E.R.M.A.: a Retro-Reflectivity Device: Preliminary Report 1974

The Physical Research Section of the Minnesota Department of Highways has developed and constructed a device to measure the retro-reflective characteristics of pavement marking materials. The device can be operated at highway speeds and during normal daytime working hours with a minimal disruption to traffic.

The device is a useful research tool and has been used mainly in this capacity. However, with the recent increase in materials cost of pavement marking and the reduced availability of these materials, ERMA can and should be used as a maintenance management tool. This will enable us to paint when it is necessary rather than according to a time schedule.

This is only a portion of the final report and is not intended to give a complete description of the development of the device and proof that it works and results are repeatable. The complete final report will show the data which was obtained and prove the value of the device.

This report is intended to show how the device is constructed and operated and a description of the method used to correlate the device to what drivers observe as reflectivity level under nighttime driving conditions.