................................ ................................ ................................ ................................ ... ix CHAPTER 1 . INTRODUCTION ................................ ................................ ................................ ... 1 1.1. Current Tendencies in Passenger and Freight Transport ................................ ..................... 1 1.1.1. Road transport ................................ ................................ ................................ ............... 5 1.1.2. Rail transport ................................ ................................ ................................ ................. 7 1.1.3. Water transport ................................ ................................ ................................ .............. 8 1.1.4. Air transport ................................ ................................ ................................ .................. 9 1.2. Public Transit and Bus Transportation ................................ ................................ .............. 11 1.3. Focus of This Study ................................ ................................ ................................ ........... 15 CHAPTER 2 . LITERATURE REVIEW ................................ ................................ ...................... 17 2.1. Environmental Sustainability Concerns ................................ ................................ ............. 17 2.2. New Generation Vehicles ................................ ................................ ................................ .. 22 2.3. Modeling of Alternative Fuels ................................ ................................ ........................... 29 2.4. Addressing Service Quality Issues ................................ ................................ ..................... 30 2.5. Others ................................ ................................ ................................ ................................ . 36 2.6. Literature Summary and Contributions of the Prese nt Study ................................ ............ 45 CHAPTER 3 . MODEL DESCRIPTION ................................ ................................ ...................... 46 3.1. Simulation ................................ ................................ ................................ .......................... 46 3.2. Advantages and Disadvantages of Simulation ................................ ................................ ... 47 3.3. FlexSim Simulation Environment ................................ ................................ ...................... 48 3.4. Modelling in FlexSim ................................ ................................ ................................ ........ 49 vi 3.4.1 . Procedure for Modelling ................................ ................................ ............................. 57 3.4.2 . Performance Indicators ................................ ................................ ............................... 62 CHAPTER 4 . NUMERICAL EXPERIMENTS ................................ ................................ ........... 63 CHAPTER 5 . CONCLUSIONS AND FUTURE RESEARCH ................................ ................... 73