Civil and Environmental Engineering

Permanent URI for this collectionhttps://uwspace.uwaterloo.ca/handle/10012/9906

This is the collection for the University of Waterloo's Department of Civil and Environmental Engineering.

Research outputs are organized by type (eg. Master Thesis, Article, Conference Paper).

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Browsing Civil and Environmental Engineering by Author "Bachmann, Christian"

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    Automatically Assessing the Need for Traffic Signal Retiming Using Connected Vehicle Data
    (University of Waterloo, 2023-11-27) Ghaleh, Pirooz; Bachmann, Christian; Fu, Liping
    Traffic signal controllers are a critical element in managing urban traffic systems effectively. The emergence of Automated Traffic Signal Performance Measures (ATSPM), aided by recent technological advancements, allows for continuous traffic performance monitoring, and supports traffic agencies in taking proactive measures. High-resolution trajectory data from connected vehicles (CVs) has surfaced as a cost-effective method for assessing ATSPM. Although various metrics have been developed to measure traffic signal performance, none have been specifically designed to predict the benefits of signal retiming. This study devises a novel metric using CV data to estimate the potential reduction in overall intersection delay that could result from signal retiming. Hence, this measure uniquely estimates the potential avoidable delay rather than simply the observed signal performance. This new metric could enable traffic agencies to predict the benefits of potential signal retiming without the need for conducting costly traffic surveys. Such a tool would help these agencies prioritize locations and times of day for signal retiming. This study outlines the process of calculating this index and employs the VISSIM microsimulation software to demonstrate and evaluate the index under various traffic scenarios and CV market penetration rates. In our experiments, the suggested metric successfully detected signal retiming needs in situations involving an imbalanced degree of saturation, traffic demand fluctuations on competing movements, and changes in traffic direction, even with CV penetration rates as low as 10%.
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    LiDAR-Driven Calibration of Microscopic Traffic Simulation for Balancing Operational Efficiency and Prediction of Traffic Conflicts
    (University of Waterloo, 2025-01-21) Farag, Natalie; Bachmann, Christian; Fu, Liping
    Microscopic traffic simulation is a proactive tool for road safety assessment, offering an alternative to traditional crash data analysis. Microsimulation models, such as PTV VISSIM, replicate traffic scenarios and conflicts under various conditions, thereby aiding in the assessment of driving behavior and traffic management strategies. When integrated with tools like the Surrogate Safety Assessment Model (SSAM), these models estimate potential conflicts. Research often focuses on calibrating these models based on traffic operation metrics, such as speed and travel time, while neglecting safety performance parameters. This thesis investigates the effects of calibrating microsimulation models for both operational metrics including travel time and speed, and safety metrics including traffic conflicts and Post Encroachment Time (PET) distribution, using LiDAR sensor data. The calibration process involves three phases: performance calibration, performance and safety calibration, and only safety calibration. The results show that incorporating safety-focused parameters enhances the model's ability to replicate observed conflict patterns. The study highlights the trade-offs between operational efficiency and safety, with adjustments to parameters like standstill distance improving safety outcomes without significantly compromising operational metrics. Furthermore, there is a substantial difference in the calibrated minimum distance headway for the safety model, highlighting the trade-off between operational efficiency and safety. While the operational calibration focuses on optimizing flow, the safety calibration prioritizes realistic conflict simulation, even at the cost of reduced flow efficiency. The research emphasizes the importance of accurately simulating real-world driver behavior through adjustments to parameters like the probability and duration of temporary lack of attention.