Vehicle Signalling

# Signaling

A vehicle's signals are encoded in an integer, each by one bit, encoding whether the according signal/... is on or off. Most signals are rather meant to be used by an external application. However, a few signals are computed in each step.

# Computed Signals

The following signals are computed in each time step. The value set via TraCI is only retained for the current time step.

- VEH_SIGNAL_BRAKELIGHT: The brake light is set whenever the vehicle is standing (not stopped) or when the vehicle decelerates beyond a threshold value. The signal value is used by the vehicles when trying to avoid jamming on an intersection.
- VEH_SIGNAL_BLINKER_RIGHT and VEH_SIGNAL_BLINKER_LEFT: The blinker is activated in either of the following conditions
  - The vehicle is about to take a turn at an intersection (activated 7 seconds before reaching the intersection)
  - Either of the continuous lane-change models is active
  - A desired lane change cannot be executed due to neighboring vehicles.
  - a vehicle is about to stop for parking
  - the vehicle is stopped on a lane that is not the rightmost usable lane (emergency blinkers on both sides are active)
- VEH_SIGNAL_EMERGENCY_BLUE: when switched on, a blinking blue light is shown in the GUI for vehicles with vClass="emergency" and shapeClass="emergency"

# Defined Signals

The following table shows the defined signals.

Name | Bit
--- | ---
VEH_SIGNAL_BLINKER_RIGHT | 0
VEH_SIGNAL_BLINKER_LEFT | 1
VEH_SIGNAL_BLINKER_EMERGENCY | 2
VEH_SIGNAL_BRAKELIGHT | 3
VEH_SIGNAL_FRONTLIGHT | 4
VEH_SIGNAL_FOGLIGHT | 5
VEH_SIGNAL_HIGHBEAM | 6
VEH_SIGNAL_BACKDRIVE | 7
VEH_SIGNAL_WIPER | 8
VEH_SIGNAL_DOOR_OPEN_LEFT | 9
VEH_SIGNAL_DOOR_OPEN_RIGHT | 10
VEH_SIGNAL_EMERGENCY_BLUE | 11
VEH_SIGNAL_EMERGENCY_RED | 12
VEH_SIGNAL_EMERGENCY_YELLOW | 13

Note

Sending a negative signal value immediately resets all signals to their computed values.

# See Also

- Vehicle Value Retrieval
- Change Vehicle State
- Accessing signal state without TraCI using --fcd-output

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