Hi everyone, This is a little on the lengthy side of things, I hope you don't mind.
I'm currently working on a traffic simulation for a commercial project. The validity of the simulation is important, but in itself no metrics are required; it serves only as a visual aid to challenge the product's users when they complete various tasks. Prior to this moment, I have been working with a multi-lane simulation which did not include any off/on ramps or more complicated traffic systems. At this point, I moved to a "node based" model, which analyses geometry of a 3D mesh (using some helper information) to produce a graph of connected nodes. It has only been when writing the simulation for this graph that I realise how much more complicated the simulation must become. The list below indicates my new challenges: 1. Ramp merges affect the vehicles in the lane as well as those which are about to merge. Unlike lane merging, which is optional and only performed if the impact is minimal, vehicles on ramps prefer to maintain velocity, and vehicles behind them in the new lane will slow down somewhat. This changes the purist IDM model. 2. Routes require some level of planning in order to determine how far to the nearest vehicle. Whenever the vehicle ahead is on a separate lane (in the case of an on ramp, or a "decision" node where one lane can go either of two directions), we must investigate this and recall the path we took, so that our behavior corresponds with the vehicle we're following. We cannot consider artificially congesting routes unless we force a percentage of vehicles to follow those routes. 3. Road representation. I'm using polygons, but this creates its own challenge - using portals as midpoints along polygon edges for smooth lane changes and ramp exit/entrance. Long story short, being able to work out which vehicle is ahead of which is difficult when you're working with such flexible implementations. These are not the only problems I have or will continue to face, but I notice that SUMO is a mature (13 years?) simulation framework and I hoped to ask a few higher order questions. 1. How does SUMO handle ramps? Both in terms of the linear acceleration models of the vehicles involved and in the planning stage. 2. How does SUMO represent the vehicle in terms of its position on the road, and then convert to/from 2D cartesian coordinates? 3. Would it be possible to ask SUMO (with the Python interface) to spawn vehicles in specific positions at a user-defined interval, perhaps irregularly? I suspect that given other requirements of the simulation, I'd need to write my own Python bindings for certain things. 4. Is there any documentation on the overarching structure of the simulation design? I'm sure that I will have more questions, but any help at this stage would be great, kind regards, Angus Hollands. ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ sumo-user mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/sumo-user
