Degree

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

Document Type

Dissertation

Abstract

Connected and automated truck platooning (CAT) offers significant potential for improving road transportation efficiency, sustainability, and safety. While past studies typically isolated impacts on fuel consumption, safety, or pavement performance, this research comprehensively examines truck platooning configurations, including platoon size, headway distances, lane use, and market penetration, considering interactions with human-driven vehicles.

This dissertation achieves five main objectives: (1) assessing truck platoon configurations' impact on fuel consumption; (2) exploring traffic operation and safety impacts, including drivers' merging/diverging behaviors; (3) analyzing lane-change strategies' effects on safety and operational efficiency; (4) evaluating overall highway safety and efficiency impacts; and (5) investigating impacts on pavement across climatic zones.

Field experiments demonstrated that negative binomial regression models most accurately (74%) predict fuel savings, revealing increased platoon size and decreased spacing can yield fuel savings up to 16%. Driving simulator experiments involving 85 participants indicated increasing headway distances to 60 feet improved merging efficiency, reducing Time-to-Merge (TTM) by 44.6% to 4.1 seconds. Additionally, the First Vehicle Changes Lane First (FVCLF) strategy enhanced traffic safety and efficiency, increasing average Time-to-Collision (TTC) to 3.145 seconds and reducing delay by approximately 28.8% compared to Last Vehicle Changes Lane First (LVCLF).

Microsimulation analysis combined with Structural Equation Modeling (SEM) across 257 scenarios further confirmed FVCLF’s superior performance, reducing vehicle delay by 4.62 seconds and Time-to-Diverge (TTD) by 2.92 seconds per vehicle. Pavement analysis using mechanistic-empirical modeling found shorter truck spacing significantly increased pavement damage, particularly rutting by 18.2% and fatigue cracking by up to 376%. Damage intensified in dry-freeze climates; for example, rutting increased from 9 mm to 15 mm when increasing platoon size from two to five trucks, and AC layer rutting doubled. Increasing spacing from 6.5 to 30 feet notably reduced rutting by nearly 20%.

These findings emphasize the critical need for balanced platoon configurations, recommending specific strategies for policymakers and planners aiming to optimize benefits while minimizing negative pavement and safety impacts, thus enhancing road transportation sustainability and efficiency.

Date

7-17-2025

Committee Chair

Hassan, Hany

DOI

10.31390/gradschool_dissertations.6893

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Available for download on Monday, July 17, 2028

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