Selecting Speed Limits for Multilane Highways with Curbs and Gutters

摘要

Most states discourage the use of curbs on roadways with design or operating speeds greater than 45-mph.The research herein assesses current practices used to determine correct speed limits when widening two4lane highways with 55-mph speed limits to multilane highways with curb and gutter cross-sections. Theresearch also recommends enhanced design standards and speed limit guidelines. A number of relatedtasks have been encompassed. The speed studies were conducted at 32 sites that had recently beenupgraded from two-lane roadways to four- or five-lane roadways with curb and gutter profiles. The speedvariances and speeding rates at these sites were examined and compared to corresponding data fromsimilar sites on two-lane roadways. A series of human factors studies that used the DS-600c drivingsimulator system at the University of Tennessee was conducted to assess the effects of curb and gutterprofiles and posted speed limits on driver speed selection. In addition, a study of the effects of speedlimits, in combination with curb and gutter, on crash rates was performed utilizing crash data from theHighway Safety Information System (HSIS). Based on the research findings, study authors recommendthat traffic agencies develop an alternative design standard for use on transitional roadways as defined inthis research. The alternative standard would allow the use of design speeds and posted speed limits inexcess of 45-mph, along with the use of correctly sloping curbs, on this new category of roadways.