5_Way Junction

This project simulates a real five-way road junction where five separate roads meet at a single intersection. Each road has its own set of three traffic lights , red, amber, and green, giving a total of fifteen LEDs across the whole circuit. The lights follow the authentic UK traffic light sequence, cycling through each road one at a time so that while one road receives a green signal, all four remaining roads stay on red. Once a road has completed its full sequence it returns to red, a short safety pause occurs, and then the next road begins its cycle. This continues in a continuous loop for as long as the Arduino is powered.

What makes this project particularly interesting from an electronics perspective is that all fifteen LEDs are controlled using only three Arduino output pins. Normally, driving fifteen LEDs independently would require fifteen separate pins, which would exhaust the Arduino's available outputs. Instead, this project introduces two 74HC595 shift register chips wired in a daisy-chain configuration. The Arduino sends data to the first chip, and any overflow automatically passes into the second chip, effectively creating a sixteen-output controller from a single three-wire connection. This technique,  known as serial-to-parallel conversion, is widely used in real-world electronics including LED signage, industrial control panels, and consumer devices.