Highway Capacity Manual 2000 CHAPTER 25
RAMPS AND RAMP JUNCTIONS
CONTENTS
INTRODUCTION ……………………………………………………………………………………….. 25-1 Scope of the Methodology ……………………………………………………………………. 25-1 Limitations of the Methodology………………………………………………………………. 25-1 II. METHODOLOGY ………………………………………………………………………………………. 25-1 Ramp Roadways …………………………………………………………………………………. 25-3 LOS …………………………………………………………………………………………………… 25-4 MergeInfluence Areas …………………………………………………………………………. 25-5 Predicting Flow Entering Lanes 1 and 2 (v12) ……………………………………. 25-5 Determining Capacity …………………………………………………………………….. 25-7 Determining LOS…………………………………………………………………………… 25-8 Special Cases ………………………………………………………………………………. 25-8 Two-Lane On-Ramps ………………………………………………………………. 25-8 Lane Additions ……………………………………………………………………….. 25-9 Major MergeAreas………………………………………………………………….. 25-9 On-Ramps on Ten-Lane Freeway (Five Lanes in Each Direction) ………………………………………………………………… 25-10 Left-Hand On-Ramps …………………………………………………………….. 25-11 Effects of Ramp Control at On-Ramps …………………………………….. 25-11 Diverge Influence Areas……………………………………………………………………… 25-11 Predicting Flow Entering Lanes 1 and 2 (v12) ………………………………….. 25-12 Determining Capacity …………………………………………………………………… 25-14 Determining LOS …………………………………………………………………………. 25-14 SpecialCases …………………………………………………………………………….. 25-15 Two-Lane Off-Ramps …………………………………………………………….. 25-15 Lane Drops ………………………………………………………………………….. 25-16 Major Diverge Areas ………………………………………………………………25-16 Off-Ramps on Ten-Lane Freeways (Five Lanes in One Direction) ………………………………………………………………….. 25-17 Left-Hand Off-Ramps …………………………………………………………….. 25-17 Overlapping Ramp Influence Areas ……………………………………………………… 25-17 Determining Speed at Ramp Influence Areas………………………………………… 25-18 III. APPLICATIONS ………………………………………………………………………………………. 25-19 Computational Steps ………………………………………………………………………….. 25-20 Planning Applications…………………………………………………………………………. 25-20 Analysis Tools …………………………………………………………………………………… 25-22 IV. EXAMPLE PROBLEMS …………………………………………………………………………….. 25-23 Example Problem 1 ……………………………………………………………………………. 25-24 Example Problem 2 (Part I)…
