Consideration was given to a well-known problem of traffic control at an individual intersection with minimal total delay. The constraints on control (duration of green light in the main direction) and phase variables (queue lengths along each direction) were taken into account. A continuous traffic model and the methods of the optimal control theory were used. An analytical solution was established in the form of feedback control design. The solutions obtained were compared with the results acquired in the 1960s and 1970s.