AASHTO Green book 7e

Cover Page
EXECUTIVE COMMITTEE 2018–2019
TECHNICAL COMMITTEE ON GEOMETRIC DESIGN 2018–2019
COMMITTEE ON DESIGN 2017–2018
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
PREFACE
CHAPTER 1 New Framework for Geometric Design
	1.1 INTRODUCTION
	1.2 PROJECT PURPOSE AND NEED
	1.3 OVERVIEW OF THE NEW FRAMEWORK FOR GEOMETRIC DESIGN
	1.4 FUNCTIONAL CLASSIFICATION FOR MOTOR VEHICLES
		1.4.1 Hierarchy of Motor Vehicle Movement
		1.4.2 Access Control and Mobility Needs
		1.4.3 Functional System Characteristics
			1.4.3.1 Definitions Of Urban And Rural Areas
			1.4.3.2 Functional Categories
			1.4.3.3 Functional Systems for Rural Areas
				1.4.3.3.1 Rural Principal Arterial System
				1.4.3.3.2 Rural Minor Arterial System
				1.4.3.3.3 Rural Collector System
				1.4.3.3.4 Rural Local Road System
			1.4.3.4 Functional Systems for Urban Areas
				1.4.3.4.1 Urban Principal Arterial System
				1.4.3.4.2 Urban Minor Arterial Street System
				1.4.3.4.3 Urban Collector Street System
				1.4.3.4.4 Urban Local Street System
		1.4.4 Functional Classification as a Design Type
	1.5 CONTEXT CLASSIFICATION FOR GEOMETRIC DESIGN
		1.5.1 Context Classes for Roads and Streets in Rural Areas
			1.5.1.1 Rural Context
			1.5.1.2 Rural Town Context
		1.5.2 Context Classes for Roads and Streets in Urban Areas
			1.5.2.1 Suburban Context
			1.5.2.2 Urban Context
			1.5.2.3 Urban Core Context
		1.5.3 Design Guidance for Specific Context Classes
	1.6 MULTIMODAL CONSIDERATIONS
		1.6.1 Road and Street User Groups/Transportation Modes
			1.6.1.1 Automobiles
			1.6.1.2 Bicyclists
			1.6.1.3 Pedestrians
			1.6.1.4 Transit
			1.6.1.5 Trucks
		1.6.2 Consideration of All Transportation Modes in Design
	1.7 DESIGN PROCESS TO ADDRESS SPECIFIC PROJECT TYPES
		1.7.1 New Construction Projects
		1.7.2 Reconstruction Projects
		1.7.3 Construction Projects on Existing Roads
	1.8 DESIGN FLEXIBILITY
	1.9 PERFORMANCE-BASED DESIGN
	1.10 REFERENCES
CHAPTER 2 Design Controls and Criteria
	2.1 INTRODUCTION
	2.2 DRIVER PERFORMANCE AND HUMAN FACTORS
		2.2.1 Introduction
		2.2.2 Older Drivers and Older Pedestrians
		2.2.3 The Driving Task
		2.2.4 The Guidance Task
			2.2.4.1 Lane Placement and Road Following
			2.2.4.2 Car Following
			2.2.4.3 Passing Maneuvers
			2.2.4.4 Other Guidance Activities
		2.2.5 The Information System
			2.2.5.1 Traffic Control Devices
			2.2.5.2 The Roadway and Its Environment
		2.2.6 Information Handling
			2.2.6.1 Reaction Time
			2.2.6.2 Primacy
			2.2.6.3 Expectancy
		2.2.7 Driver Error
			2.2.7.1 Errors Due to Driver Deficiencies
				2.2.7.1.1 Older Drivers
			2.2.7.2 Errors Due to Situation Demands
		2.2.8 Speed and Design
		2.2.9 Design Assessment
	2.3 TRAFFIC CHARACTERISTICS
		2.3.1 General Considerations
		2.3.2 Volume
			2.3.2.1 Average Daily Traffic
			2.3.2.2 Design Hour Traffic: Rural Areas
			2.3.2.3 Design Hour Traffic: Urban Areas
		2.3.3 Directional Distribution
		2.3.4 Composition of Traffic
		2.3.5 Projection of Future Traffic Demands
		2.3.6 Speed
			2.3.6.1 Operating Speed
			2.3.6.2 Running Speed
			2.3.6.3 Design Speed
		2.3.7 Traffic Flow Relationships
	2.4 HIGHWAY CAPACITY
		2.4.1 General Characteristics
		2.4.2 Application
		2.4.3 Capacity as a Design Control
			2.4.3.1 Design Service Flow Rate versus Design Volume
			2.4.3.2 Measures of Congestion
			2.4.3.3 Relation between Congestion and Traffic Flow Rate
			2.4.3.4 Acceptable Degrees of Congestion
		2.4.4 Factors Other Than Traffic Volume That Affect Operating Conditions
			2.4.4.1 Roadway Factors
			2.4.4.2 Alignment
			2.4.4.3 Weaving Sections
			2.4.4.4 Ramp Terminals
			2.4.4.5 Traffic Factors
			2.4.4.6 Peak Hour Factor
