Why highways move more swiftly when you force cars to crawl along at55 mph.

In article > , Arif Khokar
says...
>
> On 10/18/2011 11:40 PM, Steve Sobol wrote:
> > In article<87c4fd67-df58-4a76-a0f9-5278e40b58d8@
> > 13g2000prp.googlegroups.com>, Harry K says...
> >
> >
> >> And the same is true for the ones trying to drive 40mph over the
> >> limit.
> >
> > Can't argue with that.
>
> Like one of those construction zones where there isn't any work in
> progress (not started yet or already completed for weeks) with a
> statutory speed limit of 45 mph on a highway with a normal free flow
> speed of 80 mph.

Completely irrelevant. The problem is people driving on the same patch
of highway at vastly different speeds, which happens both inside, and
outside, of construction zones.

--
Steve Sobol - Programming/WebDev/IT Support

On Oct 16, 11:00*am, Harry K > wrote:
> On Oct 16, 6:26*am, gpsman > wrote:
>
>
>
>
>
> > Go Slow To Go Fast
> > Why highways move more swiftly when you force cars to crawl along at
> > 55 mph.
>
> > Slate Magazine
> > By Tom Vanderbilt | Posted Wednesday, Oct. 12, 2011, at 3:19 PM ET
>
> > There is no more common lament voiced by the American driver than of
> > the one about the “idiot” in the “fast lane” who’s slowing down
> > traffic. If everyone could just drive faster, the thinking goes—if we
> > could only cull the weak gazelles in our furiously charging migration—
> > we could stamp out congestion.
>
> > We equate speed in traffic with efficiency. In the U.K., the Tory
> > government is currently advocating raising the speed limit on certain
> > motorway sections to 80 MPH, anticipating a massive windfall in
> > economic productivity and time saved. It’s speed as the health of the
> > state! (Though not all projections are so rosy.)
>
> > But one thing that tends to be lost on the individual driver, who
> > through the proscenium of his windshield commands what he believes to
> > be an empirically incontrovertible perspective on the ground truth of
> > traffic, is that sometimes you have to go slower to go faster.
>
> > Full article:http://www.slate.com/articles/life/t...lling_speed_ha...
> > *-----
>
> > - gpsman
>
> lots of print space used to sum up what has been known since way
> back.
>
> "If everyone would just "go with the flow" traffic would move a lot
> better".
>
> Harry K- Hide quoted text -
>
> - Show quoted text -
___________________
Only problem is, the "flow" has been going 3-5mph faster on average
every decade since "horseless carriages" were invented. The posted
speed limits may be either 55 or 65 in a lot of states, but I'd
guarantee the actual "flow" is at least 10-20mph faster than it was in
the '70s. What will the flow be in 2020? 80 in slow lane, 100 fast
lane??

-CC

On 10/19/2011 12:51 PM, Steve Sobol wrote:
> In .com>, Arif Khokar
> says...

>> Like one of those construction zones where there isn't any work in
>> progress (not started yet or already completed for weeks) with a
>> statutory speed limit of 45 mph on a highway with a normal free flow
>> speed of 80 mph.
>
> Completely irrelevant. The problem is people driving on the same patch
> of highway at vastly different speeds, which happens both inside, and
> outside, of construction zones.

It really depends on whether sight lines and visibility permit larger
speed differentials. Keep in mind that 40 mph is about 60 feet /
second. Assuming you're able to see about 900 feet ahead and behind,
there's no reason why one couldn't accomplish a lane change when you can
see a vehicle approaching from behind 15 seconds in advance.

> Mathematically, that doesn't really hold true if you measure following
> distance in seconds rather than feet. Higher speeds *always* result
> in more capacity.

Good catch.

California imposes a fixed minimum following distance for trucks: 300 feet,
regardless of speed. Does anybody know if any other state has this senseless
rule? (USDOT recommends 6 seconds; my company insisted on 8, which seemed
about right when I was trucking.)

300 feet is ridiculously close at freeway speeds, but ridiculously far apart
on city streets, especially when stopped. I doubt anybody actually follows
the law in that situation, but it's one more they can nail you for if they
feel like it.

"Harry K" > wrote in message
...
> On Oct 19, 1:08 am, "Beef Supreme" > wrote:
>> "Steve Sobol" > wrote in message
>>
>> .. .
>>
>> > In article <87c4fd67-df58-4a76-a0f9-5278e40b58d8@
>> > 13g2000prp.googlegroups.com>, Harry K says...
>>
>> >> And the same is true for the ones trying to drive 40mph over the
>> >> limit.
>>
>> > Can't argue with that.
>>
>> I never, ever see anybody going 115 on the turnpike or 110 on the
>> interstate.
>>
>> And anyway, cars going 115 slow down when they meet a clump of traffic.
>> Cars going 35 don't ever speed up.
>
> My point was that 'outriders', i.e. ones doing either less or more
> dthan the flow cause the same propblems. The 40mph was only picked
> because it was in the OP. Change that to 10mph, 20 mph or whatever
> suits you. The point remains the same. It isn't only the slow pokes
> that cause problems.

