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2008-04-10

Simulating Traffic in 3D Cities: Agents, Shockwaves and Grids


Simulating traffic is a science in itself with each car acting as an agent that is aware of its surroundings. It is notoriously difficult to create convincing traffic flow in 3D packages without input from specialist simulations and as such its a good challenge for our recent explorations of using agents in 3D Max to populate city models.

New Scientist highlighted the 'Shockwave' theory of traffic simulation this month with an article on how a team of Japanese researchers has recreated the phenomenon on a test-track for the first time.

The mathematical theory behind these so-called "shockwave" jams was developed more than 15 years ago using models that show jams appear from nowhere on roads carrying their maximum capacity of free-flowing traffic – typically triggered by a single driver slowing down.



With simple agents in 3D Max our first movie interestingly produces similar results:



If you then set up 'three teams' linked to a network with behaviour based on varying speed and avoidance calculations you can create a basic traffic flow simulation.



As we have said, these are first steps and there are some obvious issues to iron out with the aim to import the traffic flow into scenes such as our 'Greeble City Tutorial' model illustrated below:

Interestingly the work going on just to our left using the Crysis game engine for traffic flow is proceeding at a notable rate, we should have a movie of this tomorrow...

Read more about the Shockwave Theory and NetLogo.

2 comments:

  1. Wondering if you've looked at packages like VISSIM that are specifically design ed to do this sort of traffic modeling, or are you trying to work completely within visualization packages?

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  2. Traffic that grinds to a halt and then restarts for no apparent reason is one of the biggest causes of frustration for drivers. Now a team of Japanese researchers has recreated the phenomenon on a test-track for the first time.

    The mathematical theory behind these so-called "shockwave" jams was developed more than 15 years ago using models that show jams appear from nowhere on roads carrying their maximum capacity of free-flowing traffic – typically triggered by a single driver slowing down.

    After that first vehicle brakes, the driver behind must also slow, and a shockwave jam of bunching cars appears, travelling backwards through the traffic.

    The theory has frequently been modelled in computer simulations, and seems to fit with observations of real traffic, but has never been recreated experimentally until now.

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