RetroSign GR1 & GR3 · Retroreflectometer
5
Section 1 – Introduction
RetroSign introduction
The RetroSign Retroreflectometer is a portable field instrument intended for measuring the retroreflection properties of
road signs in car headlight illumination. The value R
A
(coefficient of retroreflected luminance) is used for the measure-
ment. R
A
is a measure of the visibility
of the road signs as seen by drivers of motorized vehicles in headlight illumination.
The RetroSign is available in different versions.
For type GR3 ASTM the sign is illuminated at an entrance angle of -4º and the measurements are made with angles be-
tween illumination and observation of 0.2º, 0.5º and 1.0º. This is relevant for a motorist viewing situation under normal
conditions.
For type GR3 CEN the sign is illuminated at an entrance angle of +5º and the measurements are made with angles be-
tween illumination and observation of 0.33º, 0.5º and 1.0º. This is relevant for a motorist viewing situation under normal
driving conditions.
For type GR1 SAFETY the measurement area is illuminated at an entrance angle of +5º and the measurements are
made with an observation angle of 0.2º, angles used to measure Safety Clothing according to EN 471
The ASTM and CEN type instruments is also offered in a GR1 version with only the primary observation angles of 0.2º
(ASTM) and 0.33º (CEN).
The range of RetroSign instruments available are summarized below:
ASTM
CEN
Safety
RetroSign GR1
√
√
√
1 primary observation angle
RetroSign GR3
√
√
3 observation angles
Geometry
ASTM E 1709
EN 12899-1
EN 471
R
A
is an important factor in the onsite quality control of road signs.
DELTA RetroSign Retroreflectometer.
The operation of the Retroreflectometer is very simple and requires a minimum of instruction. An error or warning mes-
sage is given in case of unreliable or measurement.