I drive on the turnpike all the time, and I go about 80-85 and nobody ever
passes me. The speed limit is 75. Nobody drives 40 MPH over the limit
around here. I don't think I've ever seen anybody driving that fast.

"Harry K" > wrote in message
...
> On Oct 19, 1:08 am, "Beef Supreme" > wrote:
>> "Steve Sobol" > wrote in message
>>
>> .. .
>>
>> > In article <87c4fd67-df58-4a76-a0f9-5278e40b58d8@
>> > 13g2000prp.googlegroups.com>, Harry K says...
>>
>> >> And the same is true for the ones trying to drive 40mph over the
>> >> limit.
>>
>> > Can't argue with that.
>>
>> I never, ever see anybody going 115 on the turnpike or 110 on the
>> interstate.
>>
>> And anyway, cars going 115 slow down when they meet a clump of traffic.
>> Cars going 35 don't ever speed up.
>
> My point was that 'outriders', i.e. ones doing either less or more
> dthan the flow cause the same propblems. The 40mph was only picked
> because it was in the OP. Change that to 10mph, 20 mph or whatever
> suits you. The point remains the same. It isn't only the slow pokes
> that cause problems.

I drive on the turnpike all the time, and I go about 80-85 and nobody ever
passes me. The speed limit is 75. Nobody drives 40 MPH over the limit
around here. I don't think I've ever seen anybody driving that fast.

On Oct 19, 9:08*pm, "Beef Supreme" > wrote:
> "Harry K" > wrote in message
>
> ...
>
>
>
>
>
> > On Oct 19, 1:08 am, "Beef Supreme" > wrote:
> >> "Steve Sobol" > wrote in message
>
> ...
>
> >> > In article <87c4fd67-df58-4a76-a0f9-5278e40b58d8@
> >> > 13g2000prp.googlegroups.com>, Harry K says...
>
> >> >> And the same is true for the ones trying to drive 40mph over the
> >> >> limit.
>
> >> > Can't argue with that.
>
> >> I never, ever see anybody going 115 on the turnpike or 110 on the
> >> interstate.
>
> >> And anyway, cars going 115 slow down when they meet a clump of traffic..
> >> Cars going 35 don't ever speed up.
>
> > My point was that 'outriders', i.e. ones doing either less or more
> > dthan the flow cause the same propblems. *The 40mph was only picked
> > because it was in the OP. *Change that to 10mph, 20 mph or whatever
> > suits you. *The point remains the same. *It isn't only the slow pokes
> > that cause problems.
>
> I drive on the turnpike all the time, and I go about 80-85 and nobody ever
> passes me. *The speed limit is 75. *Nobody drives 40 MPH over the limit
> around here. *I don't think I've ever seen anybody driving that fast.- Hide quoted text -
>
> - Show quoted text -

So you just ignore what I jusst posted?

On Oct 19, 3:02*pm, ChrisCoaster > wrote:
> On Oct 16, 11:00*am, Harry K > wrote:
>
>
>
> > On Oct 16, 6:26*am, gpsman > wrote:
>
> > > Go Slow To Go Fast
> > > Why highways move more swiftly when you force cars to crawl along at
> > > 55 mph.
>
> > > Slate Magazine
> > > By Tom Vanderbilt | Posted Wednesday, Oct. 12, 2011, at 3:19 PM ET
>
> > > There is no more common lament voiced by the American driver than of
> > > the one about the “idiot” in the “fast lane” who’s slowing down
> > > traffic. If everyone could just drive faster, the thinking goes—if we
> > > could only cull the weak gazelles in our furiously charging migration—
> > > we could stamp out congestion.
>
> > > We equate speed in traffic with efficiency. In the U.K., the Tory
> > > government is currently advocating raising the speed limit on certain
> > > motorway sections to 80 MPH, anticipating a massive windfall in
> > > economic productivity and time saved. It’s speed as the health of the
> > > state! (Though not all projections are so rosy.)
>
> > > But one thing that tends to be lost on the individual driver, who
> > > through the proscenium of his windshield commands what he believes to
> > > be an empirically incontrovertible perspective on the ground truth of
> > > traffic, is that sometimes you have to go slower to go faster.
>
> > > Full article:http://www.slate.com/articles/life/t...lling_speed_ha...
> > > *-----
>
> > > - gpsman
>
> > lots of print space used to sum up what has been known since way
> > back.
>
> > "If everyone would just "go with the flow" traffic would move a lot
> > better".
>
> > Harry K- Hide quoted text -
>
> > - Show quoted text -
>
> ___________________
> Only problem is, the "flow" has been going 3-5mph faster on average
> every decade since "horseless carriages" were invented. *The posted
> speed limits may be either 55 or 65 in a lot of states, but I'd
> guarantee the actual "flow" is at least 10-20mph faster than it was in
> the '70s. *What will the flow be in 2020? *80 in slow lane, 100 fast
> lane??
>
> -CC- Hide quoted text -
>
> - Show quoted text -

What problem? As long as the "flow" speed is safe for the highway
that is the most efficient speed. It is speed differential that is
the problem (causes traffic turbulance), not speed per se.

