The National Academies

NCHRP IDEA 20-30/IDEA 146 [Completed (IDEA)]

Advanced Methods for Mobile Retroreflectivity Measurement on Pavement Marking
[ NCHRP 20-30 (NCHRP-IDEA) ]

  Project Data
Staff Responsibility: Dr. Inam Jawed
Fiscal Year: 2009

This project was aimed at developing and demonstrating the use of a prototype mobile unit for a rapid and reliable measurement of pavement marking retrorefletivity. The work involved designing and building a prototype laboratory unit capable of measuring retroreflectivity from sample strips. The unit consisted of a retroreflectivity measurement system, tracking system, geometry measurement system, neural network system, and speed simulator system. The unit was assembled from component systems and tested for measuring retroreflectivity on a sample strip at simulated highway speeds. The repeatability of the measurement was satisfactory, and the tests showed close correlation between hand-held and mobile units under stationary conditions.  Work in Stage 2 involved testing the mobile retroreflectivity unit mounted on a vehicle. The tasks included designing and building the mounting mechanisms, selecting electrical power source and control, refining methods to handle real time road and environmental conditions, and developing calibration procedures. A real time tracking system was added to the mobile unit to handle various road conditions and was further refined. Two more lasers were also added to the system to identify the geometry positions in a more consistent and reliable manner. The transition from the laboratory unit to the mobile unit under road conditions was challenging and required many iterations of refinements. However, the technical issues were resolved, and work continued on measuring retroreflectivity at a selected test site and comparing results with measurements using a handheld unit. The latest road results show the repeatability error to be at about 1.5%. While comprehensive data on measurement accuracy in road tests is not presently available, the initial accuracy tests indicate the results to be within the design expectation of 10%. A new production version of the system was designed for further testing with a goal for implementation and commercialization.  The contractor's final report is available.

To create a link to this page, use this URL: http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=2856