Ventana software support forum

Posted: **Sat Apr 08, 2000 10:57 am**

Hi Arif,

I think you should find some information in the field of microscopic
trffic simulation, where they want to make real time road traffic forecast
e.g. for cities.
I found a website at a German university, where a model for this purpose is
developed with cellular automata. On this site there are also links to similar
pages: http://www.traffic.uni-duisburg.de
esearch.html

I developed an accident model with system dynamics which shows the development
of accident rates as a part of a European model for transport policy
assessment.
But this model is not working on the basis of real time individual driver
behaviour but
instead on macroscopic characteristics like speed-limit, seat-belt usage,
blood alcohol
limit for different road types and regions. You should find some
information on it in
the deliverable 3, which you can download from our website
http://www.uni-karlsruhe.de/ASTRA/

Nevertheless, from your description I would assume that the microscopic
simulation fits better to your purpose.

Best regards

Wolfgang
### ------------------------------------------------------ ###
Wolfgang Schade

University of Karlsruhe
Institute for Economic Policy Research (IWW)
Kollegium am Schloß, Bau IV
76128 Karlsruhe, Germany

Email: wolfgang.schade@iww.uni-karlsruhe.de
Phone: +49 (0) 721 608-4371 Fax: +49 (0) 721 34613
### ------------------------------------------------------ ###

Posted: **Mon May 29, 2000 10:21 am**

Hi everyone,

Im looking for references about simulation of road accident, any example of
simulation model to replicate the driver behavior, the road accident
mechanism, any simulation model that describe how actually road accident
happen, any simulation program that allow to build a model of road accident
mechanism. The background of this query is described in the following.

I am working in the area of “Simulation of road accidents” for my
Ph.D. thesis at University of Waterloo, Canada. The objective of research is
to find the causes of road accident and cost effective counter measures that
should be implemented to reduce the accident rate. The output of research
would be useful to evaluate the technologies being implemented for road
safety. Earlier we thought to use Fault Tree Analysis for our research,
however, later on we figured out we are doing something related to
simulation not exactly Fault Tree Analysis. We finally decided to use
simulation. I am familiar with System Dynamics; I learnt SD at Asian
Institute of Technology during my Master and developed a SD model of
Railways. Prof. Khalid Saeed supervised this work, while he was at AIT. I
wished I could proceed with SD, unfortunately no one knows about SD at
University ofWaterloo to support my research. Your guidance about my
research is solicited. In road accident, for example for rear end crash
assuming that two successive vehicles are moving in a same lane. The
following vehicle hit the leading vehicle. I want to simulate the mental
model of following vehicle driver, how he/she reacts when leading vehicle
decelerates. Suppose two time windows one is for time available and the
other is time required to action. The time available is some kind of
standard time or safety margin time headway, could be function of relative
speed of both vehicles, initial distance between vehicles, traffic volume,
density. While time required for following vehicle driver to take action
could be function of driver perception reaction, vision, road geometry,
weather condition, road surface condition etc. When leading vehicle slow
down, following will perceive the target and act (apply brakes) to avoid the
crash. Whenever, the time required window is higher than time available,
there will be crash.

I would appreciate your guidance for my research.

Thanks,

Arif Mehmood
Doctoral Student (Transportation Planning)
University of Waterloo, Canada
113-161 University Avenue West,
Waterloo, Ontario, Canada
N2L3E5
Tel (519) 886 8996
Email:amehmood@uwaterloo.ca

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Posted: **Tue May 30, 2000 8:03 am**

Arif;
Hope you will have some replies related to your inquiry. I would recommend
that you review publications and work in the area of disaster management
(there were number of submissions to this group on this topic). I am sure
that you will be able to learn and implement these ideas to your problem
domain.
And one more comment. I think that you made a judgment call that was not
fair to our colleagues at the University of Waterloo. I am not from
Waterloo but know a number of people at the Department of Systems
Engineering who have interest and do work in system dynamics.
CheersSlobodan P. Simonovic
Professor and Director
Natural Resources Institute
The University of Manitoba
Winnipeg, Canada, R3T 2N2
phone (204)474-8375; fax (204)261-0038
e-mail slobodan_simonovic@umanitoba.ca
web site http://www.fids.umanitoba.ca/~simon

Posted: **Wed May 31, 2000 4:29 pm**

Hi Arif:

One stream-of-consciousness response that comes to mind upon reading your
problem statement below is that the structure of a simple traffic system in
which one driver is following another (and even better, if several drivers
are following one another in line) is similar (at least at first pass) to
the structure of the beer game -- i.e., a production-distribution system or
supply chain. Alan Graham makes this point (although in a different
context) in his Ph.D. thesis (see pages 161-174). Of course, instead of
ordering/shipping beer to fill/drain their stocks of beer inventory,
drivers "order" units of position by (accelerating/decelerating) to change
their "stocks" of velocity which, in turn, over time, change their stocks
of position relative to the cars in front of them. As in the beer game,
good drivers must be careful to take their effective inventory of beer
(relative position), beer already ordered and in the pipeline (velocity
[speed]), and new order stream (the acceleration/deceleration of the driver
in front of them) into account when placing orders to their supplier
(stepping on the gas or brake).

Anyway -- its a place to start.

Peace.

Mike Radzicki
WPI
From: "Michael J. Radzicki, Ph.D." <mjradz@WPI.EDU>

Posted: **Tue Jun 06, 2000 11:19 am**

Rather than create an equation for "safe following distance" which depends
on many factors, primarily the speed of the vehicles, perhaps you can
simplify by assuming that (at any speed) the following vehicle must be (a
constant) three seconds behind the one in front. I know that this is a
guideline given to students in driving class.

I also recall (although it was a long time ago) that normal (unimpaired by
poor visibility, alchohol or drug use, etc.) reaction time to seeing the
brake lights of the vehicle ahead of you and stepping on your brakes is
about 2/5 of a second. Ive noticed, however, in my own driving that I no
longer automatically step on my brakes when I see brake lights ahead of
me -- I take a short time to assess the situation. And I am reluctant, in
almost any situation, to use maximum braking (for fear of throwing
passengers around inside my car and for fear that Ill lose control in a
skid.) This is not necessarily the best policy but I wonder if others do
the same. If these considerations factor in, the "normal" reaction time
should increase -- and so should the "safe following time."

Im aware that there are significant differences in braking ability of
vehicles -- with heavier vehicles (such as SUVs) typically unable to stop
as quickly as light ones. In addition to the extra damage a heavier vehicle
will do to my car, this braking factor makes me very, very nervous when an
SUV is tailgating me!!

Of course, you also have to take into account how distracted the driver of
the following vehicle is -- putting on lipstick, talking on a cellular
phone, changing the radio settings, turning the head to talk with someone in
the back seat, etc.

For what its worth ...
From: "John Gunkler" <jgunkler@sprintmail.com>