Use Cases
A user centred design approach was followed for the formulation of the SAFESPOT Use Cases. In order to
collect a proper set of User Needs and Requirements - and also as a general foundation for the overall
analysis a Structured Analysis tool was used to describe the SAFESPOT system by means of the adoption
of Use Cases.
For detailed information on the SAFESPOT applications and use cases please refer to the
SAFESPOT Deliverable 8.4.4
"Use cases, functional specifications and safety margin applications for the SAFESPOT Project"
Intersection Safety application
Six Use Cases have been collected regarding the Intersection Safety application:
- Accident at intersections
- Obstructed view at intersection
- Permission denial to go-ahead
- Defect traffic signs
- Other vehicle brakes hard due to red light
- Approaching emergency vehicle warning
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Intersection Safety application (UC 1a):
A crash happens at an intersection creating a dangerous situation. Now, drivers approaching this intersection will be warned about the crash.
The purpose of this use case is to avoid critical situations resulting from an accident beforehand. Intersections are probably the most complex part of road infrastructures and places where collisions can result in serious injury or death. An accident at an intersection can result in other accidents as an unforeseen situation would exist. On intersections traffic-flow is very complex, so the driving behaviour of other drivers could change immediately, due to such unforeseen situations.
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Lane Change Manoeuvre
Three Use Cases have been synthesized for the Lane Change Manoeuvre application:
- Lane Change Manoeuvre for trucks with blind spots
- Lane Change Manoeuvre for car/trucks
- Lane Change Manoeuvre for ramp in motorways
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Lane Change Manoeuvre application (UC 2a). This scenario aims to inform and/or warn the truck driver (V1) about the presence of other vehicles (V2) around him during manoeuvring, especially during lane change manoeuvres.
Even if special side mirrors help the driver to have a good vision around his vehicle, some blind spots already exist in some situations. Due to the dimension of the truck, in some situations it is relevant inform the driver about the presence of other vehicles around him. The relative speed information of other vehicles can be taken into account to appreciate the safety of some manoeuvres. Some lateral collisions or/and rear end collisions with other vehicles can be avoided.
The purpose of this Use Case is to avoid accidents due to blind spots on trucks during a Lane Change Manoeuvre.
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Safe Overtaking application
Three Use Cases have been realized for this application:
- Safe overtaking in urban and semi urban roads with PTWs (Powered Two Wheelers) -already while overtaking the Other Vehicle (OV)
- PTW overtaking OV while OV is turning left to park area
- PTW overtaking OV while a different OV is turning left to park area
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Safe Overtaking application (UC 3a):
Host vehicle (1) starts to overtake vehicle (3) while a Powered Two Wheeler (2) is already starting a
overtaking manoeuvre. PTW (2) will now inform the host vehicle (1) about its manoeuvre.
This situation is critical for PTW users due to blinds spots and differential of speed between the PTW and the car. The purpose of this use case is to avoid collisions between PTWs and vehicles by sending out a warning to the vehicle.
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Head On Collision Warning
Three Use Cases have been collected for the Head On Collision Warning function:
- Head On Collision Warning due to hazardous overtaking attempt by host vehicle
- Head On Collision Warning due to hazardous overtaking attempt by a second vehicle
- Head On Collision Warning due to the presence of a coach vehicle climbing down through a hairpin curve
The first Use Case is related to a situation where the host vehicle attempts an overtaking manoeuvre and is facing the risk of a head on collision due to the approaching of a second vehicle from the opposite lane. The second Use Case describes the same situation, but the perspective (host vehicle) is the one of the vehicle which is driving normally and is facing the head on collision risk due to a hazardous overtaking attempt started by a second vehicle. The third Use Case is referring to a completely different situation, where the risk of a head on collision is due to the presence of a coach climbing down through a hairpin curve.
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Head On Collision Warning function: As in the pictogram below, host vehicle (1) attempts to overtake vehicle (3) which obstructs the driver's (1) field of view, while vehicle (2) is approaching from the opposite lane.
The purpose behind this use case is to warn the driver of vehicle (1), that an oncoming vehicle is in the adjacent lane and thus it is needed to delay or abort the overtaking manoeuvre; as well to avoid or reduce the accidents linked to head on collision situations.
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Rear End Collision
Two Use Cases have been identified for the Rear End Collision application:
- Rear End Collision due to the presence of a heavy vehicle climbing up through an hairpin curve at a low speed
- Rear End Collision due to the presence of a slower vehicle at the end of a hilly road segment
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Rear End Collision Warning function: A vehicle (2) is climbing up a sharp hairpin curve, while a heavy vehicle (1) shortly ahead is driving at a low speed due to the steep road.
The purpose of this use case is to warn the driver of vehicle (1) of a possible danger of rear end collision; as well to inform the host vehicle in a situation where the direct sensing capabilities of the involved vehicles cannot detect the potential risk.
