Reinforced concrete structures in ports and harbours are exposed to severe environments in terms of chloride induced deterioration. It is well known that the progress of chloride induced deterioration in the superstructure of open-type wharf varies widely due to many factors such as seawater levels and location of structural members. The aim of this study is to evaluate the influence of these factors on the deterioration progress and detect the area where it becomes relatively faster. In this study, two statistical approaches were carried out to discuss the variability of the deterioration progress not only in the superstructure of open-type wharves but also in structural members; 1) statistical analysis on the visual inspection data of the superstructure of 19 open-type wharves, and 2) measurement of chloride ion content and estimation of its spatial distribution.
The main results of this study were following;
 The deterioration of horizontal beams, which is parallel to the longer direction of the open-type wharf, was progressive at sea side and land side. The deterioration of vertical beams, which is perpendicular to the longer direction, was progressive when the distance between H.W.L. and the bottom surface of beams was close. The deterioration of slabs was less progressive at land side whereas it was progressive when the tidal variation was small.
 The surface chloride ion contents of two slabs were significantly different and one of them varied widely. However, the results of the estimation of the spatial distribution of the surface chloride ion content of two slabs had a similar spatial distribution; the surface chloride ion content at the rear side of a slab was high and that at the middle and the front side of a slab was low.
From these results, in this study, the areas where the progress of deterioration is relatively faster are parallel beams and slabs at the sea side and beams at the land side of the open-type wharf.

Key Words: Superstructure of open-type wharf, chloride ion induced deterioration, deterioration progress, survival analysis, spatial statistics