A study was made to determine whether the more expensive wide edgelines are cost beneficial in terms of reducing edgeline-related accidents. A separate and limited evaluation was also conducted to determine the effects of 4-in and 8-in edgelines on drivers' performance in an uncontrolled environment. Within the curve, the measure of performance was the frequency of encroachment (i.E., Tires touching or going over) either the centerline, edgeline, or both. It was foundthat 8-in edgelines are not cost effective for installation on 2-lane rural roads in those areas where there is frequent heavy snowfalland the use of deicing materials and abrasives tends to deteriorateedgelines, or where pavement widths are less than or equal to 22 feet. They are also not cost-effective where roads have paved shoulders over 6 ft wide. It is noted that 8-in edgelines may be appropriateas a safety improvement when applied at spot locations such as isolated horizontal curves and approaches to narrow bridges.
Abstract