Traffic light circuit diagrams can be viewed at the ElecCircuit, Sigmatone and 555-Timer-Circuit websites. The latter of these sources provides a simplified circuit diagram for otherwise complex traffic lights at a 4-way intersection. ElecCircuit provides diagrams for two types of traffic light circuits.
As well as displaying diagrams, the ElecCircuit website guides users through the process of constructing their own traffic light circuits, including detailed explanations of all components and their functions.
The Sigmatone website has a single simple traffic light controller circuit diagram to view online, along with a list of required components and a brief explanation of the circuit.