Actuated signals: 
In this type of signal system, signal timings are completely influenced by the traffic volume as detected on all approach roads (whereas it is not influenced as per the time of the day).Initial cost is very high for the installation of traffic signals. Sensors and detectors are used to operate the signals. 
Semi actuated signals: 
In this type of signal system, timings are affected when vehicles are detected. Suitable only when low volume road intersects with high volume road. 

Fixed time signals: 

The timing of each phase of the cycle is fixed based on the traffic studies. Signals time cycle does not change with respect to the change in traffic flow at the intersection.