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Fuzzy Dynamic Traffic Assignment Model. Transportation Program, CEE Xuegang Ban Dec. 14, 2001. Introduction to Traffic Assignment. Assign Traffic Flow to Links of The Network Given OD Assumption: Each Driver Tries to Minimize His Perceived Travel Time Characteristics:
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Fuzzy Dynamic Traffic Assignment Model Transportation Program, CEE Xuegang Ban Dec. 14, 2001
Introduction to Traffic Assignment • Assign Traffic Flow to Links of The Network Given OD • Assumption: Each Driver Tries to Minimize His PerceivedTravel Time • Characteristics: - Stochastic and Dynamic - Fuzziness of Driver’s Perception Over Travel Time
Fuzzy Sets of Perceived Link Travel Time • Deterministic Link Travel Time • Actual Link Travel Time • Fuzzy Sets of Perceived Link Travel Time • NORMAL • CONGESTED • INCIDENT • CONSTRUCTION • SPECIAL EVENTS Membership Functions for Fuzzy Sets of Perceived Link Travel Time
Fuzzy Sets of Perceived Path Travel Time • Fuzzy Number Addition Problem • Dubois and Prade’s method - Flattening, Decomposition, Operation * and Union Fuzzy Addition Illustration
Fuzzy Assignment • Use Fuzzy Shortest Path Algorithm to Find S (Blue and Bush’s Method) S: Set of Shortest Paths • Membership: • : Traffic Flow from Origin O to Destination D • : Traffic Flow in Path
Results • Test Network: • Link Properties:
Results (Cont.) — Scenario #1 • All Links Are NORMAL • Both SDTA/FDTA Can Solve • This Problem • Difference Is Less Than 4%
Results (Cont.) – Scenario #2 • Link 1 and 6 Are CONGESTED • All Other Links Are NORMAL • FDTA Can Solve This Problem • SDTA Cannot. • Most of Drivers(70%) Will Choose • 1->4->5->6->2(Link 2, 4, 5, 7)