ASTM E1709-09 Method for Measurement of Retroreflective Signs

ASTM E1709-09 test method is used to perform measurement related to the brightness of retroreflective traffic signs approximately facing the driver at night time by using a mid-sized automobile equipment with tungsten filament headlights at about 200 m distance. The quality of the traffic signs as to material used, age, and wear pattern will affect the coefficient of retroreflection. These conditions are observed and noted by the user.

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Scope:

The ASTM E1709-09 method covers measuring the retro-reflective properties of sign materials such as traffic signs and symbols (vertical surfaces) using a portable retro reflectometer at a 0.2-degree observation angle that can be used in the field. The portable retro reflectometer is a hand-held instrument with a defined standard geometry that can be placed in contact with sign material to measure the retroreflection in a standard geometry.

Test Procedure:

The ASTM E1709-09 test method involves commercial portable retroreflectometers to determine the retroreflectivity of highway signing materials. The entrance angle shall be -4°. The observation angle shall be 0.2°. The portable retroreflectometer uses an instrument standard for calibration. After calibration, the retroreflectometer is placed in contact with the sign to be tested, ensuring that only the desired portion of the sign is within the measurement area of the instrument. The reading displayed by the retroreflectometer is recorded. The retroreflectometer is then moved to another position on the sign, and this value is recorded. A minimum of four readings shall be taken and averaged for each retroreflective color or material on the sign to be tested.

Test Specimen:

Retroreflective materials used on traffic signs are tested using the ASTM E1709-09 test method.

Data:

When measuring molded prismatic signs composed of optical elements with an average diameter greater than 1 mm, using a standard of similar composition is preferable. If the standard used is composed of retroreflective sheeting, then the instrument readings shall be multiplied by the following correction factor:

d is the average diameter of the sign’s optical elements, and D is the diameter of the instrument’s measuring area.

Conclusion:

ASTM E1709-09 provides details about a test method for measuring the retro-reflective properties of sign materials, such as traffic signs and symbols (vertical surfaces), using a portable retro-reflectometer.