Article: Five Tips for Safer Driving

"Scott en Aztlán" > wrote in message
...
>
> So if everyone is in a traffic jam and moving at 0 MPH the road is not
> "full?"

That's a parking lot you lunatic! Not a road.

Scott en Aztlán > wrote in
:

> Andy > said in rec.autos.driving:
>
>>Brian Smith wrote:
>>> "Nate Nagel" > wrote in message
>>> ...
>>>
>>>>If the freeway is full, it won't be moving at all.
>>>
>>>
>>> It can be full and still move.
>>
>>
>>
>>The cars move, not the freeway.
>
> In some places, like California, the road moves, too.

Oh thank God! I thought it was the tequilia. <VBG> ;-) and any other
emotocon to indicate I'm kidding.

Doug

In article >,
DYM > wrote:
>Scott en Aztlán > wrote in
:
>
>> Andy > said in rec.autos.driving:
>>
>>>Brian Smith wrote:
>>>> "Nate Nagel" > wrote in message
>>>> ...
>>>>
>>>>>If the freeway is full, it won't be moving at all.
>>>>
>>>> It can be full and still move.
>>>
>>>The cars move, not the freeway.
>>
>> In some places, like California, the road moves, too.
>
>Oh thank God! I thought it was the tequilia.

That's the trouble with driving in California. Careful
as you may be, you can still spill your drink. And if
"the big one" hits, just when you need it most.

--
John Carr )

Scott en Aztlán > writes:
>Bernd Felsche > wrote:

>>>>A freeway is "full" when all lanes are at 1800 vehicles/hour.

>>>Upon what assumptions is this number based?

>>Minimum "safe" following interval of 2 seconds.

>So if everyone is in a traffic jam and moving at 0 MPH the road is not
>"full?"

It's then ZERO vehicles/hour. That's the same as when there are no
vehicles using the freeway.

The road isn't then full; nor is it delivering the nominal maximum
capacity.

The whole point of lane rating is that the number of lanes is a key
to the number of vehicles that *could* pass a length of road.

Trying to "overload" the capacity results in congestion; as does the
inability of vehicle operators to merge, exit or keep a safe
distance.
--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | "Laws do not persuade just because
X against HTML mail | they threaten."
/ \ and postings | Lucius Annaeus Seneca, c. 4BC - 65AD.

Bernd Felsche wrote:
> Scott en Aztlán > writes:
> >Bernd Felsche > wrote:
>
> >>>>A freeway is "full" when all lanes are at 1800 vehicles/hour.
>
> >>>Upon what assumptions is this number based?
>
> >>Minimum "safe" following interval of 2 seconds.
>
> >So if everyone is in a traffic jam and moving at 0 MPH the road is not
> >"full?"
>
> It's then ZERO vehicles/hour. That's the same as when there are no
> vehicles using the freeway.
>
> The road isn't then full; nor is it delivering the nominal maximum
> capacity.
>
> The whole point of lane rating is that the number of lanes is a key
> to the number of vehicles that *could* pass a length of road.
>
> Trying to "overload" the capacity results in congestion; as does the
> inability of vehicle operators to merge, exit or keep a safe
> distance.

Seems logical to me.
-----

- gpsman

Scott en Aztlán > writes:
>Bernd Felsche > said in aus.cars:
>>Scott en Aztlán > writes:
>>>Bernd Felsche > wrote:

>>>>>>A freeway is "full" when all lanes are at 1800 vehicles/hour.

>>>>>Upon what assumptions is this number based?

>>>>Minimum "safe" following interval of 2 seconds.

>>>So if everyone is in a traffic jam and moving at 0 MPH the road is not
>>>"full?"

>>It's then ZERO vehicles/hour. That's the same as when there are no
>>vehicles using the freeway.

>Obviously not. In one case there are NO cars on the road; in the other
>there are THOUSANDS.

>Let me phrase my question another way: what is the formula you used to
>arrive at the 1800 vehicles/hour figure you tossed out earlier? What
>variables are part of the formula? Hint: vehicle velocity is one of
>the terms.

This is independent of vehicle speed.

The two seconds recommended following distance is based on human and
technical reaction times. It applies to dry, sealed roads. If the
roads are usually wet, then 3 seconds _should_ be the minimum gap
between vehicles; so the rate drops to 1200 vph.

Two seconds gap means a maximum of 1800 vehicles per hour because
there are 3600 seconds in an hour.

If you want a road to get 10,000 vehicles into a city within an
hour, it'd better have at least 5 lanes. Trying to get the 10,000
cars in on 4 lanes requires a density of 2500 vhp, demanding a gap
of 1.4 seconds which is borderline in terms of drivers being
reasonably able to avoid pile-ups.