		2.4.5 Levels of Service
		2.4.6 Design Service Flow Rates
			2.4.6.1 Weaving Sections
			2.4.6.2 Multilane Highways without Access Control
			2.4.6.3 Arterial Streets and Highways in Urban Areas
			2.4.6.4 Intersections
	2.5 ACCESS CONTROL AND ACCESS MANAGEMENT
		2.5.1 General Conditions
		2.5.2 Basic Principles of Access Management
		2.5.3 Access Classifications
		2.5.4 Methods of Controlling Access
		2.5.5 Benefits of Controlling Access
	2.6 PEDESTRIANS
		2.6.1 General Considerations
		2.6.2 General Characteristics
		2.6.3 Walking Speeds
		2.6.4 Walkway Level of Service
		2.6.5 Intersections
		2.6.6 Reducing Pedestrian–Vehicular Conflicts
		2.6.7 Accommodating Persons with Disabilities
			2.6.7.1 Mobility Disabilities
			2.6.7.2 Vision Disabilities
			2.6.7.3 Cognitive Disabilities
			2.6.7.4 Hearing Disabilities
	2.7 BICYCLISTS
	2.8 DESIGN VEHICLES
		2.8.1 General Characteristics
		2.8.2 Minimum Turning Paths of Design Vehicles
		2.8.3 Vehicle Performance
		2.8.4 Vehicular Pollution
	2.9 SAFETY
		2.9.1 Key Factors Related to Traffic Crashes
			2.9.1.1 Roadway Design
			2.9.1.2 Roadside Design
			2.9.1.3 Traffic Control Devices
		2.9.2 Key Safety Resources
		2.9.3 Safety Improvement Programs
		2.9.4 Project Development Process
	2.10 ENVIRONMENT
	2.11 REFERENCES
CHAPTER 3 Elements of Design
	3.1 INTRODUCTION
	3.2 SIGHT DISTANCE
		3.2.1 General Considerations
		3.2.2 Stopping Sight Distance
			3.2.2.1 Brake Reaction Time
			3.2.2.2 Braking Distance
			3.2.2.3 Design Values
			3.2.2.4 Effect of Grade on Stopping
			3.2.2.5 Variation for Trucks
				3.2.2.5.1 New Construction vs. Projects on Existing Roads
		3.2.3 Decision Sight Distance
		3.2.4 Passing Sight Distance for Two-Lane Highways
			3.2.4.1 Criteria for Design
			3.2.4.2 Design Values
			3.2.4.3 Effect of Grade on Passing Sight Distance
			3.2.4.4 Frequency and Length of Passing Sections
		3.2.5 Sight Distance for Multilane Highways
		3.2.6 Criteria for Measuring Sight Distance
			3.2.6.1 Height of Driver’s Eye
			3.2.6.2 Height of Object
			3.2.6.3 Sight Obstructions
			3.2.6.4 Measuring Sight Distance
	3.3 HORIZONTAL ALIGNMENT
		3.3.1 Theoretical Considerations
		3.3.2 General Considerations
			3.3.2.1 Superelevation
			3.3.2.2 Side Friction Factor
			3.3.2.3 Distribution of e and f over a Range of Curves
		3.3.3 Design Considerations
			3.3.3.1 Normal Cross Slope
			3.3.3.2 Maximum Superelevation Rates for Streets and Highways
			3.3.3.3 Minimum Radius
			3.3.3.4 Effects of Grades
		3.3.4 Design for Highways in Rural Areas, and Freeways and High-Speed Streets in Urban Areas
			3.3.4.1 Side Friction Factors
			3.3.4.2 Superelevation
			3.3.4.3 Procedure for Development of Method 5 Superelevation Distribution
		3.3.5 Design Superelevation Tables
			3.3.5.1 Minimum Radius of Curve for Section with Normal Crown
		3.3.6 Design for Low-Speed Streets in Urban Areas
			3.3.6.1 Side Friction Factors
			3.3.6.2 Superelevation
		3.3.7 Turning Roadways
			3.3.7.1 Design Speed
			3.3.7.2 Maximum Superelevation for Turning Roadways
			3.3.7.3 Use of Compound Curves
		3.3.8 Transition Design Controls
			3.3.8.1 General Considerations
			3.3.8.2 Tangent-to-Curve Transition
				3.3.8.2.1 Minimum Length of Superelevation Runoff
				3.3.8.2.2 Minimum Length of Tangent Runout
				3.3.8.2.3 Location with Respect to End of Curve
				3.3.8.2.4 Limiting Superelevation Rates
			3.3.8.3 Spiral Curve Transitions
			3.3.8.4 Length of Spiral
				3.3.8.4.1 Length of Spiral
				3.3.8.4.2 Maximum Radius for Use of a Spiral
				3.3.8.4.3 Minimum Length of Spiral
				3.3.8.4.4 Maximum Length of Spiral
				3.3.8.4.5 Desirable Length of Spiral
				3.3.8.4.6 Length of Superelevation Runoff
