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Re: [sumo-dev] Understanding Wiedemann Model Implementation in SUMO

There is no concise documentation for these, sadly. I should probably put this in the wiki but right now the main wiki is down and we are using a backup at which is only updated once per day. So here is a short explanation:

The main functions of the car following model are  followSpeed and stopSpeed. These functions are used for determining the speed (obviously) but they are also called by the car-following models to evaluate safe gaps and prospective speeds on neighboring lanes.
The function finalizeSpeed is called exactly once per simulation step and vehicle. It ties together various constraints on vehicle speed resulting from car-following, planned stops and lane-change manoevure-planning. This function can also be used to update car-following model state (due to the fact that it is called exactly once per step).

I would be quite interested in seeing your implementation of Wiedemann and maybe improve our own.

2018-05-29 19:43 GMT+02:00 Umair Durrani <durraniu@xxxxxxxxxxx>:
Hi SUMO Team,

I want to understand how different components of car-following model (specifically Wiedemann model) and lane-changing model work together in SUMO. There are many functions, e.g. finalizeSpeed, followSpeed, etc. that are used in MSCFModel and MSCFModel_Wiedemann files. But it is not very clear how they work together.

Is there any documentation that you could provide that helps to understand how these components fit together?

I've also noticed that many equations in the Wiedemann.cpp file are different from the Wiedemann model publication:

Wiedemann, R. and Reiter, U., 1992. Microscopic traffic simulation: the simulation system MISSION, background and actual state. CEC Project ICARUS (V1052), Final Report, 2. 

I hope to implement the original model after understanding the current implementation. 

best regards,
Umair Durrani 
Ph.D. Candidate
Civil and Environmental Engineering

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