There is a need for a portable retroreflectometer which can perform reflectivity measurements in the field . This could eliminate the need for subjective ratings or taking samples of materials from the field to test in the laboratory. This report describes the development of a portable retroflectometer (PRR).

A PRR was built with the objective of approximating the angles of incidence and divergence used in the ESNA Reflex-Photometer (ESNA). Tests showed a good relationship between readings taken with the PRR and ESNA. The recommendation was made that the PRR is suitable for use as a means of measuring reflectivity in the field. However, the PRR should be used concurrently with subjective ratings and future modifications, with the objective of improving measurement consistency, are warranted.

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