When the gap reduces to less than a second in all lanes, then
crashes become unavoidable. A slight perturbation is likely to
produce a pile-up.

In Germany, it's recommended that the gap be "half-speedometer"
being the distance in metres of the speed indicated in km/h. That
works out near enough to 2 seconds (1.8 seconds FWIW) and it's much
easier to judge 2 seconds than to judge 65 or 80 metres.

People are generally no good at judging distances unless they've
undergone a lot of training. Even then, tricky light conditions or
roadside structures can distort the perception markedly. A short
interval of 2 seconds takes about 2 minutes of training to get
within 20% or less error.

>>The whole point of lane rating is that the number of lanes is a key
>>to the number of vehicles that *could* pass a length of road.

>Understood. I'm just asking for the non-dumbed-down version.

Ahhh.. you're trying to be stupid. You're very good at it.
--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | "Laws do not persuade just because
X against HTML mail | they threaten."
/ \ and postings | Lucius Annaeus Seneca, c. 4BC - 65AD.

"Scott en Aztlán" > wrote in message
...
> Bernd Felsche > said in
> rec.autos.driving:
>
>>>>>>>>A freeway is "full" when all lanes are at 1800 vehicles/hour.
>>
>>>>>>>Upon what assumptions is this number based?
>>
>>>>>>Minimum "safe" following interval of 2 seconds.
>>
>>>>>So if everyone is in a traffic jam and moving at 0 MPH the road is not
>>>>>"full?"
>>
>>>>It's then ZERO vehicles/hour. That's the same as when there are no
>>>>vehicles using the freeway.
>>
>>>Obviously not. In one case there are NO cars on the road; in the other
>>>there are THOUSANDS.
>>
>>>Let me phrase my question another way: what is the formula you used to
>>>arrive at the 1800 vehicles/hour figure you tossed out earlier? What
>>>variables are part of the formula? Hint: vehicle velocity is one of
>>>the terms.
>>
>>This is independent of vehicle speed.
>
> That's ridiculous.
>
> Suppose you had a bunch of cars, each exactly 20 feet long. If you
> parked them in one lane, bumper-to-bumper, you could fit 5280/20 = 264
> of them into one mile. However, since they are parked, the number of
> vehicles passing any given reference point is 0 vehicles/hour.
>
> Now let's increase the speed of the cars to 1 MPH. If they remain
> bumper-to-bumper, those 264 vehicles will pass your reference point in
> exactly 1 hour. Add in a 2-second following distance between them
> (~2.93 feet at 1 MPH) and the maximum you can expect is 5280/22.93 =
> ~230 vehicles/hour.
>
> Now let's double their speed to 2 MPH. Following distance increases to
> 5.87 feet, and the maximum number of vehicles that can pass a given
> spot in the road increases to 2 * 5280 / 25.87 = ~408 vehicles/hour.
>
> Clearly the number of cars which can potentially pass any given fixed
> point during one hour varies directly with vehicle speed as well as
> vehicle length (and perhaps other things I haven't thought of). It
> seems to me that the actual formula ought to look something like this:
>
> lane capacity (vehicles/hour) = vehicle speed (miles/hour) * 5280
> (feet/mile) / (vehicle length in feet + following distance in feet)
>
> By holding the car length constant at 20 feet, plugging and chugging
> gets up the following maxima:
>
> 1070 v/h at 10 MPH
> 1342 v/h at 20 MPH
> 1466 v/h at 30 MPH
> 1537 v/h at 40 MPH
> 1584 v/h at 50 MPH
> 1616 v/h at 60 MPH
> 1640 v/h at 70 MPH
> 1658 v/h at 80 MPH
> 1673 v/h at 90 MPH
> 1685 v/h at 100 MPH
>
> Hmm... Seems to be approaching some sort of asymptotic limit...
>
>>>Understood. I'm just asking for the non-dumbed-down version.
>>
>>Ahhh.. you're trying to be stupid. You're very good at it.
>
> Yeah, I guess so. So since you're so smart, suppose you tell us what
> combination of vehicle length and vehicle speed will result in a total
> of 1800 vehicles/hour passing by a given refernce point?

I was just passsing by, and just noticed this. Are the figures above for
one lane? A freeway would be two or more lanes - I think. In LA they can
be five or six lanes, with exits and entrances changing the number of lanes
every so often. Also someone is posting from Australia?? So that might be
different. Not only are the cars on the "wrong" side of the road, they are
also upside down!


