12 hcm2000 HIGHWAY CONCEPTS.pdf

Highway Capacity Manual 2000 12-i Chapter 12 - Highway Concepts CHAPTER 12 HIGHWAY CONCEPTS CONTENTS I. INTRODUCTION 12-1 II. MULTILANE HIGHWAYS 12-1 Multilane Highway Capacity 12-2 Free-Flow Speed 12-2 Relationships Between Highway Types 12-3 Speed-Flow and Density-Flow Relationships 12-3 Factors Affecting FFS 12-3 Lane Width and Lateral Clearance 12-4 Median Type 12-5 Access Points 12-6 Other Factors 12-6 Factors Affecting Flow Rate 12-7 Heavy Vehicles 12-7 Driver Population 12-7 LOS 12-7 Required Input Data and Estimated Values 12-8 Lane Width and Lateral Clearance 12-8 Median 12-9 Access-Point Density 12-9 Specific Grade or General Terrain 12-9 Base FFS 12-10 Length of Analysis Period 12-10 PHF 12-10 Percentage of Heavy Vehicles 12-10 Driver Population Factor 12-10 Service Volume Table 12-10 III. TWO-LANE HIGHWAYS 12-11 Classification of Two-Lane Highways 12-12 Base Conditions 12-13 Basic Relationships 12-13 Passing Lanes on Two-Lane Highways 12-15 LOS 12-15 Required Input Data and Estimated Values 12-17 Highway Classes 12-17 Lane Width and Shoulder Width 12-17 Access-Point Density 12-17 Specific Grade or General Terrain 12-17 Percentage of No-Passing Zones 12-17 Base FFS 12-18 Length of Passing Lane 12-18 Length of Analysis Period 12-18 PHF 12-18 Directional Split 12-18 Percentage of Heavy Vehicles 12-19 Service Volume Table 12-19 IV. REFERENCES 12-19 Highway Capacity Manual 2000 Chapter 12 - Highway Concepts 12-ii EXHIBITS Exhibit 12-1. Speed-Flow Relationships on Multilane Highways 12-4 Exhibit 12-2. Density-Flow Relationships on Multilane Highways 12-4 Exhibit 12-3. Required Input Data for Multilane Highways 12-9 Exhibit 12-4. Default Access-Point Density 12-9 Exhibit 12-5. Example Service Volumes for Multilane Highways 12-11 Exhibit 12-6. Speed-Flow and Percent Time-Spent-Following Flow Relationships for Two-Way Segments with Base Conditions 12-14 Exhibit 12-7. Speed-Flow and Percent Time-Spent-Following Flow Relatio