Retroreflectivity
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Retroreflectivity Measurement:

lasphoto.jpg (62264 bytes) Laserlux® is an automated real time pavement marking retroreflectivity measurement tool, marketed by Roadware Corp,and is patented by Potters Industries.
The retroreflectometer sends a laser beam which is retroreflected by glass beads embedded in the paint of the pavement marking.
laser.jpg (30811 bytes) The retroreflectometer uses a scanning laser beam at 1/3 scale geometry to scan the pavement marking roughly 32000 times per hour, while travelling at highway speeds, under all ambient light conditions, using either the North American or European standard geometry's.
The laserlux software©, uses the QNX™ real time operating system to facilitate approximately 9 stripe measurements per second, consisting of 200 sampling points for each measurement, with an incoming data frequency of approximately 100 MHz during each measurement. In real time, (9 times per second) the laserlux software identifies the stripe within a 1m scan width, calculates the peak retroreflectivity, displays it to the user console, and retains the retroreflectivity measurement. Over the distance of a user selected station interval, the mean retroreflectivity is reported, as well as the variability. The user video console display can be superimposed on a video image of the actual stripe being measured. Optionally, event codes for different conditions can be entered by keyboard, and become part of the record.

 

At the end of the data collection sequence, the average retroreflectivity is summarized by station averages for left and right stripes and average value (for double pavement marking lines).

REFERENCES:

Maerz, N. H., and Swindall, B., and Davies, C., 1999. Automated real time pavement marking retroreflectivity measurements. Presented at the Transportation Research Board, 78th Annual Meeting, Jan 10-14, 1999.

® Laserlux is a registered trademark of Potters Industries.

© Laserlux software, copyright Roadware Corporation.

® QNX is a registered trademark of QNX Software Systems Limited