Advanced Traffic Light Control System with Emergency Preemption
Technologies: Rockwell Studio 5000 Logix Designer · ControlLogix 5570 Emulator
Key Concepts: State Machine Design · Time-of-Day Scheduling · Emergency Vehicle Preemption · Pedestrian Safety · Conflict Detection
Overview
A comprehensive traffic intersection control system implementing intelligent signal timing, emergency vehicle preemption, pedestrian crosswalk management, and safety conflict detection — built and validated entirely in Studio 5000 with the ControlLogix 5570 Emulator.
This project demonstrates professional traffic control system design with real-world features including adaptive timing based on time-of-day, emergency vehicle priority routing, pedestrian walk signals with countdown timers, and critical safety interlocks.
Project Highlights
- Multi-Mode Operation — Auto/Manual/Night modes with seamless transitions and safe sequencing
- Time-of-Day Scheduling — Normal, Rush Hour (NS), Rush Hour (EW), and Night Mode with adaptive green times
- Emergency Vehicle Preemption — North-South and East-West emergency detection with immediate priority clearance
- Pedestrian Safety System — Walk/Don’t Walk signals with flashing countdown and timing coordination
- Conflict Detection — Real-time monitoring prevents simultaneous green signals with automatic safety beacon activation
- Modular State Machine — Clean 6-state cycle: NS Green → NS Yellow → All Red → EW Green → EW Yellow → All Red
- HMI Development — Complete FactoryTalk View ME interface with real-time visualization and operator controls
- Comprehensive Documentation — Fully commented ladder logic with clear routine organization
🖥️ HMI Screenshots
Main Visualization Screen
Features:
- Four-way intersection layout with real-time traffic light visualization
- Pedestrian walk/don’t walk indicators (NS and EW)
- Interactive pedestrian request buttons
- System shutdown control
- Tab navigation for Status and Manual Mode
System Status Dashboard
Real-Time Monitoring:
- Current State display (States 1-8 with descriptions)
- Time-of-Day Mode indicator (Night, Normal, Rush Hour NS, Rush Hour EW)
- Emergency Status indicator (Active/Not Active)
- Clean, at-a-glance system overview
Manual Mode Controls
Operator Control Panel:
- Manual Mode enable/disable toggle
- Independent NS Green override
- Independent EW Green override
- All Red override for maintenance
- Direct operator control with safety interlocks maintained
Intersection States
State 1: NS Green Active
- North-South direction: Green light active
- East-West direction: Red lights active
- Pedestrian signals coordinated with traffic flow
All Red Clearance
- All directions showing red
- 2-second intersection clearance
- Safety buffer between opposing flows
Project Documentation
1. Project Summary
Contents:
- System objectives and scope
- Operating mode descriptions
- State machine architecture
- Safety system overview
- Testing methodology
2. Complete Ladder Logic
Contents:
- All 9 routine implementations
- State machine logic (R05_Process_Logic)
- Emergency preemption (R04_Emergency_Mode)
- Pedestrian control (R07_Pedestrian_Handling)
- Output arbitration (R08_Lights_MappingOutputs)
- Time-of-day scheduling (R02_ToD_State)
Testing & Validation
Complete test coverage achieved:
- ✅ 13 functional tests (state machine, emergency preemption, pedestrian control)
- ✅ 6 safety tests (conflict detection, clearance intervals, emergency override)
- ✅ 4 time-of-day mode tests (normal, rush hour NS/EW, night mode)
All testing performed using ControlLogix 5570 Emulator in Studio 5000 v33 with no physical hardware required.
Learning Outcomes
This project demonstrates proficiency in:
- State Machine Design - Timer-based sequencing with priority arbitration
- Traffic Control Systems - Signal phasing, emergency preemption, pedestrian safety
- Safety-Critical Logic - Conflict detection, clearance intervals, interlocking
- Modular Architecture - 9 organized routines with comprehensive documentation