Author(s)

G. Gjetvaj

Abstract

Bora is a local, changeable wind that significantly decreases traffic security on the Zagreb-Split motorway on the south side of the Velebit Mountain. On the road section tunnel Sv. Rok - knot Posedarje, the wind velocity increases from near zero in tunnels up to wind gusts of 69 m/s near the bridges. The incoming wind direction varies from parallel to perpendicular to the road axes. As a result of such meteorological conditions, some incidents occur. For that reason the motorway has often been closed to certain categories of vehicle, or even to all traffic, during periods of strong wind. The goal of the described project was to design windbreaks that would decrease wind force and moment acting on the vehicles in such a way that the side wind does not exceed the prescribed value. In this paper a new procedure for homogenization of driving conditions when wind direction and intensity change significantly was developed. Four different types of windbreaks are proposed, based on the results of computer simulation and wind tunnel tests. The proposed windbreaks will significantly increase safety on the motorway during strong Bora. Keywords: windbreaks, driving conditions, Bora. 1 Introduction The newly built section of the motorway Zagreb-Split from the St. Rok tunnel to the Posedarje knot passes through the southern slope of the Velebit in the area where gale-force Bora often occurs with the strongest measured squalls of 69 m/s (248 km/h). Bora endangers traffic safety so the motorway is frequently

Keywords

windbreaks, driving conditions, Bora.