From a lifetime of driving I use "posted plus 10 percent" as a fairly
safe "ticketless drive" and it seems to fit right in tiwht the flow
everywhere I have been (49 of the 50 states). Of course I haven't
been out of this local area now in ummm....30 some years other than
400 miles to BC over 2 lane roads once/year.

Harry K

"Harry K" > wrote in message
...
> On Oct 19, 9:08 pm, "Beef Supreme" > wrote:
>> "Harry K" > wrote in message
>>
>> ...
>>
>>
>>
>>
>>
>> > On Oct 19, 1:08 am, "Beef Supreme" > wrote:
>> >> "Steve Sobol" > wrote in message
>>
>> ...
>>
>> >> > In article <87c4fd67-df58-4a76-a0f9-5278e40b58d8@
>> >> > 13g2000prp.googlegroups.com>, Harry K says...
>>
>> >> >> And the same is true for the ones trying to drive 40mph over the
>> >> >> limit.
>>
>> >> > Can't argue with that.
>>
>> >> I never, ever see anybody going 115 on the turnpike or 110 on the
>> >> interstate.
>>
>> >> And anyway, cars going 115 slow down when they meet a clump of
>> >> traffic.
>> >> Cars going 35 don't ever speed up.
>>
>> > My point was that 'outriders', i.e. ones doing either less or more
>> > dthan the flow cause the same propblems. The 40mph was only picked
>> > because it was in the OP. Change that to 10mph, 20 mph or whatever
>> > suits you. The point remains the same. It isn't only the slow pokes
>> > that cause problems.
>>
>> I drive on the turnpike all the time, and I go about 80-85 and nobody
>> ever
>> passes me. The speed limit is 75. Nobody drives 40 MPH over the limit
>> around here. I don't think I've ever seen anybody driving that fast.-
>> Hide quoted text -
>>
>> - Show quoted text -
>
> So you just ignore what I jusst posted?

Somebody going 10 over or 10 under doesn't create much of a problem on
freeways, unless they're hogging the left lane or micropassing.

On Oct 20, 2:15*am, "Beef Supreme" > wrote:
> "Harry K" > wrote in message
>
> ...
>
>
>
>
>
>
>
>
>
> > On Oct 19, 9:08 pm, "Beef Supreme" > wrote:
> >> "Harry K" > wrote in message
>
> ....
>
> >> > On Oct 19, 1:08 am, "Beef Supreme" > wrote:
> >> >> "Steve Sobol" > wrote in message
>
> >> ...
>
> >> >> > In article <87c4fd67-df58-4a76-a0f9-5278e40b58d8@
> >> >> > 13g2000prp.googlegroups.com>, Harry K says...
>
> >> >> >> And the same is true for the ones trying to drive 40mph over the
> >> >> >> limit.
>
> >> >> > Can't argue with that.
>
> >> >> I never, ever see anybody going 115 on the turnpike or 110 on the
> >> >> interstate.
>
> >> >> And anyway, cars going 115 slow down when they meet a clump of
> >> >> traffic.
> >> >> Cars going 35 don't ever speed up.
>
> >> > My point was that 'outriders', i.e. ones doing either less or more
> >> > dthan the flow cause the same propblems. *The 40mph was only picked
> >> > because it was in the OP. *Change that to 10mph, 20 mph or whatever
> >> > suits you. *The point remains the same. *It isn't only the slow pokes
> >> > that cause problems.
>
> >> I drive on the turnpike all the time, and I go about 80-85 and nobody
> >> ever
> >> passes me. *The speed limit is 75. *Nobody drives 40 MPH over the limit
> >> around here. *I don't think I've ever seen anybody driving that fast..-
> >> Hide quoted text -
>
> >> - Show quoted text -
>
> > So you just ignore what I jusst posted?
>
> Somebody going 10 over or 10 under doesn't create much of a problem on
> freeways, unless they're hogging the left lane or micropassing.

On a congested four lane interstate, someone doing 10 under will force
the person trying to do the speed limit to also do 10 under, as the
left lane is usually filled with people doing 15-20 over.