> --
> I'm a wreckless driver and damn proud of it!

gpsman wrote:
> Ed Pirrero wrote:
> > gpsman wrote:
> > > Ed Pirrero wrote:
> > > > gpsman wrote:
> > > > > Ed Pirrero wrote:
> > > > > > gpsman wrote:
> > > > > > > Scott en Aztlán wrote: <brevity snip>
> > > > > > > > Here's mine:
> > > > > > > >
> > > > > > > > "I'll stay out of your way, just as I would have you stay out of
> > > > > > > > mine."
> > > > > > > >
> > > > > > > > I call this the Golden Rule of Driving. Imagine what our roads would
> > > > > > > > be like if everyone followed this simple rule.
> > > > > > >
> > > > > > > How is it practiced?
> > > > > > >
> > > > > > > How does one remain out of everybody's way?
> > > > > >
> > > > > > Easy - strive to have the least effect on anyone else's travel. Are
> > > > > > you this dumb in real life, or just playing on the Interweb?
> > > > >
> > > > > You didn't understand the question, and you sure didn't answer it....
> > > > > so I'm dumb?!
> > > >
> > > > Spurious conclusion. I *did* understand the question(s). And they
> > > > were answered.
> > > >
> > > > I realize the answer was too simple and complete to allow for your
> > > > usual equivocation.
> > > >
> > > > I'll type more slowly, if that'll help...
> > >
> > > Take your time.
> > >
> > > Describe how you accomplish creating "the least effect on anyone else's
> > > travel"... except by not leaving home.
> > >
> > > I'll wait here.
> >
> > Ah, I nice tactic. Have me describe my actions, so you can pick them
> > apart. Except that only a complete idiot wouldn't understand what was
> > meant by the comment.
>
> I wasn't speaking to you in the first place, genius, and you needn't
> have bothered replying.

This is Usenet, "genius", and if you wanted your comments to be
private, you should have e-mailed them.

If you don't like your lack of intelligence exposed, I suggest you not
post.

> Your "simple answer" could have been provided
> by any simpleton, and it appears it was.

The answer was simple because it's not too ****ing hard to figure out
how to minimize your impact on other drivers. Sort of like Scott's
Golden Rule of Driving. Simple, easy, and to-the-point. (Well, simple
for *most* folks.)

> Assuming such an ambiguous
> statement might convey something completely and should be understood
> doesn't inspire my confidence this exchange might be fruitful.

Your ASSumption that the statement was referring only to the plural
"you" and not the singular "you" is any less egregious? Hoist by your
petard.

> > By recognizing your tactic, I destroy it.
>
> Congratulations Rumsfeld. It's not a "tactic", it's a real and honest
> question so there's nothing to be "destroyed".

Bzzzt. You went on to do EXACTLY what I predicted. So, I think we can
just take your statement as stupid or dishonest. You pick - there
aren't any other choices.

> > I keep right except to pass.
> > If the road and conditions allow, I move over to allow mergers access.
> > I choose a path that interacts least with other traffic, if possible.
>
> [Nothing wrong with those. But why not just "allow mergers
> access"...?! Since you specified moving over I think you must be
> reluctant, or incapable, of employing other techniques.]

Trying to nitpick the results, exactly as I predicted.

Did anyone mention that the list I provided would be all-inclusive,
and/or worded in a way to preclude parsing by pedantic assholes? No?
Hmmmm.

> But IMO, inflicting "the least effect on anyone else's travel" and/or
> "staying out of everyone else's way" would also have to include
> operating within the SL.

No. It wouldn't. If I drove at the speed limit on the highways around
here, I would interact with a very large amount more traffic than going
at or slightly above the "flow" speed. In addition, by keeping space
around me at all times (or trying to), I allow myself room to manoeuver
in the case that some other driver is not paying as much attention.

If I went the limit, I would be literally passed by every other car and
truck on the highway, until I got to the mountain passes.

Going the speed limit on the highways here is the definition of
"getting in everyone elses' way."

In town or in the neigborhoods is a completely different story.

>
> Another thing to consider, IME, is conflicting with and delaying
> traffic traveling in the other directions.

On a divided highway? Give me a break.

> I think the widepsread
> belief in r.a.d. is that if you are the fastest driver within your
> sphere of influence you are staying out of everyone else's way and not
> delaying anyone, and I disagree.

Without one piece of supporting evidence. Explain how keeping right
except to pass delays anyone, ever.

