Parameters to define road design speeds on rolling terrain Parámetros que definen la velocidad de diseño de carreteras en terreno ondulado

Abstract

In Colombia, the number of fatal crashes is evidence of a road safety problem, and geometric design consistency could be a solution to reduce them, since they are directly related. The Colombian Highway Geometric Design Manual aims to address consistency at an early stage of design through the assignment of specific speed for plan and profile elements. The objective of this study is to verify the applicability of the parameters that define this velocity in horizontal curves for undulating terrain. Forty horizontal curves were analyzed in which 1380 speed data were recorded with users circulating at free flow. Geometric and operational elements were considered as independent variables, and speed changes as dependent variables. The multifactor analysis of variance performed on a group of categorized variable combinations determined that the design speed is most sensitive to the operating speed parameter on the previous curve (Voi-1) with R2 coefficients between 63% and 75%, and to the geometric parameter deflection angle (Δ) with R2 coefficients of determination between 43% and 56%. It is concluded that the Highway Geometric Design Manual requires methodological changes in the assignment of specific speeds and a new methodology is proposed for the assignment of specific speeds for undulating terrain.