				3.3.8.4.7 Limiting Superelevation Rates
				3.3.8.4.8 Length of Tangent Runout
				3.3.8.4.9 Location with Respect to End of Curve
			3.3.8.5 Compound Curve Transition
			3.3.8.6 Methods of Attaining Superelevation
			3.3.8.7 Design of Smooth Profiles for Traveled-Way Edges
			3.3.8.8 Axis of Rotation with a Median
				3.3.8.8.1 Case I
				3.3.8.8.2 Case II
				3.3.8.8.3 Case III
				3.3.8.8.4 Divided Highway
			3.3.8.9 Minimum Transition Grades and Drainage Considerations
			3.3.8.10 Transitions and Compound Curves for Turning Roadways
			3.3.8.11 Length of Spiral for Turning Roadways
			3.3.8.12 Compound Circular Curves
		3.3.9 Offtracking
			3.3.9.1 Derivation of Design Values for Widening on Horizontal Curves
		3.3.10 Traveled-Way Widening on Horizontal Curves
			3.3.10.1 Design Values for Traveled-Way Widening
			3.3.10.2 Application of Widening on Curves
		3.3.11 Widths for Turning Roadways at Intersections
			3.3.11.1 Three Cases
				3.3.11.1.1 Case I
				3.3.11.1.2 Case II
				3.3.11.1.3 Case III
			3.3.11.2 Design Values
			3.3.11.3 Widths Outside the Traveled Way
		3.3.12 Sight Distance on Horizontal Curves
			3.3.12.1 Stopping Sight Distance
			3.3.12.2 Passing Sight Distance
		3.3.13 General Controls for Horizontal Alignment
	3.4 VERTICAL ALIGNMENT
		3.4.1 Terrain
		3.4.2 Grades
			3.4.2.1 Vehicle Operating Characteristics on Grades
				3.4.2.1.1 Passenger Cars
				3.4.2.1.2 Trucks
				3.4.2.1.3 Recreational Vehicles
			3.4.2.2 Control Grades for Design
				3.4.2.2.1 Maximum Grades
				3.4.2.2.2 Minimum Grades
				3.4.2.2.3 Pedestrian Considerations
			3.4.2.3 Critical Lengths of Grade for Design
		3.4.3 Climbing Lanes
			3.4.3.1 Climbing Lanes for Two-Lane Highways
				3.4.3.1.1 General
				3.4.3.1.2 Trucks
				3.4.3.1.3 Summary
			3.4.3.2 Climbing Lanes on Freeways and Multilane Highways
				3.4.3.2.1 General
				3.4.3.2.2 Trucks
		3.4.4 Methods for Increasing Passing Opportunities on Two-Lane Roads
			3.4.4.1 Passing Lanes
			3.4.4.2 2+1 Roadways
			3.4.4.3 Turnouts
			3.4.4.4 Shoulder Driving
			3.4.4.5 Shoulder Use Sections
		3.4.5 Emergency Escape Ramps
			3.4.5.1 General
			3.4.5.2 Need and Location for Emergency Escape Ramps
			3.4.5.3 Types of Emergency Escape Ramps
			3.4.5.4 Design Considerations
			3.4.5.5 Brake-Check Areas
			3.4.5.6 Maintenance
		3.4.6 Vertical Curves
			3.4.6.1 General Considerations
			3.4.6.2 Crest Vertical Curves
				3.4.6.2.1 Design Controls: Stopping Sight Distance
				3.4.6.2.2 Design Controls: Passing Sight Distance
			3.4.6.3 Sag Vertical Curves
			3.4.6.4 Sight Distance at Undercrossings
			3.4.6.5 General Controls for Vertical Alignment
	3.5 COMBINATIONS OF HORIZONTAL AND VERTICAL ALIGNMENT
		3.5.1 General Considerations
		3.5.2 General Design Controls
		3.5.3 Alignment Coordination in Design
	3.6 OTHER FEATURES AFFECTING GEOMETRIC DESIGN
		3.6.1 Erosion Control and Landscape Development
		3.6.2 Rest Areas, Information Centers, and Scenic Overlooks
		3.6.3 Lighting
		3.6.4 Utilities
			3.6.4.1 General
			3.6.4.2 Rural Areas
			3.6.4.3 Urban Areas
		3.6.5 Traffic Control Devices
			3.6.5.1 Traffic Signs, Pavement Markings, and Traffic Signals
			3.6.5.2 Intelligent Transportation Systems
		3.6.6 Traffic Management Plans for Construction
	3.7 REFERENCES
CHAPTER 4 Cross-Section Elements
	4.1 GENERAL
	4.2 TRAVELED WAY
		4.2.1 Surface Type
		4.2.2 Cross Slope
			4.2.2.1 Rate of Cross Slope
			4.2.2.2 Weather Considerations
			4.2.2.3 Unpaved Surfaces
		4.2.3 Skid Resistance
		4.2.4 Hydroplaning
	4.3 LANE WIDTHS
	4.4 SHOULDERS
		4.4.1 General Characteristics
		4.4.2 Shoulder Width
		4.4.3 Shoulder Cross Sections
