Density-Based Smart Traffic Signal Controller with Monitoring Dashboard

Fixed-time traffic signals waste green time on empty approaches while vehicles queue on the busy ones — every commuter knows the feeling. The fix is density-responsive control: measure the actual vehicle count per approach and allocate green time where the queue is. This project demonstrates it on a 4-way junction model: IR sensor pairs count vehicles entering each approach, an Arduino Mega runs the adaptive timing state machine with minimum/maximum green bounds and amber clearance, and LED signal heads show the live phases. A dashboard mirrors the junction schematically with live signal states, per-approach vehicle counts, the current phase timer and a log of timing decisions. Pedestrian demand is handled with a crossing button. The project keeps claims honest: it demonstrates the control logic and the sensing method at model scale, with the report discussing what a real deployment would add — loops or cameras, conflict monitoring and fail-safe design.

1. IR sensor pairs on each approach detect passing model vehicles; firmware debounces and increments the per-approach count.
2. At each phase decision point, the controller compares approach densities and computes green times within the configured min/max bounds.
3. The Arduino Mega drives the 4-way LED signal heads through the green-amber-all-red sequence with the computed timings.
4. Counts, phase state and timing decisions are sent to the dashboard, which renders the live junction schematic and the decision log.
5. A pedestrian button press queues a crossing phase, serviced at the next safe point in the cycle.
6. The emergency override input, when active, holds the priority approach green and logs the preemption event.
7. Scripted scenarios in the manual let the demonstrator show fixed-time vs adaptive behaviour side by side.

Tech stack:

• Arduino Mega 2560
• IR sensor modules x8 (approach pairs)
• 4-way LED signal head model
• Pedestrian crossing button + indicators
• ESP8266/ESP32 telemetry link (dashboard)
• Web dashboard (junction schematic)
• 4-way junction demonstration model
• Emergency override switch (demo)

• [Per-approach vehicle counting] IR sensor pairs on all four approaches count vehicles in, giving the density input the controller decides on.
• [Adaptive green timing] Green time per phase adapts between configured minimum and maximum bounds based on measured approach density — busy approaches earn more green.
• [Full phase state machine] Green, amber and all-red clearance phases with pedestrian servicing follow a proper signal-timing structure, not just blinking lights.
• [Live junction dashboard] A schematic junction view with live signal heads, per-approach counts, phase timer and the timing-decision log.
• [Pedestrian handling] A crossing button inserts a pedestrian phase; the dashboard logs pedestrian services.
• [Emergency override input] A documented priority input holds green for the emergency approach — demonstrated with a switch, discussed for real sirens/RF.
• [Scenario demonstration] The manual includes scripted traffic scenarios (rush on north, balanced, night-low) to show the adaptation clearly in the viva.

• Working 4-way junction model (signal heads, IR sensors, pedestrian crossing, controller)
• Complete firmware source (counting, adaptive timing state machine, pedestrian, preemption)
• Live web dashboard (junction schematic, counts, decision log) demonstrated with the model
• Circuit and wiring documentation
• Scripted demonstration scenarios (rush, balanced, night) with expected outcomes
• Component list with ratings
• Project report PDF (signal timing background, adaptive control, sensor methods, methodology)
• PPT presentation for final review
• Viva Q&A preparation document (signal phases, density control, IR sensing, fail-safety)
• Setup and demonstration guide

• Demonstrated at model scale with IR counting — real junctions use inductive loops, radar or cameras, discussed as deployment notes in the report.
• IR pairs count objects breaking the beam; tailgating vehicles can under-count, which the manual notes.
• The emergency override is a demonstrated input, not a certified preemption system with conflict monitoring.
• Timing bounds are model-scale seconds; real junction timings follow IRC/traffic engineering standards, referenced in the report.
• Fail-safe behaviour (e.g. flashing amber on sensor fault) is implemented at demo level; certified conflict monitors are out of scope.