ISO 23376:2021

Intelligent transport systems - Vehicle-to-vehicle intersection collision warning systems (VVICW) - Performance requirements and test procedures

This document specifies performance requirements and test procedures for systems capable of warning the subject vehicle driver of a potential crossing-path collision with other vehicles at intersecting road segments. Vehicle-to-vehicle intersection collision warning systems (VVICW) rely on vehicle-to-vehicle (V2V) communications and relative positioning between the subject vehicle and crossing-path vehicles (remote vehicles). V2V data, such as position, speed and heading are used to evaluate if an intersection collision is imminent between the subject and remote vehicles. The performance requirements laid out in this document specify the warning criteria for these systems. In addition, VVICW operate in specified subject and remote vehicle speed ranges, road intersection geometries and target vehicle types. Moreover, the requirements for the V2V data will be specified. The scope of this document includes operations on intersecting road segments (physically intersecting roads), and motor vehicles including cars, trucks, buses and motorcycles. Responsibility for the safe operation of the vehicle remains with the driver.

Systèmes de transport intelligents — Systèmes d'alerte de collision aux intersections de véhicule-à-véhicule (VVICW) — Exigences de performance et procédures d'essai

General Information

• Status: Published
• Publication Date: 06-Dec-2021
• ICS: 35.240.60 - IT applications in transport
• ICS: 43.040.80 - Crash protection and restraint systems
• Technical Committee: ISO/TC 204 - Intelligent transport systems
• Drafting Committee: ISO/TC 204/WG 14 - Vehicle/roadway warning and control systems
• Current Stage: 6060 - International Standard published
• Start Date: 07-Dec-2021
• Due Date: 04-Apr-2022
• Completion Date: 07-Dec-2021

Overview

ISO 23376:2021 - Intelligent transport systems - Vehicle-to-vehicle intersection collision warning systems (VVICW) - specifies performance requirements and test procedures for systems that warn drivers of potential crossing‑path collisions at road intersections. The standard focuses on VVICW that use vehicle‑to‑vehicle (V2V) communications and relative positioning (GNSS, DSRC and similar V2V data) - exchanging position, speed and heading - to assess collision threat and issue driver alerts. The scope covers operations on physically intersecting road segments and motor vehicles including cars, trucks, buses and motorcycles. Responsibility for safe vehicle operation remains with the driver.

Key Topics

• Minimum enable conditions
  • Detect availability of V2V communications at junctions
  • Receive valid V2V messages with GNSS position, speed and heading
  • Determine subject vehicle (SV) GNSS position and dynamics
• Scenario coverage
  • Crossing scenarios (vehicles crossing laterally through intersections)
  • Oncoming scenarios (turning across paths of opposite‑direction traffic)
  • Both moving and initially‑stopped SV cases
• Necessary system functions
  • V2V message reception and localization
  • Monitoring of SV and remote vehicle (RV) dynamics (heading, speed, acceleration)
  • Threat evaluation using metrics such as time to collision (TTC), enhanced TTC (ETTC) and required deceleration
  • Driver alerting when warning criteria are met
• Warning provisions
  • Defined output modalities and timing criteria (when to warn, when not to warn)
  • Operating speed ranges, intersection geometries and target vehicle types
• Test procedures
  • Defined warning and no‑warning test cases for crossing and oncoming scenarios
  • Requirements to validate system performance against the standard

Applications

ISO 23376:2021 is intended for organizations designing, validating and deploying intersection collision warning systems:

• Vehicle OEMs integrating VVICW as part of advanced driver assistance systems (ADAS)
• V2V hardware/software suppliers implementing V2V messaging, localization and threat assessment
• Test laboratories and certification bodies performing performance validation and compliance testing
• Traffic safety researchers and road authorities evaluating ITS strategies to reduce intersection collisions

Practical benefits include improved driver awareness at intersections where line‑of‑sight sensors are limited, standardized test methods for consistent performance evaluation, and clearer integration requirements for V2V data.