> I think that so many drivers exceeding the SL are causing all sorts of
> conflicts and delays they never consider, such as delaying another
> driver pulling into their path, or causing another driver to miss a
> light cycle, or delaying another driver's L turn, bunching up vehicles
> on the freeway, exits, etc., because they wouldn't be within x distance
> of traffic they might affect had they not exceeded the SL.

Sophistry that has no proof, nor any shred of reason behind it. If
I'm exceeding the limit on a limited-access highway, and interact with
three cars going in my direction (passing them on the left.) and one
car in the opposite direction (I just happen to be coming up on the car
turning across the highway), I have interacted with 3 cars, holding up
one. Who, BTW, might have been speeding also, or who may have had to
wait for some other car anyway.

Contrast this with going the SL. The faster cars behind will have to
interact with me, getting held up or not as other traffic may or may
not be present. Some may get held up, but ALL with had to do
*something* to avoid me.

> "Staying out of everyone else's way" or having "the least effect on
> anyone else's travel" and considering "everyone" and "anyone" to be
> always traveling in the same direction and always to the rear is a
> pretty simple minded POV, IMO.

You're the only one making that ASSumption. I sure didn't, and it
wasn't even implied by Scott's Golden Rule of Driving. Or, you are
attempting to create a strawman.

> > Of course, this is not the same thing as have NO effect on other
> > peoples' travel. Which, of course, is what you meant to ask.
>
> Duh. I didn't originate the phrase "the least effect on anyone else's
> travel", you nitwit. Try to guess who I was quoting... and what he
> meant.

No, you were just trying to recast it in a strawman attempt. LOL.

> > Get used to the fact that
> > there are many smarter people than you who surf the 'net.
>
> LOL! Of course, but I don't think you should consider that list
> includes you.

It's obvious to everyone reading this exchange (except you, of course)
which of us bring more to the table in the way of brains. BTW, hat
size doesn't correlate to reasoning capacity.

> At some point a man needs to evaluate what his mom told
> him about his looks and his intelligence.

Since my mom died when I was 14 months old, that's not really an issue
for me. Maybe you should consider taking your own advice...

E.P.

Billzz wrote:
> "Scott en Aztlán" > wrote in message
> ...
>> Bernd Felsche > said in
>> rec.autos.driving:
>>
>>>>>>>>> A freeway is "full" when all lanes are at 1800 vehicles/hour.
>>>>>>>> Upon what assumptions is this number based?
>>>>>>> Minimum "safe" following interval of 2 seconds.
>>>>>> So if everyone is in a traffic jam and moving at 0 MPH the road is not
>>>>>> "full?"
>>>>> It's then ZERO vehicles/hour. That's the same as when there are no
>>>>> vehicles using the freeway.
>>>> Obviously not. In one case there are NO cars on the road; in the other
>>>> there are THOUSANDS.
>>>> Let me phrase my question another way: what is the formula you used to
>>>> arrive at the 1800 vehicles/hour figure you tossed out earlier? What
>>>> variables are part of the formula? Hint: vehicle velocity is one of
>>>> the terms.
>>> This is independent of vehicle speed.
>> That's ridiculous.
>>
>> Suppose you had a bunch of cars, each exactly 20 feet long. If you
>> parked them in one lane, bumper-to-bumper, you could fit 5280/20 = 264
>> of them into one mile. However, since they are parked, the number of
>> vehicles passing any given reference point is 0 vehicles/hour.
>>
>> Now let's increase the speed of the cars to 1 MPH. If they remain
>> bumper-to-bumper, those 264 vehicles will pass your reference point in
>> exactly 1 hour. Add in a 2-second following distance between them
>> (~2.93 feet at 1 MPH) and the maximum you can expect is 5280/22.93 =
>> ~230 vehicles/hour.
>>
>> Now let's double their speed to 2 MPH. Following distance increases to
>> 5.87 feet, and the maximum number of vehicles that can pass a given
>> spot in the road increases to 2 * 5280 / 25.87 = ~408 vehicles/hour.
>>
>> Clearly the number of cars which can potentially pass any given fixed
>> point during one hour varies directly with vehicle speed as well as
>> vehicle length (and perhaps other things I haven't thought of). It
>> seems to me that the actual formula ought to look something like this:
>>
>> lane capacity (vehicles/hour) = vehicle speed (miles/hour) * 5280
>> (feet/mile) / (vehicle length in feet + following distance in feet)
>>
>> By holding the car length constant at 20 feet, plugging and chugging
>> gets up the following maxima:
>>
>> 1070 v/h at 10 MPH
>> 1342 v/h at 20 MPH
>> 1466 v/h at 30 MPH
>> 1537 v/h at 40 MPH
>> 1584 v/h at 50 MPH
>> 1616 v/h at 60 MPH
>> 1640 v/h at 70 MPH
>> 1658 v/h at 80 MPH
>> 1673 v/h at 90 MPH
>> 1685 v/h at 100 MPH
>>
>> Hmm... Seems to be approaching some sort of asymptotic limit...
>>
>>>> Understood. I'm just asking for the non-dumbed-down version.
>>> Ahhh.. you're trying to be stupid. You're very good at it.
>> Yeah, I guess so. So since you're so smart, suppose you tell us what
>> combination of vehicle length and vehicle speed will result in a total
>> of 1800 vehicles/hour passing by a given refernce point?
>
> I was just passsing by, and just noticed this. Are the figures above for
> one lane? A freeway would be two or more lanes - I think.


