Examining the Influence of Speed Limits for Multilane Highways with Curbs and Gutters

This research assesses the current practices used to determine the correct speed limits when widening two-lane highways with $88.51\hspace{0.17em}\mathrm{k}\mathrm{m}/\mathrm{h}\hspace{0.17em}(55\hspace{0.17em}\mathrm{mi}/\mathrm{h})$ speed limits to multilane highways with curb and gutter cross sections. A number of related tasks have been encompassed in this study. The speed studies were conducted at 32 sites that had recently been upgraded from two-lane roadways to four or five-lane roadways with curb and gutter profiles. The speed variances and speeding rates at these sites were examined and compared with corresponding data from similar sites on two-lane roadways. Apart from the field test study, a series of human factor studies that used the DS-600c driving simulator system at the University of Tennessee was conducted to assess the effects of curb and gutter profiles and posted speed limits on driver speed–selection behaviors. In addition, a study of the effects of speed limits, in combination with curb and gutter, on crash rates was performed using crash data from the Highway Safety Information System (HSIS). Based on the research findings, the study authors recommend that the alternative standard that allows the use of designed speeds and posted speed limits in excess of $72.42\hspace{0.17em}\mathrm{k}\mathrm{m}/\mathrm{h}\hspace{0.17em}(45\hspace{0.17em}\mathrm{mi}/\mathrm{h})$, along with the use of correctly sloping curbs, should be developed by the traffic agencies.