Term Definition
Apportionment A process whereby the elements of a system are sub-divided between the various items which comprise the system to provide individual targets (EN50126).
Assessment The undertaking of an investigation in order to arrive at a judgement, based on evidence, of the suitability of a product (EN50126)
Audit A systematic and independent examination to determine whether the procedures specific to the requirements of a product comply with the planned arrangements, are implemented effectively and are suitable to achieve the specified objectives (EN50126).
Comissioning A collective term for the activities undertaken to prepare a system or product prior to demonstrating that it meets its specified requirements (EN50126).
Common Cause Failure A failure which is the result of an event(s) which causes a coincidence of failure states of two or more components leading to a system failing to perform its required function (EN50126).
Compliance A demonstration that a characteristic or property of a product satisfies the stated requirements (EN50126).
Crossing Clearance Zone It is a zone defined in at-grade crossings, as the intersection between the ARTS lane and the crossing roads plus a buffer area that extends in the direction of the crossing road. If the crossing is protected with physical barriers, the buffer zone extends until these barriers. The main objective of the buffer zone is to prevent that an obstacle coming on the crossing road reaches the ARTS vehicle’s emergency volume while the vehicle is not at rest, either using on-board or infrastructure-based sensors. Figure 10 shows an example of the ARTS crossing clearance zone (a) and the buffer zone (b) in one of the ARTS integration scenarios.
Dependent Failure The failure of a set of events, the probability of which cannot be expressed as the simple product of the unconditional probabilities of the individual events (EN50126).
Distance to Stop Line Distance from the vehicle’s front to the next stop line in the vehicle’s planned path applying comfort deceleration and jerk values (based on ETSI TS 102 637-2).
Down Time The time interval during which a product is in a down state. (IEC 60050(191)).
Emergency Braking Distance The distance required by the ARTS vehicle to come to a complete stop at emergency deceleration, calculated along its planned path.
Emergency Deceleration Is the maximum deceleration that the ARTS vehicle can apply.
Emergency Zone Is a zone composed of a zone centred on the ARTS vehicle whose dimensions are the ARTS vehicle’s width and length + 0.5 m on each side and a zone surrounding the vehicle path of width the vehicle width + 0.5 [m] on each side or the lane width. Its length is the emergency braking distance, meaning that it depends on the current vehicle velocity. Any static obstacle detected in this zone must force the vehicle to stop at an emergency deceleration. The emergency zone is done through the use of on-board sensors and infrastructure sensors, if available.
Fail-Safe Designed to return to a safe condition in the event of a failure or malfunction.
Failure A failure is any fault in the system that prevents a vehicle from completing its planned journey or stops a vehicle in the station or depot movement areas.
Failure cause The circumstances during design, manufacture or use which have led to a failure. (IEC 60050(1 91)).
Failure mode The predicted or observed results of a failure cause on a stated item in relation to the operating conditions at the time of the failure (EN50126).
Failure rate The limit, if this exists, of the ratio of the conditional probability that the instant of time, T, of a failure of a product falls within a given time interval (t, t+Jt) and the length of this interval, It, when It tends towards zero, given that the item is in an up state at the start of the time interval (EN50126).
Fault mode One of the possible states of a faulty product for a given required function. (IEC 60050(191)).
Function Implementation of a set of rules to achieve a specified goal FCW
Hazard A physical situation with a potential for human injury (EN50126).
Hazard log The document in which all safety management activities, hazards identified, decisions made and solutions adopted are recorded or referenced. Also known as a “Safety Log”. (ENV 50129).
Infrastructure Support levels for Automated Drivring (ISAD) ISAD levels can be assigned to parts of the network in order to give automated vehicles and their operators guidance on the “readiness” of the road network for the coming highway automation era. Infrastructure support levels are meant to describe road or motorway sections rather than whole road networks. The following levels are being developed in INFRAMIX project:
Levels of Automation According to the SAE Definitions, this are the level of automation:
You can also check them in:
Mission An objective description of the fundamental task performed by a system (EN50126).
Mission Profile Outline of the expected range and variation in the mission with respect to parameters such as time, loading, speed, distance, stops, tunnels, etc., in the operational phases of the lifecycle (EN50126).
Obstacle Any object present in the environment and not belonging to the Frame, Scope or Regulation layers, which should be protected from harm (other road users, domestic animals and property) or capable of creating hazard to the ARTS and/or the ARTS’ end users.
