12.1.6 Overview

Roundabout analysis begins with determining whether a roundabout is an appropriate intersection control method for a particular location. See Chapter 10
for guidance on undertaking the ICE process. The prescribed methods in this chapter focuses on roundabout analysis for motorized vehicles, pedestrians, and bicycles. Various methods of analysis are available for the two stages of project development and are discussed in this chapter. See Table 12-1

for the selection of an appropriate analysis tool according to the project planning and schematic development phases of the project development process

Table 12-1: Project Development and Analysis Methodology
Stage of Project Development Process	Application	Input Data Needed	Potential Operational Analysis Tool
Intersection Control Evaluation (ICE) Stage 1	Sizing of roundabouts – single lane versus multilane	Peak hour traffic volumes	CAP-X, Appendix M
Intersection Control Evaluation (ICE) Stage 2 and Subsequent Geometric Design Refinement	Conceptual design of roundabouts with configurations within the scope of the HCM	Peak hour traffic volumes, lane configuration (multilane) from Appendix M	HCM 6 Capacity Methodology (HCS, Synchro) and other deterministic software models, e.g., Junctions , Sidra
	Conceptual analysis of bicyclist and pedestrian quality of service	Vehicular traffic, bicycle and pedestrian volumes, crosswalk design and traffic control	Techniques in NCHRP 1043 Chapter 9.8
	System analysis with two or more closely spaced intersections	Traffic volumes, lane configuration, intersection spacing and geometry	Simulation (Synchro SimTraffic, Vissim, etc.)

12.1 Introduction