Are driving and overtaking on right curves more dangerous than on left curves?

Download
Sarbaz Othman
Robert Thomson
Gunnar Lannér

It is well known that crashes on horizontal curves are a cause for concern in all countries due to the frequency and severity of crashes at curves compared to road tangents. A recent study of crashes in western Sweden reported a higher rate of crashes in right curves than left curves. To further understand this result, this paper reports the results of novel analyses of the responses of vehicles and drivers during negotiating and overtaking maneuvers on curves for right hand traffic. The overall objectives of the study were to find road parameters for curves that affect vehicle dynamic responses, to analyze these responses during overtaking maneuvers on curves, and to link the results with driver behavior for different curve directions. The studied road features were speed, super-elevation, radius and friction including their interactions, while the analyzed vehicle dynamic factors were lateral acceleration and yaw angular velocity. A simulation program, PC-Crash, has been used to simulate road parameters and vehicle response interaction in curves. Overtaking maneuvers have been simulated for all road feature combinations in a total of 108 runs. Analysis of variances (ANOVA) was performed, using two sided randomized block design, to find differences in vehicle responses for the curve parameters. To study driver response, a field test using an instrumented vehicle and 32 participants was reviewed as it contained longitudinal speed and acceleration data for analysis. The simulation results showed that road features affect overtaking performance in right and left curves differently. Overtaking on right curves was sensitive to radius and the interaction of radius with road condition; while overtaking on left curves was more sensitive to super-elevation. Comparisons of lateral acceleration and yaw angular velocity during these maneuvers showed different vehicle response configurations depending on curve direction and maneuver path. The field test experiments also showed that drivers behave differently depending on the curve direction where both speed and acceleration were higher on right than left curves. The implication of this study is that curve direction should be taken into consideration to a greater extent when designing and redesigning curves. It appears that the driver and the vehicle are influenced by different infrastructure factors depending on the curve direction. In addition, the results suggest that the vehicle dynamics response alone cannot explain the higher crash risk in right curves. Further studies of the links between driver, vehicle, and highway characteristics are needed, such as naturalistic driving studies, to identify the key safety indicators for highway safety.

MEET US


25-26
Apr

Cost Benefit Analysis (CBA) workshop in Stockholm

An open seminar and workshop in Stockholm will be held on 25-26 April 2018. The workshop deals with the use of CBA as a basis for decision-making in the public sector. The workshop is organized by, among others, Professor Jan-Eric Nilsson, VTI.

LATEST NEWS


2018-02-19

Modal shift for an environmental lift?

Investigations in Sweden and other countries suggest a shift of goods transport from road to rail and waterborne transport to reach environmental and climate objectives. VTI is leading a new project to investigate how the modal shift can contribute and what...


2018-02-13

Automation and digitalisation are making rail competitive

Road transport is developing rapidly and its productivity has increased sharply. Rail transport, however, has not developed at the same rate. Automation and digitalisation are essential if rail freight in Europe is to survive.


2018-02-08

New research is creating a driverless logistics chain

The research project Born to Drive has come up with a system that allows new cars to move, without a driver, from the production line out to the parking area prior to being transported elsewhere. The vision is to automate the entire logistics chain from...


2018-02-05

VTI testing automation in EU project

VTI is leading a series of tests in a major EU project on automated driving. The first driving tests were carried out n a test track in Slovenia in December. The project will focus in part on acceptance among different groups in society, in part on...


2018-02-02

Freight transportation on road and rail analysed

Freight transport accounts for a large proportion of the emissions, noise and congestion produced by road traffic. Transporting freight in larger but fewer lorries could reduce the problem. At the same time it might entail freight being diverted from more...


2017-11-30

Millions for research into maritime transport and the environment

Maritime transport is a major source of emissions of harmful air pollutants and carbon dioxide. In a new project, a research team from the Swedish National Road and Transport Research Institute (VTI) and the University of Gothenburg has received SEK 6.4...