Comparison of the highway safety manual predictive method with safety performance functions based on geometric design consistency

Abstract

Road safety is a major public health concern in our society. Effective road design and accurate safety analyses must be a component of programs focused on reducing and eliminating roadway injuries and deaths. Various methodologies exist to determine the expected number of crashes on rural two-lane rural roads. This research compares different procedures which allow for the estimation of the number of crashes on homogeneous road segments. In this effort, a total of 27 two-lane rural road sections located in North Carolina were considered, resulting in 59 homogeneous road segments composed of 350 horizontal curves and 375 tangents along 150 km of road. Four methods were applied to the selected roadways: the HSM predictive method, two jurisdiction-specific Safety Performance Functions (SPFs), and a SPF which includes a consistency parameter. This research found that the use of SPFs which incorporate a consistency parameter allows highway engineers to consider human factor impacts on road safety assessment. The use of a consistency parameter can also simplify the crash estimation process. Analysis methods which only included local geometric variables provided unreliable results due to the calibration of only the specific road elements instead of their relationship with other road elements along homogeneous road segments.

Accident risk analysis of road geometric components using functional worthiness approach

“…The geometric design of roads in mountainous areas is certainly not easy to comply with technical requirements. This is due to land limitations and topographic conditions that are not flat [8]. This opinion follows what has been expressed that inconsistent geometric design in mountainous areas with technical requirements will have a high accident risk [9].…”

“…Previous studies show evidence that various aspects need to be considered to realize road traffic safety. Improving safety performance needs to pay attention to the geometric aspects of the road [8], the existing spatial conditions of the terrain [9], and the behavior of road users [10]. This is very relevant to the importance of road safety because of the factors that cause accidents even though they are caused by various factors [11], but the geometric aspect is very important [12].…”

Safety Evaluation for Highway Geometric Design Based on Spatial Path Properties

“…Interactive highway safety design model (IHSDM) is a typical application that provides a policy review module to compare roadway segment geometry to pertinent design policy [14]. It was discovered that the evaluation of highway geometric design consistency checks is an important issue in design and trafc operation evaluation [15]. Because only considering separated indexes that meet design standards does not guarantee the alignment fuidity and safety of the highway, the coordination research on horizontal and vertical alignments is a critical procedure that should commence with a preliminary design in order to be easily adaptable.…”

Modelos de velocidad de operación de carreteras rurales en terreno llano en Costa Rica

“…En los últimos años, en muchos países se ha evaluado la seguridad vial a partir del análisis de la consistencia del trazado (Abebe & Belayneh, 2018;Almeida et al, 2018;Echaveguren et al, 2020;Fitzpatrick et al, 2000;García et al, 2012;Kiran et al, 2017;Li et al, 2017;Llopis-Castelló et al, 2020;. El análisis de la consistencia del trazado permite verificar si las condiciones geométricas de la carretera generan pequeños diferenciales de velocidad entre elementos consecutivos, ya sea curvas y rectas en horizontal o acuerdos, tanto cóncavos como convexos.…”