		4.4.4 Shoulder Stability
		4.4.5 Shoulder Contrast
		4.4.6 Turnouts
	4.5 RUMBLE STRIPS
	4.6 ROADSIDE DESIGN
		4.6.1 Clear Zones
		4.6.2 Lateral Offset
	4.7 CURBS
		4.7.1 General Considerations
		4.7.2 Curb Configurations
			4.7.2.1 Gutters
		4.7.3 Curb Placement
	4.8 DRAINAGE CHANNELS AND SIDESLOPES
		4.8.1 General Considerations
		4.8.2 Drainage
		4.8.3 Drainage Channels
		4.8.4 Sideslopes
	4.9 ILLUSTRATIVE OUTER CROSS SECTIONS
		4.9.1 Normal Crown Sections
		4.9.2 Superelevated Sections
	4.10 TRAFFIC BARRIERS
		4.10.1 General Considerations
		4.10.2 Longitudinal Barriers
			4.10.2.1 Roadside Barriers
			4.10.2.2 Median Barriers
		4.10.3 Bridge Railings
		4.10.4 Crash Cushions
	4.11 MEDIANS
	4.12 FRONTAGE ROADS
	4.13 OUTER SEPARATIONS
	4.14 ROADWAY TRAFFIC NOISE ABATEMENT
		4.14.1 General Considerations
		4.14.2 Noise Evaluation Procedures
		4.14.3 Noise Reduction
	4.15 ROADSIDE CONTROL
		4.15.1 General Considerations
		4.15.2 Driveways
		4.15.3 Mailboxes
		4.15.4 Fencing
	4.16 TUNNELS
		4.16.1 General Considerations
		4.16.2 Types of Tunnels
		4.16.3 General Design Considerations
		4.16.4 Tunnel Sections
		4.16.5 Examples of Tunnels
	4.17 PEDESTRIAN FACILITIES
		4.17.1 Sidewalks
		4.17.2 Grade-Separated Pedestrian Crossings
		4.17.3 Curb Ramps
	4.18 BICYCLE FACILITIES
	4.19 TRANSIT FACILITIES
		4.19.1 Bus Turnouts on Freeways
		4.19.2 Bus Turnouts on Arterials
		4.19.3 Park-and-Ride Facilities
			4.19.3.1 Location
			4.19.3.2 Design
	4.20 ON-STREET PARKING
	4.21 REFERENCES
CHAPTER 5 Local Roads and Streets
	5.1 INTRODUCTION
	5.2 LOCAL ROADS IN RURAL AREAS
		5.2.1 General Design Considerations
			5.2.1.1 Design Speed
			5.2.1.2 Design Traffic Volume
			5.2.1.3 Levels of Service
			5.2.1.4 Alignment
			5.2.1.5 Grades
			5.2.1.6 Cross Slope
		5.2.2 Cross-Sectional Elements
			5.2.2.1 Width of Roadway
			5.2.2.2 Number of Lanes
			5.2.2.3 Right-of-Way Width
			5.2.2.4 Medians
			5.2.2.5 Bicycle and Pedestrian Facilities
			5.2.2.6 Driveways
			5.2.2.7 Structures
				5.2.2.7.1 New and Reconstructed Structures
				5.2.2.7.2 Vertical Clearance
			5.2.2.8 Roadside Design
				5.2.2.8.1 Clear Zones
				5.2.2.8.2 Lateral Offset
				5.2.2.8.3 Foreslopes
			5.2.2.9 Intersection Design
			5.2.2.10 Railroad–Highway Grade Crossings
			5.2.2.11 Traffic Control Devices
			5.2.2.12 Drainage
			5.2.2.13 Erosion Control and Landscaping
			5.2.2.14 Design of Local Streets in the Rural Town Context
	5.3 LOCAL STREETS IN URBAN AREAS
		5.3.1 General Design Considerations
			5.3.1.1 Design Speed
			5.3.1.2 Design Traffic Volume
			5.3.1.3 Levels of Service
			5.3.1.4 Alignment
			5.3.1.5 Grades
			5.3.1.6 Cross Slope
			5.3.1.7 Superelevation
			5.3.1.8 Sight Distance
		5.3.2 Cross-Sectional Elements
			5.3.2.1 Width of Traveled Way
			5.3.2.2 Number of Lanes
			5.3.2.3 Parking Lanes
			5.3.2.4 Medians
			5.3.2.5 Curbs
			5.3.2.6 Right-of-Way Width
			5.3.2.7 Provision for Utilities
			5.3.2.8 Border Area
			5.3.2.9 Bicycle and Pedestrian Facilities
			5.3.2.10 Cul-de-Sacs and Turnarounds
			5.3.2.11 Alleys
			5.3.2.12 Driveways
		5.3.3 Structures
			5.3.3.1 New and Reconstructed Structures
			5.3.3.2 Vertical Clearance
		5.3.4 Roadside Design
			5.3.4.1 Clear Zones
			5.3.4.2 Lateral Offset
		5.3.5 Intersection Design
		5.3.6 Railroad–Highway Grade Crossings
		5.3.7 Traffic Control Devices
		5.3.8 Roadway Lighting
		5.3.9 Drainage
		5.3.10 Erosion Control
		5.3.11 Landscaping
	5.4 RECREATIONAL ROADS
		5.4.1 General Design Considerations
			5.4.1.1 Design Speed
			5.4.1.2 Design Vehicle
			5.4.1.3 Grades
			5.4.1.4 Vertical Alignment
			5.4.1.5 Horizontal Alignment and Superelevation
			5.4.1.6 Sight Distance
			5.4.1.7 Passing Sight Distance
