The Texas A&M Transportation Institute (TTI) has developed and conducts various programs and guidance documentation related to the evaluation of pavement markings and traffic signs.
Mobile Retroreflectometer Certification Program
The mobile retroreflectometer certification program evaluates the ability of a mobile pavement marking retroreflectivity provider to accurately evaluate pavement marking retroreflectivity. The operator of the equipment and the equipment itself are evaluated. Certification is required prior to collecting data on Texas Department of Transportation (TxDOT) projects.
Retroreflectivity Verification Program
The retroreflectivity verification program evaluates the accuracy of provider collected mobile pavement marking retroreflectivity data on jobs for TxDOT. The provider data is compared to data TTI collects on the same markings within a short timeframe of the provider data collection. Accurate field verification checks are required for the provider to maintain mobile retroreflectometer certification. TTI only verifies the accuracy on a portion of provider jobs. Each District should also monitor contractor performance.
Mobile Pavement Marking Retroreflectivity Guidance
The mobile pavement marking retroreflectivity guidance presentation was developed to provide a resource to help improve the understanding of mobile pavement marking retroreflectivity data collection and the related TxDOT standards and specifications. The guidance was developed to provide information to TxDOT personnel who are involved with mobile pavement marking retroreflectivity, but may also be beneficial to providers of mobile retroreflectivity data. The guidance describes the requirements in TxDOT Item 666 – Retroreflectorized Pavement Markings and the Special Specification for “Mobile Retroreflectivity Data Collection for Pavement Markings.” The guidance provides an overview of the mobile retroreflectivity certification and verification programs. The guidance also provides an overview of the data output from the various mobile retroreflectometer systems and how the data should be analyzed.
Wet Retroreflectivity Measurement Guidance
Continuous wet retroreflectivity measurements are more complicated than dry retroreflectivity measurements. The requirements for the continuous spray application to simulate the rainy condition add another process that needs to be calibrated and conducted properly to achieve accurate and consistent retroreflectivity values. TTI has developed guidance material to support the evaluation of wet-weather pavement marking retroreflectivity. The guidance covers all aspects of the measurement process, including the equipment, calibration, setup, measurement techniques, and best practices. A summary field guide and a short video were developed to support the guidance material. The field guide can be used as a simple document to reference while in the field taking measurements. The video provides examples of how to calibrate the equipment and how to conduct the measurements. TTI also provides a spreadsheet tool to assist with calibration of the continuous wetting device.