The Evasion Diameter and Effective Domain for Crossing

Abstract

The evasion diameter for vessels going either in the same direction or in the opposite direction has been well studied. Here, one year long survey was performed on marine traffic in the Bisan Seto to obtain the evasion diameter for crossing vessels which is very important for the estimation of the traffic capacity of crossing area. The result of observation from the bridge of Daisan Ukomaru, a ferry navigating in North-South route, yielded (1) the density of vessels either east bound or west bound to be about 2.4 per square miles, and (2) average number of evasive motions per one crossing to be 1.15. The evasion diameter for crossing was calcualted using above values and the average speed and it is about 12L where L is the average length of vessels. More detailed analysis gave (11.5±1.5) L for the diameter.