			5.4.1.8 Cross Slope
		5.4.2 Cross-Sectional Elements
			5.4.2.1 Width of Roadway
			5.4.2.2 Number of Lanes
		5.4.3 Structures
		5.4.4 Roadside Design
			5.4.4.1 Clear Zones
			5.4.4.2 Roadside Slopes
			5.4.4.3 Roadside Barriers
		5.4.5 Signing and Marking
		5.4.6 Bicycle and Pedestrian Facilities
	5.5 RESOURCE RECOVERY AND LOCAL SERVICE ROADS
	5.6 LOW-VOLUME ROADS
	5.7 REFERENCES
CHAPTER 6 Collector Roads and Streets
	6.1 INTRODUCTION
	6.2 COLLECTORS IN RURAL AREAS
		6.2.1 General Design Considerations
			6.2.1.1 Design Speed
			6.2.1.2 Design Traffic Volumes
			6.2.1.3 Level of Service
			6.2.1.4 Alignment
			6.2.1.5 Grades
			6.2.1.6 Cross Slope
			6.2.1.7 Superelevation
			6.2.1.8 Sight Distance
		6.2.2 Cross-Sectional Elements
			6.2.2.1 Width of Roadway
			6.2.2.2 Number of Lanes
			6.2.2.3 Parking Lanes
			6.2.2.4 Medians
			6.2.2.5 Right-of-Way Width
			6.2.2.6 Bicycle/Pedestrian Facilities
		6.2.3 Structures
			6.2.3.1 New and Reconstructed Structures
			6.2.3.2 Vertical Clearance
		6.2.4 Roadside Design
			6.2.4.1 Clear Zones
			6.2.4.2 Lateral Offset
			6.2.4.3 Foreslopes
		6.2.5 Intersection Design
		6.2.6 Railroad–Highway Grade Crossings
		6.2.7 Traffic Control Devices
		6.2.8 Drainage
		6.2.9 Erosion Control and Landscaping
		6.2.10 Speed Transitions Entering Rural Towns
		6.2.11 Design of Collectors in the Rural Town Context
	6.3 COLLECTORS IN URBAN AREAS
		6.3.1 General Design Considerations
			6.3.1.1 Design Speed
			6.3.1.2 Design Traffic Volumes
			6.3.1.3 Level of Service
			6.3.1.4 Alignment
			6.3.1.5 Grades
			6.3.1.6 Cross Slope
			6.3.1.7 Superelevation
			6.3.1.8 Sight Distance
		6.3.2 Cross-Sectional Elements
			6.3.2.1 Width of Roadway
			6.3.2.2 Number of Lanes
			6.3.2.3 Parking Lanes
			6.3.2.4 Medians
			6.3.2.5 Curbs
			6.3.2.6 Right-of-Way Width
			6.3.2.7 Provision for Utilities
			6.3.2.8 Border Area
			6.3.2.9 Bicycle/Pedestrian Facilities
			6.3.2.10 Driveways
		6.3.3 Structures
			6.3.3.1 New and Reconstructed Structures
			6.3.3.2 Vertical Clearance
		6.3.4 Roadside Design
			6.3.4.1 Clear Zones
			6.3.4.2 Lateral Offset
		6.3.5 Intersection Design
		6.3.6 Railroad–Highway Grade Crossings
		6.3.7 Traffic Control Devices
		6.3.8 Roadway Lighting
		6.3.9 Drainage
		6.3.10 Erosion Control
		6.3.11 Landscaping
	6.4 REFERENCES
CHAPTER 7 Arterial Roads and Streets
	7.1 INTRODUCTION
	7.2 ARTERIALS IN RURAL AREAS
		7.2.1 General Characteristics
		7.2.2 General Design Considerations
			7.2.2.1 Design Speed
			7.2.2.2 Design Traffic Volumes
			7.2.2.3 Level of Service
			7.2.2.4 Sight Distance
			7.2.2.5 Alignment
			7.2.2.6 Grades
			7.2.2.7 Cross Slope
			7.2.2.8 Superelevation
		7.2.3 Cross-Sectional Elements
			7.2.3.1 Roadway Width
			7.2.3.2 Number of Lanes
			7.2.3.3 Cross Section and Right-of-Way
		7.2.4 Roadside Design
			7.2.4.1 Clear Zones
			7.2.4.2 Lateral Offset
		7.2.5 Structures
			7.2.5.1 Vertical Clearances
		7.2.6 Traffic Control Devices
		7.2.7 Erosion Control
		7.2.8 Provision for Passing
		7.2.9 Ultimate Development of Multilane Divided Arterials in Rural Areas
		7.2.10 Multilane Undivided Arterials in Rural Areas
		7.2.11 Divided Arterials in Rural Areas
			7.2.11.1 General Features
			7.2.11.2 Lane Widths
			7.2.11.3 Cross Slope
			7.2.11.4 Shoulders
			7.2.11.5 Median Barrier Clearance
			7.2.11.6 Medians
			7.2.11.7 Alignment and Profile
			7.2.11.8 Climbing Lanes on Multilane Arterials in Rural Areas
			7.2.11.9 Superelevated Cross Sections
			7.2.11.10 Cross Section and Right-of-Way Widths
			7.2.11.11 Sections with Widely Separated Roadways
		7.2.12 Intersections
		7.2.13 Access Management
		7.2.14 Bicycle and Pedestrian Facilities
