|MadSci Network: Engineering|
The primary cause of the "traffic jam" may be attributed to cautious drivers. These drivers pass the stalled vehicle at a reduced speed in hopes of avoiding hitting the stalled car or a person and see for themselves the extent of the situation (rubbernecking). And when one driver slows down noticeably, others will follow in hopes to avoid the situation as well (an accident, flat tire, stalled car, or even a police officer). This chain reaction then collects in volume as more individuals are forced to slow down and maybe even stop due to other drivers slowing down, changing lanes, etc. And once you passed the situation, the road is wide open and traffic flow can resume to normal speed. Now modeling. At first, I would have said "no, it would be quite difficult to simulate uncertainties such as accidents and stalls." However, I did a little homework and found that several universities and traffic institutes are working on improving traffic models and computer codes to contain "conflicts". These "conflicts" range from pedestrian traffic to vehicle accidents. Even though the situation you encountered was a "stall" one may take the condition to be a "conflict" as well. I guess no matter how you would look at it, at some point in time a vehicle will break down or have an accident within a given population and flow stream of vehicles. This would give you a likely probability for encountering a stall or accident ("conflict") which could then be incorporated within a traffic flow model or computer code and be accounted for. In addition, many traffic codes and models include a mathematical model for the "stop and go" wave phenomenon. I wish I knew more on the subject but I have included some web sites I located that have additional information about Traffic Models and some specifically that include information about model and codes containing "conflicts": http://tti.tamu.edu/research/operations/ http://www.unb.ca/web/transpo/mynet/mty80.htm http://www.unb.ca/web/transpo/mynet/mtu3.htm http://rcswww.urz.tu-dresden.de/~helbing/inside.html http://www.hut.fi/Units/Transportation/Research/ http://www.unb.ca/web/transpo/ http://www.swov.nl/en/actueel/swovschrift/Traffic_models,_inner_areas_and_r oad_danger.html And these traffic phenomenon are not unique to the United States. Some of the above web sites are from European countries. And unfortunately, accidents, stalls, and other traffic situations will always occur at some point in time inevitably creating a traffic jam. It's all about mechanical unreliability (the breakdown) and human nature (slowing down [a good thing] and rubbernecking [a not so good thing]). Hope this will help answer your questions.
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