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Traffic Simulator

traffic-simulation.de

51–60 of 143 posts

Re: Traffic Simulator

#51
Cities Skylines is very nice for such traffic simulations.

https://www.youtube.com/watch?v=yITr127KZtQ (https://news.ycombinator.com/item?id=17182008) (https://www.reddit.com/r/CitiesSkylines/comments/7h6zr0/traf...)

https://www.youtube.com/c/BiffaPlaysIndie/search?query=lane+...

This is frequently posted here on HN. E.g. https://news.ycombinator.com/item?id=25632642.

Re: Traffic Simulator

#52

Earlier quoted context omitted.

The other thing that really seems to make the biggest difference (in combination with better acceleration) is following distance, which is another thing that presumably gets less important with autonomous cars because you don't really have to account for a relatively slow reaction time or poor braking. The observation on acceleration does make me wonder whether teaching proper merging etiquette better (reach freeway…

How do autonomous cars deal with cheap or worn tyres? Is there still a lot of allowance for braking distance?

A burnout at the beginning of every drive cycle would do wonders for calibration.

Re: Traffic Simulator

#54
post #45

The more lanes you add, the more cars you get. Adding more lanes doesn't solve traffic issues. https://en.wikipedia.org/wiki/Induced_demand#Induced_traffic...

"Induced demand" is just a backhanded way of complaining that more people can be served by expansion of a particular piece of infrastructure that you don't like. Nobody ever complains about induced demand on the subway from more frequent service causing more people to decide that's the best option for them.

Rush hour is like pouring a 5gal bucket into a sink. You can't reasonably handle that all at once will have some water in it until it all makes its way through the pipe. But you have to be insane to use that as an argument against making the pipe bigger. Increasing the max capacity of the pipe (so more lanes, in the case of highways) means that it can have normal flow before it starts backing up. The "induces" demand because at the margins some people who were voluntarily changing their usage times to avoid the peak hours will commute at peak hours.

I am intentionally trying to use generic language here because this isn't a unique phenomenon to highways.

Re: Traffic Simulator

#56
I love these little simulators because while they purport to show that slower more polite driving is more efficient, more often than not they show the exact opposite. Want to shove the most cars through per hour? Remove the speed limit. Accelerate and brake like every intersection is a drag race. Leave absolutely no distance between cars. And dump any notion of polite lane changes. NASCAR was right: Minimize unused pavement. The most efficient way to move large numbers of cars down a road is at 200mph with only inches between each car.

Re: Traffic Simulator

#57
post #35

I've always wanted to program something like this. What are good references to simulation programming to handle this kind of use case?

I was also looking to learn more about this. Discrete Event Simulation books may be of some help.

Re: Traffic Simulator

#58
post #23

On the ring map, with default settings, just stopping traffic with the traffic light for a second produces the dreaded rubber-band effect propagating forever around the circle. Fun simulator!

That behaviour is mesmerising to observe in the simulation.

Re: Traffic Simulator

#59

Perhaps these questions are appropriate for this post. I'm beginning to delve into this space and I've not managed to get any satisfactory answers to these questions, despite my month(s) long search. 1) How does one build a traffic (i.e state-space system), forgetting the visualization aspect of things ? Just generating sparse matrices, and adding elements to interact (add/subtract) from these matrices would be a gre…

1) There are different choices you can make about simulating individual agents or aggregate flows along roads. Assuming you're interested in the former, you can advance the simulation in discrete time-steps using approaches like the intelligent driver model mentioned in another thread. Chapter 4 of https://apps.cs.utexas.edu/tech_reports/reports/tr/TR-2157.p... is a different approach to the discrete time system that tries to handle complications that come up when applying to OpenStreetMap, like having a vehicle cross multiple roads and intersections in a single 0.1 second timestep, due to really short roads. If you're willing to throw away detailed movement (including acceleration and lane-changing), you can try a discrete-event approach, where you say "this vehicle enters one end of a road at time t, don't calculate anything for it until t + best_case_time_to_cross". https://dabreegster.github.io/abstreet/trafficsim/index.html has some ideas there.

2) Another option with much less detailed traffic simulation, but much more UI focus, is abstreet.org

Re: Traffic Simulator

#60
post #16

Things like this are cool. What I would be curious to see though, rather than setting global parameters (i.e., politeness), would be to have each agent have its own politeness score (as well as other attributes). Models like the one linked to here work as if each agent is a particle, rather than autonomous decision-maker adapting to their circumstances locked in long-term, iterated games with other anonymous drivers.…

> Some places the drivers are so polite to the point it really makes things dangerous

I live in a small town that has extra polite drivers. It was really confusing for a while. Eventually I realized that it was a practical response to the overall street layout, with a limited number of main streets, and different areas of town not being well connected. Stopping to let others cross improves the overall traffic flow - if no one did it, traffic would just be backed up for miles.

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