Automated Pedestrian Crosswalk Warning System
Sensor-based safety prototype that detects pedestrians and cyclists approaching or entering a crosswalk, activating yellow or red warning lights to alert drivers in low-visibility areas and improve intersection safety.
Pedestrian safety is a persistent challenge at intersections without traffic signals, where drivers can miss people crossing—especially in low-light or poor-visibility conditions. This project focused on building a simple, low-cost warning system that increases driver awareness using clear visual cues when pedestrians approach or enter a crosswalk.
The core idea was straightforward: use sensors to detect movement near the crossing zone, then activate highly-visible warning lights to prompt earlier driver reactions and reduce close calls. The result was a functional prototype designed to be affordable, understandable, and feasible to implement at scale.
The prototype used a two-state warning concept. A yellow light activates when someone approaches the crosswalk, and a red light activates once a person is actively crossing. This distinction helps drivers anticipate pedestrian movement rather than reacting at the last moment.
Pedestrian detection was built using a layered sensing approach. An ultrasonic sensor detected pedestrians approaching the crosswalk, while a passive infrared (PIR) sensor confirmed when a pedestrian entered the crossing zone. Timers and logic thresholds were used to reduce false activations and keep signals active for the duration of a crossing.
A working prototype was constructed using off-the-shelf components with an emphasis on affordability and practical build constraints. The total prototype cost came out to approximately $105, demonstrating that meaningful safety improvements can be achieved without expensive infrastructure changes.
Building the system required balancing reliability, simplicity, and usability—keeping the logic easy to understand while still robust enough to handle real-world movement and timing.
The system was tested in real-world conditions across multiple pedestrian movement types, including walking, running, biking, and skateboarding. Results showed approximately 80–90% detection accuracy, validating the sensing approach while highlighting opportunities for improvement through higher-grade sensors and better placement.
While the prototype was not intended for permanent deployment, the project emphasized realistic engineering tradeoffs—system reliability, human interpretation of signals, and potential liability concerns. Future improvements would focus on sensor redundancy, weatherproofing, and integration into existing urban infrastructure.
Key takeaway
This project demonstrated the full engineering lifecycle—from problem identification and requirements definition to prototyping, testing, and critical evaluation—while emphasizing practical, low-cost solutions to real-world safety challenges.