Two way study graphic now available
Richard Aleksander
newsgroup, who broadly and without documentation, asserted,
>For pedestrians, NOTHING IS SAFER THAN ONE WAY TRAFFIC. You only have to
>look one direction for cars!
I wrote,
A new study disproving this statement by Lic. PE Walter Kulash:
http://www.glatting.com/html/links.html finds there's 16 times more
possibilities for ped-auto conflicts in one-way than two-way operations.
In one way scenarios, the operation of every intersection is different from
the previous one...signs are sometimes missing...and pedestrians don't know
what to expect...particularly visitors.
Roberta and Craig Becker wrote in message <3587f...@feed1.realtime.net>...
>This is rather a counter-intuitive conclusion. I'd like to
>read the study, can you provide a more precise link to it?
>The given URL leads to a Links page--how do I get to the
>actual study by this Kulash fellow?
I have a printed explanation and a color poster depicting the two scenarios
for ped auto conflict in two way, versus 16 for ped auto conflicts in one
way operations.
It's 390kb, scanned by Terry Nathan, and ready to post or send to you.
Would you a.g.-ers prefer if I posted the graphic here, or shall I e-mail it
separately to those interested in examining it for themselves?
Here's the text that accompanies it:
We are enclosing an analysis of the impact of one-way streets on pedestrian
crossings. the analysis was conducted for the City of New Haven, but it is
equally applicable to any combination of one-way streets in any location.
The conventional wisdom has always assumed that one-way streets were safer
and more comfortable for pedestrians to cross than two-way streets. The
rationale was that traffic moves only in one direction on a one-way street,
while it moves in two directions on the two-way streets. Superficially, it
would seem that crossing the single direction of traffic on a one-way street
is always preferable to crossing a two- way street.
As is often the case, conventional wisdom is wrong. In fact, crossing a
one-way street presents greater difficulties to the pedestrian than crossing
a two way street. The explanation lies in the greater number of different
vehicle/pedestrian conflict sequences (hereinafter "conflict sequences")
that are encountered in crossing the one-way street. Any given conflict
sequence consists of: (1) the kind of turning movement that the vehicle is
engaged in, (2_ the direction (left to right or vice versa) in which the
vehicle path intersects with the pedestrians and (3) the location of the
vehicle with respect to the pedestrian's field of view, at the beginning of
the vehicle movement.
There are only two possible sequences (sequences #1 and #2 in diagram that a
pedestrian can encounter in crossing a two way street. Regardless of what
leg of the intersection they cross, they will never encounter any other than
these two conflict sequences. Further, these two conflict sequences are
closely related, essentially the "mirror image" of each other.
On one-way streets, by contrast, there are sixteen different conflict
sequences that a pedestrian can encounter, depending upon which leg of the
intersection. Further these sequences vary widely in their component parts.
For example, some sequences have only a single conflict, while others have
two or even three. further, the sequences involve a wide variety of
direction of vehicle flow and pedestrian view of vehicle.
The conventional view of the safety of one-way street crossing usually
focuses on crossing the up stream leg of the intersection, in which only a
single turning movement is encounter (sequence #11 and #12 in the diagram).
However this situation comprises but two of the sixteen possible conflict
sequences. The complexity and variety of the other fourteen are typically
overlooked when discussing the merits of one-way streets.
We should also remember that a one-way street system always has a greater
magnitude of vehicle turning movements compared to a two-way system/. Any
turning movement, regardless of street configuration as one-way or two way,
creates exactly the same potential for vehicle/pedestrian conflict; namely
one legally turning vehicle crossing the path of one legally crossing
pedestrian. Thus, aside from the complexity of conflict sequences, there
are simply more (typically
30-40%) vehicle pedestrian conflicts with an one-way street than a two way
street.
We are combining this analysis with several other points in a technical
paper, and will send you a draft when presentable.
Walter M. Kulash/pae
Enclosure>
Clayton Colwell
: Roberta and Craig Becker wrote in message <3587f...@feed1.realtime.net>...
: >This is rather a counter-intuitive conclusion. I'd like to
: >read the study, can you provide a more precise link to it?
: >The given URL leads to a Links page--how do I get to the
: >actual study by this Kulash fellow?
: I have a printed explanation and a color poster depicting the two scenarios
: for ped auto conflict in two way, versus 16 for ped auto conflicts in one
: way operations.
: It's 390kb, scanned by Terry Nathan, and ready to post or send to you.
: Would you a.g.-ers prefer if I posted the graphic here, or shall I e-mail it
: separately to those interested in examining it for themselves?
DON'T POST A BINARY!
Sorry for shouting. No, I think it best that you either get
the graphic up on someone's webpage or e-mail it to interested
folks.
(I'd like a copy, if you'd uuencode the graphic first.)
****** Clay Colwell (aka StealthSmurf) ********** er...@bga.com ******
* "In the future, we will recognize software crashes as technologically *
* mandated ergonomic rest breaks - and we will pay extra for them." *
* -- Crazy Uncle Joe Hannibal *
Mike Dahmus
<r.alek...@worldnet.att.net> wrote:
>About three weeks ago, the writer responded to someone in the local
>newsgroup, who broadly and without documentation, asserted,
>
>>For pedestrians, NOTHING IS SAFER THAN ONE WAY TRAFFIC. You only have to
>>look one direction for cars!
>
>I wrote,
>
>A new study disproving this statement by Lic. PE Walter Kulash:
>http://www.glatting.com/html/links.html finds there's 16 times more
>possibilities for ped-auto conflicts in one-way than two-way operations.
Good start. Included web link.
>In one way scenarios, the operation of every intersection is different from
>the previous one...signs are sometimes missing...and pedestrians don't know
>what to expect...particularly visitors.
Whoa, hold on a minute there. If we redefine each other's position
this way I could say that two-way streets are deathtraps because
sometimes the yellow line wears out and cars slam into each other
head-on. Plus there's all those British people who don't know which
side of the street they're supposed to drive on.
If you want to assume negligence, go ahead - but it does nothing to
prove your point about one-way streets vs. two-way streets.
>The conventional view of the safety of one-way street crossing usually
>focuses on crossing the up stream leg of the intersection, in which only a
>single turning movement is encounter (sequence #11 and #12 in the diagram).
>However this situation comprises but two of the sixteen possible conflict
>sequences. The complexity and variety of the other fourteen are typically
>overlooked when discussing the merits of one-way streets.
This is creative, especially since one of the benefits of the one-way
system is that you can CHOOSE to cross in the "up stream leg" two
times to avoid crossing at a "down stream" leg.
Pretty much what I expected, though - the author of the study made a
bunch of assumptions about bad pedestrian behavior, and then applied
them ONLY to the one-way side, not to the two-way side. (He didn't
talk about pedestrians not looking for turning traffic from the other
side of a median, for example).
Mike Dahmus mdahmus at I O DOT COM
http://www.io.com/~mdahmus/
"No one likes a pedantic smartarse..."