- All these attributes are factors and thus unitless - in the laDist computation, the value of LOOK_FORWARD is the time (10s) which is then scaled
Am So., 4. Juni 2023 um 04:24 Uhr schrieb Soumya Sharma via sumo-user < sumo-user@eclipse.org>: > Hello, > I am trying to conduct a sensitivity analysis of car-following and > lane-changing parameters in SUMO for hypothetical freeway segments (basic > and weaving). I tried changing headway values (car-following) and > lcStrategic values (lane-changing) for a basic segment. I used lcStrategic > values of 500, 1000, and 1500 for trucks in simulations (length = 15.25m). > My trucks are using the CACC model. > The two metrics I am interested in are the travel rates (secs/ mi) by > vehicle type and the number of lane changes per vehicle type. I found that > there was no change in travel rate and a number of lane changes when I > changed the value of lcStrategic to 500, 1000, and 1500. I don't understand > why there was no effect of changing the parameter values. > Next, I want to look into other parameters like "lcLookaheadLeft", > "lcAssertive" and "lcSpeedGain". > > *Question*: I would like to understand the units of the parameters > "lcStrategic" and "lcLookaheadLeft", "lcAssertive" and "lcSpeedGain". > > The SUMO documentation says: > > 1. lcStrategic: The eagerness for performing strategic lane changing. > Higher values result in earlier lane-changing. default: 1.0, range [0-inf), > -1 A value of 0 sets the lookahead-distance to 0 (vehicles can still > change at the end of their lane) whereas -1 disables strategic changing > completely. > 2. lcLookaheadLeft: Factor for configuring the strategic lookahead > distance when a change to the left is necessary (relative to right > lookahead). default: 2.0, range [0-inf) > 3. lcAssertive: Willingness to accept lower front and rear gaps on the > target lane. The required gap is divided by this value. default: 1, range: > positive reals > 4. lcSpeedGain: The eagerness for performing lane changing to gain > speed. Higher values result in more lane-changing. default: 1.0, range > [0-inf) > > These definitions don't mention any units explicitly, are they all > factors? i.e. unitless or are some of them in meters and some unitless? > > I was checking the code > <https://github.com/eclipse/sumo/blob/main/src/microsim/lcmodels/MSLCM_LC2013.cpp#L1850>for > LC2013 and found that look ahead distance (laDist) is being calculated as > follows: > > laDist = myLookAheadSpeed * LOOK_FORWARD * myStrategicParam * (right ? 1 : > myLookaheadLeft); > > > If this is how the look-ahead distance for a vehicle is calculated when > making lane-changing decisions, then both lcLookaheadLeft and lcStrategic > specified will be used to calculate laDist but I don't know what what the > units of any of these parameters are. For laDist to be in distance units, > speed would be multiplied by time here. > > Please share any information that is available as it would help me > understand my results better. > > Thanks, > Soumya. > _______________________________________________ > sumo-user mailing list > sumo-user@eclipse.org > To unsubscribe from this list, visit > https://www.eclipse.org/mailman/listinfo/sumo-user >
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