Posted minimum speeds, was Re: Fuel Efficient Cars (was Oil Economics)

From: Michael M. Butler (mmb@spies.com)
Date: Thu Feb 06 2003 - 00:10:54 MST

  • Next message: Russell Blackford: "RE: Fuel Efficient Cars (was Oil Economics)"

    BillK wrote:
    > Ronh wrote:

    >>My VW would not hold minimum speed in our hilly areas. Many of our
    >>high ways have posted minimum speed and my car would not maintain that
    >>speed.

    > I have never heard of a minimum speed limit in UK. I don't know about
    > Europe.

    As yet another curious emergent-behavior thing about humans...

    Years ago, I used to see a highway minimum speed posted in Ohio of 40 mph.
    So I asked my brother, who was studying to be a highway planner, why.

    Apparently there was said to be evidence that at a speed a bit lower
    (around 38 or so, IIRC), driving behavior transitions from "cruising" to
    "stop-start"; this contribution to the "rubbernecker effect" can create
    a standing wave (soliton) slowdown that persists. And of course if the
    traffic feeding to that spot is numerous and fast enough, the slowdown
    spreads backwards. I conjecture that one critical factor is how drivers
    _pass_; if they slow down more precipitously when passing a sub-40-mph
    car than they do when both are traveling over 40, there you have your
    bottleneck.

    I daresay most of the people stuck in bumper-to-bumper 3 mph traffic jams
    think no deeper than that the minimum speed is some kind of sick joke.
    I'm not sure how much positive effect those minimum speed signs have.

    Anyway, that's my story. There might be other reasons for those limits, too.

    MMB

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