A railway station has four platforms marked as P1, P2, P3 and P4 as shown in the figure 5.2. The trains can come only from left hand side and enter these platforms. The trains are to be routed to these platforms in the order of preference P1, P2, P3 and in the last to P4. Each platform has a switch will be turned ON if the platform is not empty. There is an outer signal S which will be either green or red. This signal will be green if it allows the train to enter the station otherwise red. There are three track changer switches T1, T2, T3 which allows changing the tracks. Design a railway track switching circuit using AND, OR and NOT gates, which can perform the operations mentioned above
