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Updated: May 9, 2026

Trajectory Data Analyses for Pedestrian Space-time Activity Study
Published on: February 25, 2013
Vehicle and Pedestrian Traffic Signal Performance Measures Using LiDAR-Derived Trajectory Data
Enrique D Saldivar-Carranza1, Jairaj Desai1, Andrew Thompson1
1Joint Transportation Research Program, Lyles School of Civil and Construction Engineering, Purdue University, West Lafayette, IN 47907, USA.
LiDAR sensors precisely track vehicles and pedestrians at intersections, enabling real-time traffic signal performance analysis. This technology offers new insights into pedestrian movement, potentially improving traffic signal timing.
Area of Science:
- Transportation Engineering
- Traffic Flow Analysis
- Sensor Technology
Background:
- Signalized intersections are critical nodes in transportation networks.
- Traditional traffic data collection methods have limitations in accuracy and scope.
- Light Detection and Ranging (LiDAR) offers high-resolution object tracking capabilities.
Purpose of the Study:
- To develop and validate methodologies for estimating traffic signal performance measures using LiDAR data.
- To analyze vehicle and pedestrian movement patterns at signalized intersections.
- To assess the potential of LiDAR for real-time traffic monitoring and pedestrian behavior analysis.
Main Methods:
- Utilized LiDAR trajectory data from an intersection over a 24-hour period, capturing millions of vehicle and pedestrian waypoints.
- Generated Purdue Probe Diagrams (PPDs) from linear-referenced trajectories for both vehicles and pedestrians.
- Applied vehicle-based PPDs to estimate performance measures like queue lengths, arrivals on green, and level of service; pedestrian-based PPDs for wait times and multi-crosswalk traversal.
Main Results:
- Successfully estimated key traffic signal performance measures (e.g., 85th percentile queue lengths, Highway Capacity Manual Level of Service) from LiDAR data.
- Quantified pedestrian movement, including wait times and the proportion of individuals crossing multiple paths.
- Determined pedestrian walking speeds (e.g., 15th percentile at 3.9 ft/s), enabling data-driven adjustments to signal timing.
Conclusions:
- LiDAR technology provides a robust method for detailed, real-time assessment of traffic signal performance for both vehicles and pedestrians.
- The ability to measure pedestrian speeds directly allows for more informed and potentially safer traffic signal timing strategies compared to standard guidelines.
- LiDAR data enhances traffic management capabilities by offering granular insights into intersection dynamics.
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