Obstacle Detection Zone Is a zone that includes the safety zone plus a front zone with at least a half circle zone of radius the length the emergency braking distance. All the potential obstacles must be detected and tracked in the obstacle detection zone, in order to calculate a collision risk by regarding the ARTS vehicle planned path and the obstacle predicted trajectory. The collision risk must be assessed in order to adapt the velocity, warn pedestrians/bicyclists in a dangerous trajectory or make an emergency braking. The collision risk calculation shall take into account large objects in the environment, located near the ARTS lane, which can hide road users, which may become potential obstacles. The obstacle detection zone observation is done through the use of on-board sensors and infrastructure sensors, if available. In case of segregation, obstacle detection zone and safety zone are restricted to the segregation limits (continuous barriers and crossing barriers).
Operational Design Domain (ODD) According to the SAE Definition, ODD are Operating conditions under which a given driving automation systems or feature thereof is specifically designed to function, including, but not limited to, environmental, geographical, and time-of-day restrictions, and/or the requisite presence or absence of certain traffic or roadway characteristics.
Repair That part of a corrective maintenance in which manual actions are performed on a item. (IEC 60050(191))
Restoration That event when an item regains the ability to perform a required function after a fault. (IEC 60050(191)).
Risk The probable rate of occurrence of a hazard causing harm and the degree of severity of the harm (EN50126).
Risk Assessment The determination of the value of a risk related to a concrete situation of a hazard.
Safe State  Condition of an ARTS vehicle where it does not present an impending hazard.
Safety Freedom from unacceptable risk of harm (EN50126).
Safety Authority Often a national government body responsible for setting or agreeing the safety requirements for a ARTS and ensuring that the ARTS complies with the requirements (derived from EN50126).
Safety Case  The documented demonstration that the product complies with the specified safety requirements (EN50126).
Safety Integrity The likelihood of a system satisfactorily performing the required safety functions under all the stated conditions within a stated penod of time (EN50126).
Safety Zone Is a zone that has the same shape as the emergency zone but is larger and longer at front. Its width is the lane width. Its length is the emergency braking distance + a buffer distance of 5 [m]. The presence of any obstacle in this zone must force the vehicle to decelerate to prevent that an obstacle reaches the emergency zone while the vehicle is not at rest. The safety zone is done through the use of on-board sensors and infrastructure sensors, if available. In case of segregation, obstacle detection zone and safety zone are restricted to the segregation limits (continuous barriers and crossing barriers).
Scenario A use case in a specific situation. car following with speed above 70 km/h sunny day FCW on
Situation One specific level or a combination of more specific levels of situational variables. rain, dark, one passenger in vehicle, motorway, … (either each for itself, or the combination)
Station Clearance Zone It is a zone defined by the length of the edge of the station adjacent to the ARTS lane and a width such that it guarantees that there are no hazards for the end-users during the ARTS vehicle docking and undocking manoeuvres or in case an ARTS vehicle passes the station. Its objective is to replace the safety role of the station doors in ARTS stations not equipped with doors. The station clearance zone is part of the emergency zone.
System A combination of hardware and software enabling one or more functions Headway sensor + controller + HMI + data logger application software running on a system implementing one or more functions
Systematic Failures Failures due to errors in any safety lifecycle activity, within any phase, which cause it to fail under some particular combination of inputs or under some particular environmental condition (EN50126).
Test Scenario Test setup in which scenarios are triggered in order to collect data specific to this scenario event something that happens in a specific period of time which is individuated combining (preprocessed) measures according to predefined rules. crash, near-crash, overtaking manoeuvre, strong deceleration
Tolerable Risk  The maximum level of risk of a product that is acceptable to the Authority. The Authority is responsible for agreeing the risk acceptance criteria and the risk acceptance levels with the Safety Regulatory Authority (SRA).
Usually, it is the SRA or the RA by agreement with the SRA that defines risk acceptance levels. Risk acceptance levels currently depend on the prevailing national legislation or national/other regulations. In many countries risk acceptance levels have not yet been established and are still in progress and/or under consideration.
Use Case A specific event in which a system is expected to behave according to a specified function car following
Validation Confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use have been fulfilled (EN50126).
Verification Confirmation by examination and provision of objective evidence that the specified requirements have been fulfilled (EN50126).

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