Collaborative Variable Speed Limit and Ramp Metering for Crash Risk

The expressway is divided into multiple segments with different control strategies applied to each segment based on real-time crash risk assessment. The system segments the control approach by identifying high-risk segments and applying targeted variable speed limits and ramp metering to those specific segments rather than uniform single-point control, thereby improving traffic safety without excessive complexity increase

The control strategy transitions from single-point (one location) to multi-point (multiple locations along the expressway) control. By adding the spatial dimension of multiple control points and coordinating them together, the system prevents crash risk shifting and improves overall traffic safety while maintaining manageable complexity through systematic coordination

Variable speed limits and ramp metering controls are applied locally only to segments identified as having high crash risk, rather than extensively across the entire expressway. The system assesses crash risk for each segment and applies controls selectively to high-risk areas, thereby maintaining effective crash prevention while minimizing control duration and implementation distance to preserve traffic efficiency

The system applies control actions partially and selectively only where needed (high-risk segments) rather than uniformly across all segments. This partial action approach ensures adequate crash prevention capability is achieved in critical areas while avoiding unnecessary extensive control that would reduce overall traffic efficiency and increase implementation distance