This paper deals with the study of a signal control system along the route 2 in Hiroshima city from the viewpoint of a digital control for traffic flow dynamics. Time-varying characteristics of traffic flows are analyzed to evaluate the volume balance at each signalized intersection during the cycle length for each lane. The signal control system of the congestion length is described by a nonlinear time-varying discrete dynamic system and synthesized by using the feedback control based on the volume balance at each signalized intersection. The signal control algorithm in which the three signal control parameters are searched systematically so as to minimize the sum of congestion lengths along the arterials is presented. From the comparison of congestion lengths between measurement values controlled by a pattern selection method and simulation values, it is confirmed that the signal control system and the signal control algorithm work effectively along the route 2 in Hiroshima city, Japan.