Analysis of TXDOT Thickness Measurement Procedures for Thermoplastic Pavement Markings

摘要

Research has shown that thickness plays a major role in the retroreflective performance of thermoplastic pavement markings, especially on newly sealcoated roadway surfaces. Therefore, accurate thickness measurement by inspectors on striping jobsites is necessary to ensure adequate thickness is being achieved. This report presents the results of a statistical analysis comparing two thickness measurement methods for thermoplastic pavement markings that are commonly used by Texas Department of Transportation (TxDOT) inspectors. These two methods are: (1) measure thickness of thermoplastic pavement marking sample with a standard laboratory caliper and (2) measure thickness of thermoplastic pavement marking sample with a needlepoint micrometer. The main difference between the two measurement methods is the accuracy of the instrument. The needlepoint micrometer allows for accurate measurement to the top of the binder material, while it is very difficult to get a measurement to the top of the binder material with a caliper. Therefore, caliper measurements are often made to the top of the drop-on beads. Current TxDOT policy states that thermoplastic thickness be specified and measured to the top of the binder material.