Use Cases
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 UCs 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):
An example of Use Case for the Road Intersection Safety (UC 1a) application is the following one,
related to Accidents at Intersections:
A crash happens at an intersection resulting in a dangerous situation;
the drivers approaching an intersection are warned about such event.
The purpose of this use case is to avoid critical situations resulting from an accident.
Intersections are probably the most complex part of road infrastructures and places where collisions
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 maneuver
Three UCs have been synthesized for the Lane Change Maneuver application:
- Lane change maneuver for trucks with blind spots
- Lane change maneuver for car/trucks
- Lane change maneuver for ramp in motorways
Example use case (for more information please click on the figure below):
As an example use case the one related to Lane Change Maneuver for Trucks with blind spots is presented (UC 2a).
This scenario aims to inform and/or warn truck driver (V1) about the presence of other vehicle (V2) around
him during maneuver, especially during lane change maneuver.
Even if specific rear mirror help driver to have a good vision around its vehicle, some blind spot already
exist in some situations. Due to the dimension of the truck, it is relevant in some situations to improve
the driver information about the presence of other vehicles around him. The relative speed information with
other vehicles can be taken into account to appreciate the safety of some maneuvers. Some lateral collision
or/and rear end collision can be avoided with other vehicles.
The purpose of this use case is to avoid accident due to blind spot with trucks during a lane change maneuver.
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Safe Overtaking application
Three Use Cases are proposed for this application:
- Safe overtaking in urban and semi urban roads with PTW (Powered Two Wheelers)
already in overtaking the Other Vehicle (OV)
- PTW overtaking OV while OV is turning left to park area
- PTW overtaking OV while OV is turning left to park area
Example use case (for more information please click on the figure below):
The one related to Safe Overtaking in urban and semi urban roads with PTW already in overtaking is presented (UC 3a):
Host vehicle (1) starts to overtake vehicle (3) while a Powered Two Wheelers (2) is already in overtaking
maneuver PTW (2) informs the host vehicle (1) about its maneuver.
This situation is critical for PTW users due to blinds spots and differential of speed between PTW and car that does
not allow the driver to be aware about the presence of motorcyclist. The purpose behind this use case is to avoid
collision between PTW and vehicles by giving a warning to the vehicle.
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Head on collision warning
Three UCs are 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 UC is related to a situation where host vehicle attempts an overtaking maneuver and is facing the risk
of a head on collision due to the approaching of a second vehicle from the opposite lane. The second UC is
describing the same situation, but the perspective (host vehicle) is the one of the vehicle which is driving
normally and it is facing the head on collision risk due to a hazardous overtaking attempt started by a second
vehicle. Third UC 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):
As an example use case the one related to Head on collision warning due to hazardous overtaking attempt by host vehicle
is presented. As in the pictogram below, host vehicle (1) attempts an overtaking maneuver to 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 maneuver, so as 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 an 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):
As an example use case the one related to Rear end collision due to the presence of a heavy vehicle climbing up through
a hairpin curve at a low speed is presented. A vehicle (2) is climbing up a sharp hairpin curve, while a heavy vehicle
(1), short ahead, is driving at a low speed due to the steep road.
The purpose behind this use case is to warn the driver of vehicle 1 (as shown in the figure) of a possible danger of
rare end collision, so as 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):
As an example use case, the one related to Speed limitation and safety distance and trucks driver recommendations is
presented: This scenario aims to provide to the vehicle driver (2) some recommendations in term of speed and safety
distance regarding the behaviour or status of the vehicle in front. Special focus can be done 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 recommendation to the driver regarding additional information coming
from other vehicles. The purpose behind this use case is to provide recommendations to the driver (2), taking into account
the status or the behaviour of the 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 UCs have been collected for the Frontal Collision Warning application:
- Frontal collision warning due to static obstacle in front
- Frontal collision warning due to 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):
As an example use case the one related to Frontal Collision Warning due to static obstacle in front is
presented. This scenario aims to inform and/or warn truck drivers about the presence of a static obstacle
in front.
Radar or Lidar sensor performances are limited (distance around 200 meters), and in some cases, the driver can not be
informed enough in advance about a risk in front. For instance, sensor performances can be limited if an accident
occurs after a curve or due to bad weather conditions. Better 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 static obstacle on the road in front. It can be for instance due to accident or a vehicle
breakdown, etc.
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Road condition status
Two UCs 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):
As an example use case the one related to Road condition status – V2I based is presented.
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 taking into
account 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 behind
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)
is collecting and analysing the information.
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Curve warning
One Use Case is proposed 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):
As an example use case the one related to Vulnerable road users crossing a road, based on on-board detection
system is presented. This scenario aims to inform/warn/recommend 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 to the bad visibility: hidden by a vehicle (V1 or V3)
or due to bad weather condition
Road with two lanes on 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 vulnerable road user can
be not detected by other vehicle drivers (V2) which are approaching. Several reasons for this:
- VRU are hidden by a vehicle (especially bus and trucks)
- There is bad visibility like sun reflection, bad weather, or during the night
The purpose of this use case is to avoid collision between vehicle and vulnerable road user,
for instance a pedestrian or a bicycle.
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