Related standards

ISO 23376:2021 complements other intelligent transport systems and V2V communication and localization frameworks (e.g., DSRC and GNSS‑based positioning standards) and aligns with ISO/TC 204 work on ITS.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23376
First edition
2021-12
Intelligent transport systems —
Vehicle-to-vehicle intersection
collision warning systems (VVICW) —
Performance requirements and test
procedures
Systèmes de transport intelligents — Systèmes d'alerte de collision
aux intersections de véhicule-à-véhicule (VVICW) — Exigences de
performance et procédures d'essai
Reference number
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.3
5 Requirements . 4
5.1 Minimum enable conditions . 4
5.2 Minimum required VVICW scenarios . 4
5.3 Necessary functions . 5
5.4 State transition diagram . . 6
5.4.1 General . 6
5.4.2 State functional description . 6
6 Warning provisions . 7
6.1 VVICW output . 7
6.2 Warning modality . 7
6.3 Warning criteria for crossing scenarios . 8
6.3.1 Warning requirements . 8
6.3.2 No warning provisions. 10
6.4 Warning criteria for oncoming scenarios . 11
6.4.1 Warning requirements . 11
6.4.2 No warning requirements . 11
7 V2V data provisions: permissions.12
8 Testing procedures .12
8.1 General .12
8.2 Crossing scenarios . . .12
8.2.1 Warning tests . 12
8.2.2 No warning tests . 14
8.3 Oncoming scenarios .15
8.3.1 Warning tests . 15
8.3.2 No warning tests . 16
Bibliography .18
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
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This document was prepared by Technical Committee ISO/TC 204, Intelligent transport systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Vehicle-to-vehicle intersection collision warning systems (VVICW) warn the driver to avoid potential
collisions at intersections. The VVICW warns the driver of imminent crashes with other vehicles
crossing at a road junction. The system relies on relative positioning, speed and heading between
vehicles determined using vehicle-to-vehicle (V2V) communication, such as dedicated short-range
communication (DSRC). It is intended to be used to avoid intersection crossing crashes, the most severe
crashes based on fatality counts. Due to limited field of view sensing, on-board sensor systems such as
camera, lidar and radar systems cannot be used efficiently for such systems. Figure 1 illustrates the
functional elements of VVICW.
The VVICW is a road level system that deals with conflict scenarios between vehicles driving on two
connected road segments sharing a common intersection. VVICW positioning requirements are not
demanding compared to those of red light violation warning systems, for example. A comprehensive set
of intersection collision scenarios can be found in Reference [1].
Figure 1 — Vehicle-to-vehicle intersection collision warning systems functional elements
v
INTERNATIONAL STANDARD ISO 23376:2021(E)
Intelligent transport systems — Vehicle-to-vehicle
intersection collision warning systems (VVICW) —
Performance requirements and test procedures
1 Scope
This document specifies performance requirements and test procedures for systems capable of warning
the subject vehicle driver of a potential crossing-path collision with other vehicles at intersecting road
segments.
Vehicle-to-vehicle intersection collision warning systems (VVICW) rely on vehicle-to-vehicle (V2V)
communications and relative positioning between the subject vehicle and crossing-path vehicles
(remote vehicles). V2V data, such as position, speed and heading are used to evaluate if an intersection
collision is imminent between the subject and remote vehicles. The performance requirements laid out
in this document specify the warning criteria for these systems.
In addition, VVICW operate in specified subject and remote vehicle speed ranges, road intersection
geometries and target vehicle types. Moreover, the requirements for the V2V data will be specified.
The scope of this document includes operations on intersecting road segments (physically intersecting
roads), and motor vehicles including cars, trucks, buses and motorcycles. Responsibility for the safe
operation of the vehicle remains with the driver.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
subject vehicle
SV
motor vehicle equipped with a VVICW
Note 1 to entry: A subject vehicle can be also a remote vehicle for another subject vehicle.
3.2
subject vehicle speed
subject vehicle velocity in the heading direction
3.3
remote vehicle
RV
motor vehicle equipped at minimum with a V2V transmission device and localization system and that
has the ability to possibly intersect the path of the subject vehicle
3.4
remote vehicle speed
longitudinal component of the remote vehicle velocity in the heading direction
3.5
intersecting road segment
physically intersecting roads that are described based on the number of road segments
Note 1 to entry: A road junction is where two or more road segments intersect.
Note 2 to entry: Roundabout, ramp/highway, street 4-way intersection and street 3-way intersection are
examples of intersection road geometry.
EXAMPLE 1 A four-way intersection, or crossroads, usually involves a crossing of two streets or roads. In
areas where there are rectilinear blocks and in some other cases, the crossing streets or roads are perpendicular
to each other. However, two roads may cross at a different angle. In a few cases, the junction of two road segments
can be offset from each other when reaching an intersection, even though both ends may be considered the same
street.
EXAMPLE 2 A three-way intersection is a junction between three road segments, a T junction where two arms
form one road, or a Y junction. The latter also known as a fork if approached from the stem of the Y.
3.6
time to collision
TTC
time that it takes a subject vehicle to collide with a remote vehicle assuming the relative velocity
remains constant
Note 1 to entry: For the VVICW, TTC is the time needed for the subject vehicle to reach the collision point. TTC is
therefore calculated using Formula (1):
d
c
t =− (1)
c
v
SV
where
t is the time to collision;
c
d is the distance of the subject vehicle from the collision point;
c
v is the speed of the subject vehicle.
SV
3.7
enhanced time to collision
ETTC
time that it takes a subject vehicle to collide with a remote vehicle assuming the relative acceleration
between the subject vehicle and the remote vehicle remains constant
Note 1 to entry: For the VVICW, ETTC is the time needed for the subject vehicle to reach the collision point and
not a remote vehicle. An enhanced arrival time therefore takes into consideration the acceleration of the subject
vehicle. Since the collision point is fixed at any point in time, the value of zero is substituted for v and a . ETTC
RV RV
is calculated using Formula (2):

