• Traffic Lights

SUMO offers some possibilities to save states of traffic lights during the simulation, a feature mainly used to evaluate adaptive traffic light algorithms. We will now describe these outputs.

TLS States#

Instantiating within the Simulation#

To enable writing tls state information you have to add the following definition into one of your additional-files:

<timedEvent type="SaveTLSStates" source="<TLS_ID>" dest="<OUTPUT_FILE>"/>

The attributes have herein the following meanings:

Generated Output#

The output looks like this:

<tlsStates>
   <tlsState time="<SIM_STEP>" id="<TLS_ID>" programID="<TLS_SUBID>" phase="<PHASE_INDEX>" state="<STATE>"/>
   ... further states ...
</tlsStates>

The state is saved in each simulation step. The state itself is coded as a list of the characters 'G', 'Y', and 'R', standing for "green", "yellow", and "red", respectively, see Simulation/Traffic Lights. Each character describes a link controlled by the traffic light. Only the state of the current program is saved (see also "Adding new Programs"). The attributes have the following meaning:

Optional Output#

If the attributes 'saveDetectors' or 'saveConditions' are set, additional attributes are written to the output. These attributes are only written for traffic lights controlled by detectors and for traffic lights with custom switching rules respectively.

TLS Switches#

Instantiating within the Simulation#

This output contains information about the green light phases of links (lane-to-lane connections). Each green light phase is describes by its begin, end and duration. An entry is written into the file as soon a green phase of a link ends. To enable writing tls switch information you have to add the following definition into one of your additional-files:

<timedEvent type="SaveTLSSwitchTimes" source="<TLS_ID>" dest="<OUTPUT_FILE>"/>

The attributes have herein the following meanings:

Generated Output#

The output looks like this:

<tlsSwitches>
   <tlsSwitch tls="<TLS_ID>" programID="<TLS_SUB_ID>" \
      fromLane="<LINKS_SOURCE_LANE>" toLane="<LINK_DESTINATION_LANE>" \
      begin="<BEGIN_OF_GREEN_PHASE>" end="<END_OF_GREEN_PHASE>" \
      duration="<DURATION_OF_GREEN_PHASE>"/>
   ... further switch points ...
</tlsSwitches>

Each entry is written into a single line. The values have the following meanings:

TLS Switch States#

Instantiating within the Simulation#

This output saves tls-states as the TLS States - output does but not every second but only at times the phases or the program (see also "Adding new Programs") change. The output is instantiated by adding the following definition into one of your additional-files:

<timedEvent type="SaveTLSSwitchStates" source="<TLS_ID>" dest="<OUTPUT_FILE>"/>

The attributes have herein the following meanings:

Generated Output#

The output looks like this:

<tlsStates>
   <tlsState time="<SIM_STEP>" id="<TLS_ID>" programID="<TLS_SUBID>" phase="<PHASE_INDEX>" state="<STATE>"/>
   ... further states ...
</tlsStates>

Each entry is written into a single line. The values have the same meaning as those in the SaveTLSStates-output.

TLS Programs#

Instantiating within the Simulation#

To enable writing tls state information you have to add the following definition into one of your additional-files:

<timedEvent type="SaveTLSProgram" source="<TLS_ID>" dest="<OUTPUT_FILE>"/>

The attributes have herein the following meanings:

Generated Output#

The output is a loadable tlLogic element that records the complete state sequence of a traffic light:

<tlsStates>
   <tlLogic id="<TLS_ID>" programID="<TLS_SUBID>" type="static/>
      <phase state="..." duration="..."
      ...
   </tlLogic>
</tlsStates>

A new phase is saved whenever the state changes. A new tlLogic is written whenever the programID changes.

Coupled Lane Area Detectors#

Instantiating within the Simulation#

It is possible to add E2-detectors which are coupled to a traffic light. Then, the tls is used to determine the intervals (aggregation) time instead of giving a fixed aggregation time. In this case, output will be generated every time the traffic light switches. To use this feature set attribute tl="<TL_ID>" to the desired traffic light id instead of attribute <period>:

<e2Detector id="<ID>" lane="<LANE_ID>" pos="<POSITION_ON_LANE>" length="<DETECTOR_LENGTH>" tl="<TL_ID>" file="<OUTPUT_FILE>" [timeThreshold="<FLOAT>"] [speedThreshold="<FLOAT>"] [jamThreshold="<FLOAT>"]/>

A further feature allows you to collect measures only for the time the light turns red for a certain link (connection between the incoming and the outgoing lane). This allows measuring the maximum jam length in front of a red traffic light for this link. To enable this, one has to add the name of the following lane: to="<LANE_ID>" to the list of attributes. The incoming lane is already given by the "lane"-attribute.