Coordination of horizontal and sag vertical curves on two-lane rural roads: Driving simulator study

Abstract

a b s t r a c t a r t i c l e i n f o Available online xxxxThe highway geometric design guidelines for several countries provide suggestions for the coordination of horizontal curves overlapping with sag vertical curves (sag combinations) to avoid combined configurations that produce undesirable optical effects and reduced safety. Such suggestions are derived from studies based on the drawing of the perspective of the road. This drawing method is severely limited with respect to the simulation of the perspective view of the highway to the driver during the dynamic task of driving. Interactive driving simulation methods are deemed to be more efficient for these objectives. This paper reports the results of a study carried out using an interactive driving simulator to evaluate the effects on the driver's speed behavior of different configurations of sag combinations and non-combined curves on a flat grade with the same features as the horizontal curves of the sag combinations (reference curves). The speed behaviors of drivers along the tangent-curve transitions of sag combinations and reference curves were recorded. The speed on the approach tangent, the speed at the midpoint of the horizontal curve and the maximum speed reduction (MSR), the difference between the maximum speed on the last 200 m of the approach tangent and the minimum speed on the first half of the horizontal curve, were analyzed. One-way repeated MANOVA was performed to determine if the driver's speed behavior on the horizontal curves was influenced by different configurations of sag combinations and reference curves. The primary result was that on suggested sag combinations, the driver's speed behavior did not differ in any statistically significant way from that on the reference curves. Whereas the critical sag combinations (configurations that should be avoided) caused high values of maximum speed reduction along the tangent-curve transition, which pointed to the driver's reaction to an incorrect perception of the road alignment. Therefore, this result confirmed the effectiveness of the road design guidelines for the coordination of horizontal curves and sag vertical curves.

The use of GIS tools for road infrastructure safety management

“…20 % of all fatalities being the result of run-off-road accidents, mitigating this hazard becomes a priority. Horizontal curves and their parameters have a strong impact on road safety [24] [29]. Horizontal curves are strictly related to speed and visibility [30].…”

Symulacje Numeryczne Stalowej Bariery Ochronnej Na Łuku Drogi

“…Wyniki badań tego zagadnienia [1,2,3] sugerują, że bezpieczeństwo związane z poruszaniem się po łukach poziomych wynika z trzech powiązanych ze sobą kwestii: zaburzenie uwagi kierowcy, niedostosowanie prędkości do krzywizny oraz niewystarczająca szerokość pasa jezdni. Kolejnym ważnym czynnikiem uwzględnianym w badaniach jest stan nawierzchni w obrębie łuków poziomych [4].…”

Effect of Motion Cues on Highway Driving Performance in Simulated Driving

“…In China, driving simulators are recommended as tools by the country's Specifications for Highway Safety Audit, especially for roads with complex terrain (3). In many studies (4)(5)(6)(7), driving simulators are used to evaluate combined alignments and roadside design safety, and an increasing prevalence of highway design safety evaluation using a driving simulator is observed.…”

“…The DOF of a motion system is very important for experimental validity. The motion system may influence driver speed (7,8), acceleration (7,9), and lane deviation (10,11). A series of studies investigated the relationship between these driving performance variables and combined alignments using driving simulators (5,7,11), which showed that these variables were vital for highway design safety evaluation.…”

“…The motion system may influence driver speed (7,8), acceleration (7,9), and lane deviation (10,11). A series of studies investigated the relationship between these driving performance variables and combined alignments using driving simulators (5,7,11), which showed that these variables were vital for highway design safety evaluation. But few studies have analyzed the influence of a motion system on multiple driving performance variables, so it is necessary to explore comprehensively how motion cues affect driving performance during simulated driving.…”