 
−−()νν −−()νν −∗2 ()aa− ∗d
RV SV RV SV RV SV c
 
 
t = (2)
c,e
aa−
()
RV SV
where
t is the enhanced time to collision;
c,e
v is the speed of the remote vehicle;
RV
v is the speed of the subject vehicle;
SV
d is the distance of the subject vehicle from the collision point;
c
a is the acceleration of the remote vehicle;
RV
a is the acceleration of the subject vehicle.
SV
3.8
required deceleration
A
req
minimum deceleration that, if constant, enables the subject vehicle to stop at a defined calculated
distance from the current subject vehicle position
Note 1 to entry: A is calculated using Formula (3):
req
v
SV
A = (3)
req
2 dd−
()
sp r
where
A is the required deceleration;
req
v is the speed of the subject vehicle;
SV
d is the current distance from stopping point;
sp
d is the reaction travel distance.
r
4 Symbols and abbreviated terms
A required deceleration
req
a acceleration of the remote vehicle
RV
a acceleration of the subject vehicle
SV
d distance of the subject vehicle from the collision point
c
d reaction travel distance
r
d minimum required distance measured from the stop line
sl,min
d current distance from stopping point
sp
DSRC dedicated short-range communication
GNSS global navigation satellite system
l length of the remote vehicle
RV
l length of the subject vehicle
SV
T tolerance
(1,2, etc.)
t braking system response time
b
t time to collision
c
t enhanced time to collision
c,e
t driver brake reaction time
resp
v speed of the subject vehicle
SV
v speed of the remote vehicle
RV
v projected speed of the remote vehicle at the arrival time
RV,p
v maximum subject vehicle speed for VVICW operation
SVmax
v minimum subject vehicle speed for VVICW operation
SVmin
v projected speed of the subject vehicle at the arrival time
SV,p
V2V vehicle-to-vehicle
VVICW vehicle-to-vehicle intersection collision warning system
5 Requirements
5.1 Minimum enable conditions
Vehicles equipped with VVICW shall be capable of the following:
— determining if the V2V communication between the SV and RVs is available at the road junction;
— receiving valid V2V communication that provides the GNSS position, speed and heading of RVs
approaching the road junction;
— determining GNSS position, speed and heading of the SV approaching the road junction.
5.2 Minimum required VVICW scenarios
The purpose of the VVICW is to provide the drivers of the SVs with alerts that assist them in avoiding or
reducing the severity of impending collisions associated with the following scenarios:
a) Crossing scenarios (illustrated in Figure 2):
1) cross straight through an intersection, across the path of a vehicle approaching from a lateral
direction;
2) cross straight through an intersection, after initially being stopped, across the path of a vehicle
approaching from a lateral direction.
b) Oncoming scenarios (illustrated in Figure 3):
1) turn left or right (depends on left or right driving rule) across the path of an oncoming vehicle
approaching from the opposite direction;
2) turn left or right (depends on left or right driving rule), after initially being stopped, across the
path of an oncoming vehicle approaching from the opposite direction.
Key
1 RV moving 3 RV moving
2 SV initially stopped, then accelerating 4 SV moving
Figure 2 — Crossing scenarios
Key
1 RV moving 3 RV moving
2 SV initially stopped, then turning left 4 SV moving
Figure 3 — Oncoming scenarios
5.3 Necessary functions
Vehicles equipped with VVICW shall be equipped to fulfil the following functions:
— receive V2V messages from RVs that provide data representing the position, speed and heading of
the RV;
— monitor SV and RV dynamics, including heading, heading change, speed and acceleration;
— determine the threat potential of collision with approaching RVs and evaluate the warning criteria;
— if needed, provide alerts to the driver of an impending collision with an RV in the intersection.
5.4 State transition diagram
5.4.1 General
The VVICW shall function according to the state transition diagram in Figure 4. Specific implementation
of the state transitions beyond that which is illustrated in Figure 4 is left to the manufacturer.
Figure 4 — VVICW state transition diagram
5.4.2 State functional description
5.4.2.1 Introduction
The VVICW state descriptions address the transition requirements of VVICW and identify which
functions shall be performed in each state.
5.4.2.2 VVICW Off
VVICW do not perform VVICW functionality in the Off state.
The conditions under which VVICW transiti
...