		7.2.15 Bus Turnouts
		7.2.16 Railroad–Highway Grade Crossings
		7.2.17 Lighting
		7.2.18 Rest Areas
		7.2.19 Speed Transitions Entering Rural Towns
		7.2.20 Design of Arterials in the Rural Town Context
	7.3 ARTERIALS IN URBAN AREAS
		7.3.1 General Characteristics
		7.3.2 General Design Considerations
			7.3.2.1 Design Speed
			7.3.2.2 Design Traffic Volumes
			7.3.2.3 Level of Service
			7.3.2.4 Sight Distance
			7.3.2.5 Alignment
			7.3.2.6 Grades
			7.3.2.7 Superelevation
			7.3.2.8 Cross Slope
		7.3.3 Cross-Sectional Elements
			7.3.3.1 Roadway Widths
			7.3.3.2 Lane Widths
			7.3.3.3 Curbs and Shoulders
			7.3.3.4 Number of Lanes
			7.3.3.5 Medians
			7.3.3.6 Drainage
			7.3.3.7 Parking Lanes
			7.3.3.8 Borders and Sidewalks
			7.3.3.9 Right-of-Way Width
		7.3.4 Roadside Design
			7.3.4.1 Clear Zones
			7.3.4.2 Lateral Offset
		7.3.5 Structures
			7.3.5.1 New and Reconstructed Structures
			7.3.5.2 Vertical Clearances
		7.3.6 Traffic Barriers
		7.3.7 Railroad–Highway Grade Crossings
		7.3.8 Access Management
			7.3.8.1 General Features
			7.3.8.2 Access Control by Statute
			7.3.8.3 Access Control by Zoning
			7.3.8.4 Access Control through Driveway Regulations
			7.3.8.5 Access Control through Geometric Design
		7.3.9 Bicycle and Pedestrian Facilities
			7.3.9.1 Bicycle Facilities
			7.3.9.2 Pedestrian Facilities
		7.3.10 Provision for Utilities
		7.3.11 Intersection Design
		7.3.12 Operational Control
			7.3.12.1 Traffic Control Devices
			7.3.12.2 Provision and Management of Curb Parking
		7.3.13 Speed Management in Design
		7.3.14 Directional Lane Usage
			7.3.14.1 One-Way Operation
			7.3.14.2 Reverse-Flow Operation
		7.3.15 Frontage Roads and Outer Separations
		7.3.16 Grade Separations and Interchanges
		7.3.17 Erosion Control
		7.3.18 Lighting
		7.3.19 Public Transit Facilities
			7.3.19.1 Location of Bus Stops
			7.3.19.2 Bus Turnouts
			7.3.19.3 Reserved Bus Lanes
			7.3.19.4 Traffic Control Measures
	7.4 REFERENCES
CHAPTER 8 Freeways
	8.1 INTRODUCTION
	8.2 GENERAL DESIGN CONSIDERATIONS
		8.2.1 Design Speed
		8.2.2 Design Traffic Volumes
		8.2.3 Levels of Service
		8.2.4 Traveled Way and Shoulders
		8.2.5 Curbs
		8.2.6 Superelevation
		8.2.7 Grades
		8.2.8 Structures
		8.2.9 Vertical Clearance
		8.2.10 Roadside Design
		8.2.11 Ramps and Terminals
		8.2.12 Outer Separations, Borders, and Frontage Roads
	8.3 FREEWAYS IN RURAL AREAS
		8.3.1 Alignment and Profile
		8.3.2 Medians
		8.3.3 Sideslopes
		8.3.4 Frontage Roads
	8.4 FREEWAYS IN URBAN AREAS
		8.4.1 General Design Characteristics
		8.4.2 Medians
		8.4.3 Depressed Freeways
			8.4.3.1 General Characteristics
			8.4.3.2 Slopes and Walls
			8.4.3.3 Typical Cross Section
			8.4.3.4 Restrictive Cross Section
			8.4.3.5 Walled Cross Section
			8.4.3.6 Example of Depressed Freeway
		8.4.4 Elevated Freeways
			8.4.4.1 General Characteristics
			8.4.4.2 Medians
			8.4.4.3 Ramps and Terminals
			8.4.4.4 Frontage Roads
			8.4.4.5 Building Offset
			8.4.4.6 Typical Cross Section
			8.4.4.7 Freeways on Earth Embankment
			8.4.4.8 Examples of Elevated Freeways
		8.4.5 Ground-Level Freeways
			8.4.5.1 General Characteristics
			8.4.5.2 Typical Cross Section
			8.4.5.3 Restrictive Cross Section
			8.4.5.4 Example of a Ground-Level Freeway
		8.4.6 Combination-Type Freeways
			8.4.6.1 General Characteristics
			8.4.6.2 Profile Control
				8.4.6.2.1 Rolling Terrain
				8.4.6.2.2 Level Terrain
			8.4.6.3 Cross-Section Control
		8.4.7 Special Freeway Designs
			8.4.7.1 Reverse-Flow Roadways
			8.4.7.2 Dual-Divided Freeways
			8.4.7.3 Freeways with Collector–Distributor Roads
		8.4.8 Accommodation of Managed Lanes and Transit Facilities
