Traffic jams caused by repair work at night on the Expressway are seen even less traffic flow than that of the capacity. This study is to develop the model which explains vehicle merging behavior at the regulated area on the basis of data derived from microscopically traced trajectory of vehicles. The specified points of the study is as follows: (1) vehicle merging behavior is composed of preparatory and adjusting behavior, (2) during the preparatory behavior, decision of merging is being made time to time until the merging is successful, (3) therefore a disaggregate type modelling is applied to the vehicle merging behavior.