Bernd did say "a freeway is full when all lanes are at 1800 vehicles per
hour". It's at the top of this post actually.

Ben

On Wed, 06 Sep 2006 07:17:16 -0700, Scott en Aztlán
> wrote:

>Bernd Felsche > said in
>rec.autos.driving:
>
>>>>>>>>A freeway is "full" when all lanes are at 1800 vehicles/hour.
>>
>>>>>>>Upon what assumptions is this number based?
>>
>>>>>>Minimum "safe" following interval of 2 seconds.
>>
>>>>>So if everyone is in a traffic jam and moving at 0 MPH the road is not
>>>>>"full?"
>>
>>>>It's then ZERO vehicles/hour. That's the same as when there are no
>>>>vehicles using the freeway.
>>
>>>Obviously not. In one case there are NO cars on the road; in the other
>>>there are THOUSANDS.
>>
>>>Let me phrase my question another way: what is the formula you used to
>>>arrive at the 1800 vehicles/hour figure you tossed out earlier? What
>>>variables are part of the formula? Hint: vehicle velocity is one of
>>>the terms.
>>
>>This is independent of vehicle speed.
>
>That's ridiculous.
>
>Suppose you had a bunch of cars, each exactly 20 feet long. If you
>parked them in one lane, bumper-to-bumper, you could fit 5280/20 = 264
>of them into one mile. However, since they are parked, the number of
>vehicles passing any given reference point is 0 vehicles/hour.
>
>Now let's increase the speed of the cars to 1 MPH. If they remain
>bumper-to-bumper, those 264 vehicles will pass your reference point in
>exactly 1 hour. Add in a 2-second following distance between them
>(~2.93 feet at 1 MPH) and the maximum you can expect is 5280/22.93 =
>~230 vehicles/hour.
>
>Now let's double their speed to 2 MPH. Following distance increases to
>5.87 feet, and the maximum number of vehicles that can pass a given
>spot in the road increases to 2 * 5280 / 25.87 = ~408 vehicles/hour.
>
>Clearly the number of cars which can potentially pass any given fixed
>point during one hour varies directly with vehicle speed as well as
>vehicle length (and perhaps other things I haven't thought of). It
>seems to me that the actual formula ought to look something like this:
>
>lane capacity (vehicles/hour) = vehicle speed (miles/hour) * 5280
>(feet/mile) / (vehicle length in feet + following distance in feet)
>
>By holding the car length constant at 20 feet, plugging and chugging
>gets up the following maxima:
>
>1070 v/h at 10 MPH
>1342 v/h at 20 MPH
>1466 v/h at 30 MPH
>1537 v/h at 40 MPH
>1584 v/h at 50 MPH
>1616 v/h at 60 MPH
>1640 v/h at 70 MPH
>1658 v/h at 80 MPH
>1673 v/h at 90 MPH
>1685 v/h at 100 MPH
>
>Hmm... Seems to be approaching some sort of asymptotic limit...
>
>>>Understood. I'm just asking for the non-dumbed-down version.
>>
>>Ahhh.. you're trying to be stupid. You're very good at it.
>
>Yeah, I guess so. So since you're so smart, suppose you tell us what
>combination of vehicle length and vehicle speed will result in a total
>of 1800 vehicles/hour passing by a given refernce point?

Its unlikely that there is any strict math formula. Because cars are
driven by humans, which introduces randomness, there is a point at
which smooth flow breaks down due to the number of vehicles and then
any formula (other then an empirically derived one) goes out the
window. I believe I read once that there are two "maximums" so to
speak, a volume at which you can go fast and still get a lot of cars
thru, and a bigger volume where you get even more cars thru but at a
much lower speed, something like 40 mph. It's likely that the 1800 is
the empirical result for max volume, which in one sense is regardless
of speed, but actually means, at whatever speed it works out to be on
a given road.