Simulation/Output/Lane- or Edge-based Traffic Measures

Values within this output describe the situation within the network in terms of traffic science by giving macroscopic values such as the mean vehicle speed, the mean density, etc. This output can be generated either for lanes, or for edges.

In the following, it is described how both outputs are generated and which values they contain. Then, the meanings of the values are given as well as a description of intervals. At last, some additional possibilities to constraint the outputs are given.

Meandata Definition
An edge-based state dump is defined within an additional file as following: " file=""/>

For a lane based dump simply write: " file=""/>

For additional attributes see the table below.

Edge-Based Network States
For edge-based state dumps, the output file will look like the following: " end="" id=""> " sampledSeconds="" \ traveltime="" \ density="" occupancy="" \ waitingTime="" speed="" \ departed="" arrived="" \ entered="<ENTERED_VEH_NUMBER>" left="<LEFT_VEH_NUMBER>" \ laneChangedFrom="NUMBER_OF_LANE_LEAVERS" laneChangedTO="NUMBER_OF_LANE_ENTERER"/>

... more edges ...

... further intervals ...

Please note, that in contrary to the example above, for each edge, all values are reported in one line.

Lane-Based Network States
The generated output looks like the following: <interval begin="<INTERVAL_BEGIN>" end="<INTERVAL_END>" id="<DETECTOR_ID>"> <edge id="<EDGE_ID>"> <lane id="<LANE_ID>" sampledSeconds="<COLLECTED_VEHICLE_SECONDS>" \ traveltime="<MEAN_TRAVEL_TIME>" \ density="<MEAN_DENSITY>" occupancy="<MEAN_OCCUPANCY>" \ waitingTime="<MEAN_WAITING_TIME>" speed="<MEAN_SPEED>" \ departed="<EMITTED_VEH_NUMBER>" arrived="<ARRIVED_VEH_NUMBER>" \ entered="<ENTERED_VEH_NUMBER>" left="<LEFT_VEH_NUMBER>" \ laneChangedFrom="NUMBER_OF_LANE_LEAVERS" laneChangedTo="NUMBER_OF_LANE_ENTERER"/>

... more lanes...

... more edges ...

... further intervals ...

Please note, that in contrary to the example above, for each lane, all values are reported in one line.

Value Descriptions
Both the edge-dump and the lane-dump are computing the values the same way: every vehicle move - even those with v=0 - is recorded and saved during the interval. After the interval has passed, these values are written into the file after being normalized. In the case of the edge-dump the values are not only normalized by the number of the collected vehicle moves and the length of the lane, but also by the number of lanes of the edge.

The meanings of the written values are given in the following table. Please note that in the case of edge meandata both laneChanged entries are equal to the total number of lane changes on the edge. Furthermore each lane change is counted separately, that means if one vehicle changes from lane 1 to lane 3 it will generate two lane change counts.

How to aggregate / derive further values
In order to aggregate the output for the same edge / lane over larger time periods the values which count vehicles have to be simply summed, density and occupancy can be simply averaged (if the interval lengths are equal) and speed should be a weighted average with sampledSeconds as weight. To aggregate the traveltime further, calculate the mean speed first and then divide edge/lane length by the speed.

Spatial aggregation (over multiple edges or lanes) is not as easy, especially if they are consecutive, because each vehicle generates data on each lane it is on, even if it is on multiple lanes. In the case of many short and fast moving vehicles the error is negligible but if you have long and slow vehicles you cannot aggregate as above.

The following measurements can be derived from the values given (period denotes the length of the aggregation interval):
 * Average number of vehicles on the edge (#) = sampledSeconds / period
 * Average traffic volume (#/h) = speed * density / 3.6
 * Traffic volume at the begin of the lane / edge (#/h) = 3600 * entered / period
 * Traffic volume at the end of the lane / edge (#/h) = 3600 * left / period
 * Total distance travelled (m) = speed * sampledSeconds