The reason for this output option is the possibility of SUMO to calculate emission for every simulation timestep. The calculated values for every vehicle will be recorded and can be used for a more sophisticated view on special parts of the network. The values depend on the selected emission models for the individual vehicles.
Instantiating within the Simulation#
To force SUMO to build a file that contains the emission output, extend your command line (or configuration) parameter by --emission-output <FILE>. <FILE> is the name of the file the output will be written to. Any other file with this name will be overwritten, the destination folder must exist.
By default, emission-output is enabled for all vehicles in the simulation with output in each simulation step. Using device assignment options or parameters (i.e. --device.emissions.probability 0.25) the set of vehicles which generate emission output can be reduced. The output period can be set by using option --device.emissions.period <TIME>.
The emission output is a xml-file containing the emission values for each time step for every vehicle. The produced XML File looks like this:
<emission-export> <timestep time="<TIME_STEP>"> <vehicle id="<VEHICLE_ID>" eclass="<VEHICLE_EMISSION_CLASS>" CO2="<VEHICLE_CO2>" CO="<VEHICLE_CO>" HC="<VEHICLE_HC>" NOx="<VEHICLE_NOX>" PMx="<VEHICLE_PMX>" fuel="<VEHICLE_FUEL>" electricity="<VEHICLE_ELECTRICITY>" noise="<VEHICLE_NOISE>" \ route="<VEHICLE_ROUTE>" type="<VEHICLE_TYPE>" waiting="<VEHICLE_WAITING>" lane="<VEHICLE_LANE>" \ pos="<VEHICLE_POS>" speed="<VEHICLE_SPEED>" angle="<VEHICLE_ANGLE>" x="<VEHICLE_POS_X>" y="<VEHICLE_POS_Y>"/> ... more vehicles ... </timestep> ... the next timestep ... </emission-export>
The meanings of the written values are given in the following table.
|time_step||(simulation) seconds||The time step described by the values within this timestep-element|
|id||id||The id of the vehicle|
|eclass||ID||The emission class of the vehicle|
|CO2||mg/s||The amount of CO2 emitted by the vehicle in the actual simulation step|
|CO||mg/s||The amount of CO emitted by the vehicle in the actual simulation step|
|HC||mg/s||The amount of HC emitted by the vehicle in the actual simulation step|
|NOx||mg/s||The amount of NOX emitted by the vehicle in the actual simulation step|
|PMx||mg/s||The amount of PMX emitted by the vehicle in the actual simulation step|
|fuel||ml/s||The amount of fuel used by the vehicle in the actual simulation step|
|electricity||Wh/s||The amount of electricity used by the vehicle in the actual simulation step|
|noise||dB||The noise emitted by the vehicle in the actual simulation step|
|route||id||The name of the route|
|type||id||The name of the vehicle type|
|waiting||seconds||The time the vehicle is waiting|
|lane||id||The name of the lane where the vehicle is moving|
|pos||meters||The vehicle position measured from the start of the current lane|
|speed||m/s||The speed of the vehicle|
|angle||degree||The angle of the vehicle|
|pos_x||---||The absolut X coordinate of the vehicle. The value depends on the given geographic projection.|
|pos_y||---||The absolut Y coordinate of the vehicle. The value depends on the given geographic projection.|
When running with sub-second resolution, the emissions written during every simulation step are extrapolated to those that would be generated in 1 second. Thus, care must be taken when computing sums over time.