Hi Jakob, Ah great, I'll play around with sigma now then.
Regarding model braking, I've had a quick look, is this something in the vstop and vsafe methods, in the various cpp files in microsim/cfmodels? Any pointers for where to modify appreciated! Thanks Quoting Jakob Erdmann <namdre.s...@googlemail.com>: > Hello, > in the default car-following model (Krauss) there is no concept of > overbraking. Vehicles will always brake just hard enough to avoid a crash > (which probably is quite unrealistic). However, the Krausss model does have > congestian waves due to imperfect acceleration (parameter sigma > 0). You > should see a ripple of vehicles braking and due to the nature of imperfect > accelerations, this ripple should travel backwards and remain stable for > quite a while. > Since there is no overbraking the ripple will only get weaker instead of > stronger though. So if you want to have jams, you do have to make on > vehicle brake quite hard for a start. > regards, > Jakob > > PS: modifying existing car-following models is not terribly hard because > the part of the code is quite modular (there are already 9 models > implemented). Braking, harder than necessary would probably affect 1 line > of code and we might eventually add this feature now that I think about it). > > > 2014-02-15 <vb...@bath.ac.uk>: > >> Hi, >> >> I'm still having troubles with this, more in just creating a >> congestion wave / tailback in the first place. I've got a fairly busy >> looking flow on a motorway section, and set change lane mode to be >> only for strategic. The bulk of vehicles are standard passenger, which >> I've defined as: >> >> <vType id="normalVehicle" length="4.00" maxSpeed="40.00" >> guiShape="passenger" speedFactor="1.3" tau="2"/> >> >> And I'm inserting into fast lane at 40, next lane at 35, and other >> lane at 28. So, there's a mix of speeds, going quite fast. >> >> I have one vehicle selected which I have pre-planned to brake hard - >> for about 6 seconds it receives traci command to change speed to 1m/s, >> and then resumes to -1. Somewhat exagerated, but I was aiming for that >> sort of 'sudden braking causes a ripple of other vehicles braking' >> behaviour. >> >> The problem is.. the rest of the vehicles are just too good! It seems >> to me on the roads in the UK, if someone went from 40m/s to 1m/s there >> would be someone behind not paying attention, and either crash, or >> have to brake even harder.. >> >> So I'm wondering, is it just that I need to experiment with tau, max >> decel? Does sigma play some part? Reduce mingap? Or, is such behaviour >> just not possible with current model(s)? >> >> Thanks! >> >> Quoting "v.f.baines" <v.f.bai...@bath.ac.uk>: >> >> > Hi All, >> > >> > I'd like to implement some sort of repeatable congestion / traffic >> > wave scenario. I've created a decent volume of background traffic >> > using flows. If a vehicle now brakes suddenly or moves lanes >> > suddenly (typical cases I can think of which seem to start ripple >> > waves) should/would this impact the flow of the rest of the vehicles? >> > >> > I'm guessing this sort of scenario might have already been >> > implemented a few times so any pointers welcome. >> > >> > Also, any best practise for measuring the impact? At the moment ive >> > placed 5 detectors along the route which give a measure of vehicle >> > speed, so in congestion I'd expect this to drop. I guess time >> > between detections x detected speed would indicate vehicles gap >> > (assuming no lane change), small gap indicating congestion? >> > >> > Again, any suggestions welcome >> > >> > Thanks! >> > >> ------------------------------------------------------------------------------ >> > Managing the Performance of Cloud-Based Applications >> > Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. >> > Read the Whitepaper. >> > >> http://pubads.g.doubleclick.net/gampad/clk?id=121051231&iu=/4140/ostg.clktrk >> > _______________________________________________ >> > sumo-user mailing list >> > sumo-user@lists.sourceforge.net >> > https://lists.sourceforge.net/lists/listinfo/sumo-user >> >> >> >> >> >> ------------------------------------------------------------------------------ >> Android apps run on BlackBerry 10 >> Introducing the new BlackBerry 10.2.1 Runtime for Android apps. >> Now with support for Jelly Bean, Bluetooth, Mapview and more. >> Get your Android app in front of a whole new audience. 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