This report describes a study of the delineation requirements for work zone traffic control. The research included a comprehensive review of past studies and current practices, and an examination of current standards. It was concluded that, in spite of the increasing number of different types of channelizing devices, there appears to be no scientific basis for the spacing criteria for the use of devices for channelization purposes in the taper or tangent sections of a work zone. A laboratory-based testing procedure was used to determine the most appropriate spacing configuration. An interactive video system was used to test subject recognition distances of eight different device types spaced at the standard distance, 1.5 times and 2.0 times the standard distance. Over 240 subjects were tested. The results indicated variability between the performance of most channelizing devices across the spacings tested. Field testing was undertaken at six actual work zones. Right and left closures were used to test the various device-spacing configurations under both day and night conditions. Manual and automated methods were used to gather the field data for traffic approaching a work zone. The study area included four points equally spaced over the 2000 ft (600 m) before the work zone and the activity at the start of the taper for the lane closure. The tests were undertaken under the hypothesis that the most effective treatment would minimise the percentage of traffic in the closed lane at the start of the taper. Field data were analysed for 2100 5-minute observation periods. Statistical analysis of the data determined neither type of device (round barrels, oblong barrels, Type II barricades, and cones with reflectorized collars) or device spacing (55, 80, and 110 ft) (16.5, 24.7, and 33.0 m) had a significant effect on driver lane changing behaviour. Recommendations for locating work zones to maximise the sight line on the approach to the taper are presented. (A)
Abstract