			8.4.8.1 General Considerations
			8.4.8.2 Buses
				8.4.8.2.1 Exclusive HOV Lanes
				8.4.8.2.2 Bus Stops
				8.4.8.2.3 Bus-Stop Arrangements
				8.4.8.2.4 Bus Stops at Freeway Level
				8.4.8.2.5 Bus Stops at Street Level
				8.4.8.2.6 Stairs, Ramps, Escalators, and Elevators
			8.4.8.3 Rail Transit
				8.4.8.3.1 Typical Sections
				8.4.8.3.2 Stations
				8.4.8.3.3 Example of Rail Transit Combined with a Freeway
	8.5 REFERENCES
CHAPTER 9 Intersections
	9.1 INTRODUCTION
	9.2 GENERAL DESIGN CONSIDERATIONS AND OBJECTIVES
		9.2.1 Characteristics of Intersections
		9.2.2 Intersection Functional Area
		9.2.3 Design Objectives
		9.2.4 Design Considerations for Intersection User Groups
		9.2.5 Intersection Capacity
		9.2.6 Intersection Design Elements
	9.3 TYPES AND EXAMPLES OF INTERSECTIONS
		9.3.1 Three-Leg Intersections
			9.3.1.1 Basic Types of Intersections
			9.3.1.2 Channelized Three-Leg Intersections
		9.3.2 Four-Leg Intersections
			9.3.2.1 Basic Types
			9.3.2.2 Channelized Four-Leg Intersections
		9.3.3 Multileg Intersections
		9.3.4 Roundabouts
			9.3.4.1 Mini-Roundabouts
			9.3.4.2 Single-Lane Roundabouts
			9.3.4.3 Multilane Roundabouts
	9.4 ALIGNMENT AND PROFILE
		9.4.1 General Considerations
		9.4.2 Alignment
		9.4.3 Profile
	9.5 INTERSECTION SIGHT DISTANCE
		9.5.1 General Considerations
		9.5.2 Sight Triangles
			9.5.2.1 Approach Sight Triangles
			9.5.2.2 Departure Sight Triangles
			9.5.2.3 Identification of Sight Obstructions within Sight Triangles
		9.5.3 Intersection Control
			9.5.3.1 Case A—Intersections with No Control
			9.5.3.2 Case B—Intersections with Stop Control on the Minor Road
				9.5.3.2.1 Case B1—Left Turn from the Minor Road
				9.5.3.2.2 Case B2—Right Turn from the Minor Road
				9.5.3.2.3 Case B3—Crossing Maneuver from the Minor Road
			9.5.3.3 Case C—Intersections with Yield Control on the Minor Road
				9.5.3.3.1 Case C1—Crossing Maneuver from the Minor Road
				9.5.3.3.2 Case C2—Left- and Right-Turn Maneuvers
			9.5.3.4 Case D—Intersections with Traffic Signal Control
			9.5.3.5 Case E—Intersections with All-Way Stop Control
			9.5.3.6 Case F—Left Turns from the Major Road
			9.5.3.7 Case G—Roundabouts
		9.5.4 Effect of Skew
	9.6 TURNING ROADWAYS AND CHANNELIZATION
		9.6.1 Turning Roadways
			9.6.1.1 General
			9.6.1.2 Channelized Right-Turn Lanes
			9.6.1.3 Design Considerations
			9.6.1.4 Curb Radius
		9.6.2 Channelization
		9.6.3 Islands
			9.6.3.1 General Characteristics
			9.6.3.2 Channelizing Islands
			9.6.3.3 Divisional Islands
			9.6.3.4 Refuge Islands
			9.6.3.5 Island Size and Designation
			9.6.3.6 Island Delineation and Approach Treatment
			9.6.3.7 Corner Islands for Turning Roadways
		9.6.4 Superelevation for Turning Roadways at Intersections
			9.6.4.1 General Design Guidelines
			9.6.4.2 Superelevation Runoff
			9.6.4.3 Development of Superelevation at Turning Roadway Terminals
		9.6.5 Stopping Sight Distance at Intersections for Turning Roadways
			9.6.5.1 General Considerations
			9.6.5.2 Vertical Control
			9.6.5.3 Horizontal Control
	9.7 AUXILIARY LANES
		9.7.1 General Design Considerations
		9.7.2 Deceleration Lanes
			9.7.2.1 Perception–Reaction Distance
			9.7.2.2 Storage Length
			9.7.2.3 Taper Length
		9.7.3 Design Treatments for Left-Turn Maneuvers
			9.7.3.1 Guidelines for Provision and Design of Left-Turn and Bypass Lanes
			9.7.3.2 Median Left-Turn Lanes
			9.7.3.3 Median End Treatment
			9.7.3.4 Offset Left-Turn Lanes
			9.7.3.5 Simultaneous Left Turns
			9.7.3.6 Double or Triple Left-Turn Lanes
	9.8 MEDIAN OPENINGS
		9.8.1 General Design Considerations
		9.8.2 Control Radii for Minimum Turning Paths
			9.8.2.1 Shape of Median End