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Speed Limitation and Safety Distance
Three Use Cases have been identified for the Speed Limitation and Safety Distance application:
- Speed Limitation and Safety Distance and trucks driver recommendations
- Safety Margin Assistant on black spots – tunnels
- Safety Margin Assistant on black spots – reduction of lanes
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Speed Limitation and Safety Distance application: This scenario aims to provide recommendations in term of speed and safety distance to the vehicle driver (2) regarding the behaviour or status of the vehicle in front. Special focus can be applied on trucks carrying dangerous goods.
Some existing recommendations on Speed Limitation and Safety Distance have been considered in some previous projects. Some new considerations can be added to improve the recommendations sent to the driver regarding additional information coming from other vehicles. The purpose of this use case is to provide recommendations to the driver (2), considering the status or behaviour of vehicle (1). For instance, if the vehicle (1) is carrying dangerous goods, the recommendation to the driver could be to increase the safety distance.
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Frontal Collision Warning
Three Use Cases have been collected for the Frontal Collision Warning application:
- Frontal collision warning due to a static obstacle in front
- Frontal collision warning due to a static obstacle in a tunnel
- Frontal collision warning due to abnormal vehicle behaviour in front
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Frontal Collision Warning application: This scenario aims to inform and/or warn truck drivers about the presence of a static obstacle in front of them.
Radar or Lidar sensor performances are limited (distance around 200 meters), and in some cases, the driver can not be informed early enough about a risk in front of him. For instance, sensor performances can be limited by bad weather conditions or by an accident appearing after a curve. Improved anticipation for trucks is important to safely stop the vehicle. The purpose of this use case is to inform or/and warn the driver in order to anticipate the vehicle deceleration caused by a static obstacle on the road in front. The static obstacle can be for instance due to an accident or a vehicle breakdown etc.
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Road Condition Status
Two Use Cases have been collected regarding the Road Condition Status – Slippery Road application:
- Road Condition Status – V2I Based
- Road Condition Status - V2V Based
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Road Condition Status: This scenario aims to inform and/or the driver in V2 about the road condition status detected by V1. The data is transferred via a road control centre.
The infrastructure (road monitoring centre) can enhance the information on the road condition by collecting information from several vehicles as well as incorporating other data such as weather data. The infrastructure is also monitoring the road condition by listening to the V2V communication between the vehicles. The purpose of this use case is to inform the driver in vehicle (2) about the road condition status measured by vehicle (1) so that the driver of vehicle (2) can be informed about the current road condition. The infrastructure (road monitoring centre) collects and analyses the information.
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Curve Warning
One Use Case has been realized for the Curve Warning application:
- UC9a - Curve Warning in rural black spots, based on a transponder in the infrastructure keeping
memory of the speeds adopted by passing vehicles.
For more information on this use case please click on the figure below.
Host vehicle (1) transmits to an infrastructure transponder (3) its speed and (possibly) other vehicle dynamics
information. Later, a vehicle approaching to the rural black spot (2) receives this information, adapting its
speed depending on multiple parameters, including map and navigational information, if available, and the
behaviour of other vehicles.
By broadcasting information from the host-vehicle, also a vehicle approaching a sharp curve without any
digital maps or other navigation systems installed on-board, can travel inside the curve safely (with the
suggestion of reference speed to keep). On the other hand, if the vehicle is already equipped with digital
maps, the information of how other vehicle behold in the same situations can help to reduce the number of
false and missing alarms. The purpose of this use case is to avoid or reduce the accidents due to approaching
a sharp curve with high speed.
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Vulnerable Road User Detection and Accident Avoidance
The Vulnerable Road User Detection and Accident Avoidance function is the single function
belonging to the VURU cluster of applications. For this application three Use Cases have been
collected (first two belonging to the same situation related to the VRU crossing a road):
- Vulnerable Road Users crossing a road, based on on-board detection system
- Vulnerable Road Users crossing a road, based on environment analyses
- Vulnerable Road Users in blind spots of a truck
Example use case (for more information please click on the figure below):
Here is an example of the first Use Case for the Vulnerable Road User Detection and Accident Avoidance function:
This scenario aims to inform/warn/recommend the vehicle driver about the presence of a Vulnerable Road User who is crossing a road. The vehicle V1 is equipped with an on-board VRU detection system.
A VRU is not detected by the driver V2 due the truck V2 blocking his sight or due to bad weather conditions.
Road with two lanes in the same direction
Road with one lane in each direction
Especially in urban and extra-urban roads with two or more lanes, the presence of VRUs can not be detected by other approaching vehicle drivers (V2). There are several reasons for this:
- VRUs are hidden by a vehicle (especially buses and trucks)
- There is bad visibility like sun reflection, bad weather, or darkness at night time
The purpose of this use case is to avoid a collision between vehicles and Vulnerable Road Users, for instance pedestrians or cyclists.
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