Introduction#

Since version 1.9.1 SUMO supports simulation of Green Light Optimal Speed Advisory (GLOSA) via the glosa device. This allows vehicles to avoid stops at traffic lights when the phase is about to change.

Note

While the glosa capabilities are under development, their status can be checked via Issue #7721.

Equipping vehicles#

To attach a glosa device to a vehicle, the standard device-equipment procedures can be applied using <device name>=glosa.

For instance, a single vehicle can be equipped with glosa as in the following minimal example

    <vehicle id="v0" route="route0" depart="0">
        <param key="has.glosa.device" value="true"/>
    </vehicle>

GLOSA functions#

Slowing Down#

When a vehicle is approaching a red light the time until reaching the stop line is compared with the time until the signal (for the intended movement) changes to green. If the vehicle would reach the stop line before the switch, a slow-down maneuver may be undertaken (speedFactor is changed to a lower value).

If the speed can be reduced within reasonable bounds (glosa.min-speed), the speed is reduced to the maximum possible value so that the vehicle reaches the stop line at the time of the phase change. Speed adaptation follows a trapezoid:

Decelerate/Accelerate to the calculated speed value
Maintain the calculated speed value
Accelerate back to the desired maximum speed before crossing the junction

Speeding up#

When a vehicle is approaching a green light and the time until reaching the stop line is higher than the remaining green phase duration, a speed-up maneuver may be undertaken.

If driving with a higher speedFactor (configured with glosa.max-speedfactor) allows to reach the stop line within the remaining green time, the speedFactor is set to a higher value.

The speedFactor is changed back to the default after passing the traffic light.

Queue length calculation (since v1.22)#

By default, a vehicle with a glosa device approaches the stop line with the highest possible velocity and ignores vehicles, that are already queuing at the traffic light.

To estimate the queue length of waiting vehicles, a traffic light can be equipped with sensors. This information is sent to other vehicles, which then adapt their arrival time. The behavior can be simulated by setting param device.glosa.use-queue to true.

    <vehicle id="v0" route="route0" depart="0">
        <param key="has.glosa.device" value="true"/>
        <param key="has.glosa.use-queue" value="true"/>
    </vehicle>

The traffic light also needs to be equipped with detectors, e.g. by setting the tls to delay_based. The maximal detection length can be changed via detectorRange.

    <tlLogic id="C" type="delay_based" programID="0">
        <param key="detectorRange" value="100" />
    </tlLogic>

Note

Although the traffic light may be of type delay_based, it can still run a static program.

Traffic lights#

All traffic lights types supply time-to-switch information via the duration attribute of their phases. Since v1.22, the glosa device not only calculates the time to the next phase switch, but rather retrieves the phase when the vehicle arrives at the intersection (may be multiple phase switches ahead).

Caution

This may cause invalid maneuvers with traffic-actuated traffic lights that may vary their phase duration.

The communication range may be customized by setting param "device.glosa.range" on the tlLogic. This may also be used to disable glosa functions for specific intersections. To update the parameter for a program that is embedded in the .net.xml file the following element can be loaded via --additional-files:

    <tlLogic id="C" programID="0">
        <param key="device.glosa.range" value="60"/>
    </tlLogic>

Parameters#

The following parameters affect the operation of the glosa device.

device.glosa.range: (maximum range from stop line at which glosa functions become active (default 100). If the current traffic light also sets this parameter, the minimum value of the device and tls parameter is used.
device.glosa.min-speed: minimum speed for slow-down maneuver (default 5m/s)
device.glosa.max-speedfactor: maximum speedFactor for trying to reach a green light (default 1.1) Setting a value of 1 will ensure perfect compliance with the speed limit but may still cause slow drivers to speed up.
device.glosa.add-switchtime (v1.21): A vehicle with GLOSA tries to reach the intersection with maximal speed just before the light signal turns green. This results in late braking maneuvers. By adding a time offset to the phase change, the vehicle arrives X s later (default 0 s).
device.glosa.override-safety (v1.21): Default behavior is that a vehicle with glosa receives a speed advice and the driver tries to match this speed. When approaching a red light, the driver would start to decelerate, despite a higher speed advice. That's because we can't be sure, if the traffic light will really switch By setting this boolean parameter to true, the vehicle will ignore the current traffic light phase and strictly follow the speed advice (default false). This would somewhat be possible with automated vehicles and guaranteed phase durations.
device.glosa.ignore-cfmodel (v1.21): Default behavior is that a vehicle with glosa receives a speed advice and this advice changes the speedFactor. Therefore, the speed of the vehicle in the next time step is dependent on the car-following model. By setting this boolean parameter to true, the device calculates a specific speed time line (default false). This is explicitly followed by the vehicle. This would somewhat mimic the behavior of an automated vehicle.
has.glosa.use-queue (v1.22): By setting this boolean parameter to true, the vehicle takes the queue length in front of the traffic light into account (default false).
jmDriveAfterYellowTime: This junction model parameter encodes willingness to continue driving at yellow depending on running duration of the yellow phase (default 0). The value will be taken into account when checking the feasibility of a speed-up maneuver

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