Trajectory deflection influence on the performance of roundabouts.

Author(s)
Bastos, S.A. & Seco, A.
Year
Abstract

It is widely accepted that the use of a well designed roundabout usually results in significant changes to driver behavior and in a sizable reduction of approaching and crossing of speed profiles. These facts broadly explain the considerable reduction on accident levels of this type of intersection when compared with other solutions. However the influence of some geometric aspects on drivers' behavior, speeds and trajectories is not well known. These issues become especially relevant in multiple lane roundabouts since they offer the driver a greater freedom of movements which can cause inappropriate behaviors. On the other hand it is commonly accepted that the performance level of a roundabout depends largely on its design and particularly in its potential ability to physically restraint driver behavior inducing him to naturally adopt correct behaviors without contradicting his natural expectancies. Recent investigation shows that design solutions with low levels of deflection tend to have low performance levels with very heterogeneous speed profiles. Because they are uncomfortable high deflection designs induce the driver to invade the adjacent lane while searching for more direct and comfortable trajectories. The present paper presents some results included on the PHd thesis and identifies empirical relations between drivers' behavior and the geometric characteristics associated with movement deflection therefore contributing to the understanding of the relationship between these parameters and the speeds and trajectories adopted by drivers.tional experience and on observations carried out on a set of twenty circuits that had a reasonable variation in their geometric design parameters but within an acceptable range according to specialized technical documents. The data collection sessions were supported by an instrumented vehicle which had equipments to measure driver's actions on the vehicle's commands its dynamic response. A set of fourteen young and homogeneous drivers were used for behavior observation. The presented results show the speed and the trajectories analysis traced for each driver while negotiating and crossing the roundabout and its correlation with some of the deflection design parameters. Finally some design criteria's are presented on identifying suitable value ranges for deflection that induce correct driver behavior. For the covering abstract please see ITRD E135207.

Request publication

2 + 9 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.

Publication

Library number
C 43127 (In: C 42993 CD-ROM) /85 / ITRD E135352
Source

In: Proceedings of the European Transport Conference ETC, Strasbourg, France, 18-20 September 2005, Transport Policy and Operations - Traffic and Transport Safety - Safe Road Design. 2005. 15 p., 5 ref.

Our collection

This publication is one of our other publications, and part of our extensive collection of road safety literature, that also includes the SWOV publications.