Enhancing Road Safety Through Multi-Camera Image Segmentation with Post-Encroachment Time Analysis

TL;DR

This paper introduces a real-time, multi-camera vision system using advanced segmentation and PET analysis for detailed, scalable intersection safety assessment, demonstrating high accuracy and efficiency on edge devices.

Contribution

It presents a novel multi-camera framework with pixel-level PET computation and dynamic hazard visualization, enabling real-time, high-resolution safety analysis at intersections.

Findings

Achieved sub-second hazard detection accuracy.

Processed data at an average of 2.68 FPS on edge devices.

Validated the system's effectiveness in real-world intersection safety monitoring.

Abstract

Traffic safety analysis at signalized intersections is vital for reducing vehicle and pedestrian collisions, yet traditional crash-based studies are limited by data sparsity and latency. This paper presents a novel multi-camera computer vision framework for real-time safety assessment through Post-Encroachment Time (PET) computation, demonstrated at the intersection of H Street and Broadway in Chula Vista, California. Four synchronized cameras provide continuous visual coverage, with each frame processed on NVIDIA Jetson AGX Xavier devices using YOLOv11 segmentation for vehicle detection. Detected vehicle polygons are transformed into a unified bird's-eye map using homography matrices, enabling alignment across overlapping camera views. A novel pixel-level PET algorithm measures vehicle position without reliance on fixed cells, allowing fine-grained hazard visualization via dynamic heatmaps, accurate to 3.3 sq-cm. Timestamped vehicle and PET data is stored in an SQL database for long-term monitoring. Results over various time intervals demonstrate the framework's ability to identify high-risk regions with sub-second precision and real-time throughput on edge devices, producing data for an 800 x 800 pixel logarithmic heatmap at an average of 2.68 FPS. This study validates the feasibility of decentralized vision-based PET analysis for intelligent transportation systems, offering a replicable methodology for high-resolution, real-time, and scalable intersection safety evaluation.