This standard specifies the technical requirements, test methods and inspection rules for rear marking plates used to improve the visibility of heavy and long vehicles as well as slow-moving vehicles (SMV) and their trailers from behind.
This standard is applicable to:
a) Heavy and long vehicles, including:
1) Articulated Grade II and III M vehicles;
2) N3 vehicles excluding semi-trailer tractors;
3) O1, O2 and O3 vehicles longer than 8.0m;
4) O4 vehicles;
5) Special operation vehicle refitted from truck chassis.
b) SMV: M, N and O vehicles with maximum design speed not greater than 40 km/h due to construction.
2 Normative References
The following normative documents contain provisions which, through reference in this standard, constitute provisions of this standard. For dated reference, subsequent amendments (excluding amending errors) to, or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest editions of these documents are applicable. For undated references, the latest edition of the normative document referred to applies.
GB/T 3978 Standard Illuminants and Geometric Conditions
GB 4785 Prescription for Installation of the External Lighting and Light-signaling Devices for Motor Vehicles and Their Trailers
GB/T 8427-1998 Textiles C Tests for Color Fastness C Color Fastness to Artificial Light: Xenon Arc Fading Lamp Test (eqv ISO 105-B02: 1994)
GB/T 10485-2007 Road Vehicles C Lighting and Light-signaling Devices C Environmental Endurance
GB 11564 Retroreflector Device for Motor Vehicles
3 Terms and Definitions
For the purpose of this standard, the following terms and definitions as well as those specified in GB 4785 and GB 11564 apply.
3.1 General terms
3.1.1
Sample unit
A complete, finished rear marking plate ready to be mounted on a vehicle and representative of current production.
3.1.2
Rear-marking plate
A readily identifiable plate with a specific shape and pattern faced with retroreflective and/or fluorescent material or devices to increase the visibility of corresponding vehicles.
3.1.3
Retroreflective material
A surface or device from which, where directionally irradiated, a relatively large portion of the incident light is retroreflected.
3.1.4
Retroreflecting device
An assembly ready for use and comprising one or more retroreflective optical units.
3.1.5
Fluorescence
Where certain substances are brought near to a source of ultraviolet or blue radiations, they often emit light with wavelength longer than exciting light. This phenomenon is called fluorescence. By day and under low light, fluorescent colors are brighter than normal colors because they reflect part of the incident light and in addition they emit fluorescence. However, at night, they are not brighter than normal colors.
3.2 Type of rear marking plate
3.2.1
SMV rear marking plate (class 1)
A triangular marking plate, without the top angle and with retroreflective and fluorescent material or device, for SMV.
3.2.2
SMV rear marking plate (class 2)
A triangular marking plate, without the top angle and with retroreflective material or device only, for SMV.
3.2.3
Rear marking plate for heavy vehicles (class 1)
A rectangular marking plate comprising red fluorescent material and yellow retroreflective material alternatively, for cargo truck and tractor.
3.2.4
Rear marking plate for long vehicles (class 2)
A rectangular marking plate comprising red fluorescent material for frame and yellow retroreflective material for center, for trailer and semitrailer.
3.2.5
Rear marking plate for heavy vehicles (class 3)
A rectangular marking plate comprising red and yellow retroreflective material alternatively, for cargo truck and tractor.
3.2.6
Rear marking plate for long vehicles (class 4)
A rectangular marking plate comprising red retroreflective material for frame and yellow retroreflective material for center, for trailer and semitrailer.
3.3 Geometric definitions
Note: See Figure A.1 of Appendix A.
3.3.1
Reference center
A point on or near a retroreflective surface which is designated to be the center of the device for the purpose of specifying its performance.
3.3.2
Illumination axis
A line segment from the reference center to the light source.
3.3.3
Observation axis
A line segment from the reference center to the photometer head.
3.3.4
Observation angle (symbol a)
a
The angle between the illumination axis and the observation axis. The observation angle is always positive and, in case of retroreflection, is restricted to small angles. Maximum range: 0≤a≤80°.
3.3.5
Observation half-plane
The half plane which originates on the illumination axis and which contains the observation axis.
3.3.6
Reference axis
An axis originating on the reference center which is used to describe the angular position of the retroreflector.
3.3.7
Entrance angle (symbol β)
β
The angle from the illumination axis to the reference axis. The entrance angle is usually not larger than 90°, but, for completeness, its full range is defined as 0≤β≤180°. The orientation of β is determined by two components, β1 and β2.
3.3.8
First axis
An axis through the reference center and perpendicular to the observation half-plane
3.3.9
First component of the entrance angle (symbol β1)
β1
The angle from the illumination axis to the plane containing the reference axis and the first axis. Range: -180°<β1≤180°.
3.3.10
Second component of the entrance angle (symbol β2)
β2
The angle from the plane containing observation half plane to the reference axis. Range: -90°≤β2≤90°.
