As traffic congestion during rush hours is a growing problem for most cities, there is an increasing need for more effective management of traffic signal control and traffic assignment systems. We present here a new adaptive system based on a linear programming model for the signal-control problem. The objective is to minimize the total length of the queues of vehicles waiting at each intersection. The model is based on traffic information provided by real-time sensors installed at each intersection. In order to compare the performance of our program with the current scheduling designed by the transit office of Buenos Aires city, we used a traffic simulation system and real traffic flow data of two pilot areas of the city. Preliminary results are very promising.