01004413

Component

Many road standards encourage or require the use of the spiral curve in the transition section of the horizontal curve. However, it is not clear if its use has any beneficial effect on traffic safety. Very few studies have analyzed the effect of the spiral curve on accident rate but even then results differ and, in certain cases, even conflict. In particular, some of these results seem to show the potentially negative effect of a long spiral on the driver's curve perception and on safety. The objective of this research was to verify if the presence and the length of spiral curves affect driver behavior. Research focused attention on car paths along transition sections with and without spiral transitions. Car paths were surveyed using a digital video camera. Research involved the study of 6 spiral transitions and 6 direct tangent-to-circular curve transitions on two-lane rural roads. Different driver behaviors were analyzed comparing car paths along transition sections with spirals of different lengths and along transition sections without spirals. Results show a clearly negative effect of the spiral length on driver behavior only if the spiral is longer than the distance traveled during natural steering time. On the contrary, when these lengths are similar, there is no evident difference between driver behavior along the transition sections with or without spiral curves.

01004374

English

23p

2005

3rd International Symposium on Highway Geometric Design

CD-ROM

Figures (8) ; Photos (1) ; References (18) ; Tables (3)

Behavior; Crash rates; Digital video; Geometric design; Highway design; Rural highways; Spirals; Traffic safety; Two lane highways

Horizontal curvature; Transition sections (Curves); Vehicle path

Design; Highways; I20: Design and Planning of Transport Infrastructure

TRIS, TRB, ATRI

Sep 29 2005 10:54AM