A critical issue associated with the retroreflectivity of pavement markings is the ability to measure retroreflectivity. Most pavement markings are manufactured on-site, and it is not practical to remove a pavement marking so that the retroreflectivity can be measured with a high level of accuracy. Instead, agencies and contractors rely on portable retroreflectometers to measure the retroreflectivity of pavement markings.

Portable pavement marking retroreflectometers have been available for many years. Pavement markings are currently measured according to 30-meter geometry, which represents retroreflectivity at a distance typical of that which drivers view markings. Pavement markings were previously measured at 15-meter geometry, and no simple conversion exists between 15- and 30-meter measurements. Retroreflectometer geometry is described in further detail in ASTM E 1710. Contact TxDOT’s Materials Laboratory for a description of approved retroreflectivity measurement devices. Note that different manufacturers’ retroreflectometers will produce different retroreflectivity values for a given stripe, and no accurate conversion factor exists.