In class, we discussed the existence of Nash equilibria in Traffic Networks, where the individual travelers hope to pick the route from origin to destination with the lowest travel time. Travel time, however, is not a static factor, as increased congestion on a road results in slower driving speeds and therefore longer travel times. If we consider these equilibria in real-world networks, the assumption must be made that all of the travelers have knowledge about congestion, weather, construction, or any other factors that would effect travel time on all of their possible routes.
In reality, this is obviously not the case. Information regarding traffic conditions on major roads can be heard by word of mouth, on radio stations, or even looked up on websites such as Google Maps and SmarTraveler prior to departure, but conditions often change quickly. With the introduction and increasing popularity of in-vehicle GPS navigation systems, the opportunity to deliver current, accurate traffic conditions is increased even further. In the world of Traffic Engineering, these methods are all Advanced Traffic Information Systems (ATIS), a type of Intelligent Transportation System.
As ATIS become more popular and more common, the question is raised: are benefits encountered by all users, or is there some point of saturation when an additional ATIS user does not experience any benefit. Obviously, if you are the only driver who knows that one road is congestion free, you will choose that route. If every driver has access to the same information, however, nobody has a clear advantage. The following article, “Route Choice, Network Traffic, and Intelligent Transportation Systems” by Randall Hall from USC provides an overview of a number of simulation studies that attempt to answer that question. Hall concludes that providing accurate information will never decrease performance of the network (as others have suggested), but he warns that the main function of ATIS should be to provide confidence for the drivers, and to steer traffic away from dis-equilibrium situations such as traffic jams.
Hall, R.W.
Route choice and advanced traveler information systems on a capacitated and dynamic network
Transportation Research Part C (Emerging Technologies)
Vol. 4, 5, 1996, p. 289
Route choice and advanced traveler information systems on a capacitated and dynamic network
[Must log into Engineering Village as Cornell student to view full text]
Information about ITS/ATIS:
* You can follow any responses to this entry through the RSS 2.0 feed.