngo, May 23, 2012
    Last edited by a moderator: Oct 24, 2015

    don't forget conservation of momentum. think it goes like this but its a while since I did any physics

    300kg of bike and rider at 30k. 200kg of bike stops dead, 100kg rider continues at 90k

    cause the pushy is lighter it doesn't happen to the same extent

  18. Yep, at 60km/h and -0.7g after a 1.5sec reaction time from a 49m starting point, the bike would have stopped short.

    However, if the only braking came from a skidding rear wheel, -0.4g's is as much as you can hope for, even with ABS (unlinked brakes assumed).

    Is -0.7g's a reasonable deceleration? Yes, if front brake was used.

    Is it reasonable in the depiction? NO. The front forks are not compressed - which is what you'd expect with the front brake applied.
    SNAP SHOT Forks.

    I've enhanced the screen cap and it clearly shows a whole lotta upside down fork on display!

    SNAP SHOT Forks close up.
  19. Jeez you have been studying this closely. Next you will be telling me that you can clearly see an alpine bird in the cars side mirror and that clearly they haven't taken into account the effect the altitude would be having on tyre pressure and hence stopping distance.
    • Like Like x 4