The use of portable retroreflectometers to evaluate the reflectivity of longitudinal markings such as center lines and edge lines, and special markings such as arrows and symbols is described. Two hand-held retroreflectometers (ecolux and mirolux 12) were used in these evaluations. Retroreflectometers measure reflectivity of pavement markings through manual placement on a small section of pavement marking. The mirolux 12 unit was used for most readings because it is easier to operate and speeds data collection. Two evaluation procedures were used. The first procedure evaluated longitudinal pavement markings and involved selecting a section of pavement markings (usually 1 to 3 mi long), breaking that section down into zones, and takingreflectivity readings within those zones. The second procedure evaluated special markings and involved taking 5 to 10 reflectivity readings for each marking to determine the reflectivity level for each marking. The use of retroreflectometers with these evaluation procedures has proven to be a helpful tool for the traffic engineer in evaluating the nighttime performance of pavement markings. Thermoplastichas been used in north carolina since the mid-1970s and has long been considered a durable pavement marking; however, objective evaluations of its reflective performance have never been made. An in-service evaluation was performed on nearly 350 mi of thermoplastic long lines using portable retroreflectometers. This evaluation indicated that thermoplastic is both a durable and a reflective pavement marking. Another evaluation raised questions about reflectivity during deck testing of preformed tapes. These questions led to an in-service evaluation of approximately 200 special markings. The evaluation indicated poor reflectivity performance of preformed tapes. This paper appears in transportation research record no. 1230, Work-zone trafficcontrol and tests of delineation material.
Samenvatting