		9.8.3 Effect of Skew
		9.8.4 Design Considerations for Higher Speed Left Turns
	9.9 INDIRECT LEFT TURNS AND U-TURNS
		9.9.1 General Design Considerations
		9.9.2 Intersections with Jughandle or Loop Roadways
		9.9.3 Displaced Left-Turn Intersections
		9.9.4 Wide Medians with U-Turn Crossover Roadways
		9.9.5 Location and Design of U-Turn Median Openings
	9.10 ROUNDABOUT DESIGN
		9.10.1 Geometric Elements of Roundabouts
			9.10.1.1 Size and Space Needs
		9.10.2 Fundamental Principles
			9.10.2.1 Slow Speeds Using Deflection
			9.10.2.2 Lane Balance and Lane Continuity
			9.10.2.3 Appropriate Natural Path Alignment
			9.10.2.4 Design Vehicle
			9.10.2.5 Nonmotorized Users
			9.10.2.6 Sight Distance and Visibility
	9.11 OTHER INTERSECTION DESIGN CONSIDERATIONS
		9.11.1 Intersection Design Elements with Frontage Roads
		9.11.2 Traffic Control Devices
		9.11.3 Bicyclists
		9.11.4 Pedestrians
		9.11.5 Lighting
		9.11.6 Driveways
		9.11.7 Left Turns at Midblock Locations and at Unsignalized Intersections on Streets with Flush Medians
	9.12 RAILROAD–HIGHWAY GRADE CROSSINGS
		9.12.1 Horizontal Alignment
		9.12.2 Vertical Alignment
		9.12.3 Crossing Design
		9.12.4 Sight Distance
	9.13 REFERENCES
CHAPTER 10 Grade Separations and Interchanges
	10.1 INTRODUCTION AND GENERAL TYPES OF INTERCHANGES
	10.2 WARRANTS FOR INTERCHANGES AND GRADE SEPARATIONS
	10.3 ADAPTABILITY OF HIGHWAY GRADE SEPARATIONS AND INTERCHANGES
		10.3.1 Traffic and Operation
		10.3.2 Site Conditions
		10.3.3 Type of Highway and Intersecting Facility
	10.4 ACCESS SEPARATIONS AND CONTROL ON THE CROSSROAD AT INTERCHANGES
	10.5 SAFETY
	10.6 STAGE DEVELOPMENT
	10.7 ECONOMIC FACTORS
		10.7.1 Initial Costs
		10.7.2 Maintenance Costs
		10.7.3 Vehicular Operating Costs
	10.8 GRADE SEPARATION STRUCTURES
		10.8.1 Introduction
		10.8.2 Types of Separation Structures
		10.8.3 Overpass versus Underpass Roadways
			10.8.3.1 General Design Considerations
			10.8.3.2 Structure Widths
		10.8.4 Underpass Roadways
			10.8.4.1 Lateral Offset
			10.8.4.2 Vertical Clearance
		10.8.5 Overpass Roadways
			10.8.5.1 Bridge Railings
			10.8.5.2 Lateral Offset
			10.8.5.3 Medians
		10.8.6 Longitudinal Distance to Attain Grade Separation
		10.8.7 Grade Separations without Ramps
	10.9 INTERCHANGES
		10.9.1 General Considerations
		10.9.2 Three-Leg Designs
		10.9.3 Four-Leg Designs
			10.9.3.1 Ramps in One Quadrant
			10.9.3.2 Diamond Interchanges
			10.9.3.3 Roundabout Interchanges
			10.9.3.4 Single-Point Diamond Interchanges
			10.9.3.5 Diverging Diamond Interchanges
			10.9.3.6 Cloverleaf Interchanges
				10.9.3.6.1 Partial Cloverleaf Ramp Arrangements
			10.9.3.7 Directional Interchanges
				10.9.3.7.1 With Loops and Weaving
				10.9.3.7.2 With Loops and No Weaving
				10.9.3.7.3 Fully Directional
		10.9.4 Other Interchange Configurations
			10.9.4.1 Offset Interchanges
			10.9.4.2 Combination Interchanges
		10.9.5 General Design Considerations
			10.9.5.1 Determination of Interchange Configuration
			10.9.5.2 Approaches to the Structure
				10.9.5.2.1 Alignment, Profile, and Cross Section
				10.9.5.2.2 Sight Distance
			10.9.5.3 Interchange Spacing
			10.9.5.4 Uniformity of Interchange Patterns
			10.9.5.5 Route Continuity
			10.9.5.6 Overlapping Routes
			10.9.5.7 Signing and Marking
			10.9.5.8 Basic Number of Lanes
			10.9.5.9 Coordination of Lane Balance and Basic Number of Lanes
			10.9.5.10 Auxiliary Lanes
			10.9.5.11 Lane Reductions
			10.9.5.12 Weaving Sections
			10.9.5.13 Collector–Distributor Roads
			10.9.5.14 Two-Exit versus Single-Exit Interchange Design
			10.9.5.15 Wrong-Way Entry
		10.9.6 Ramps
			10.9.6.1 Types and Examples
			10.9.6.2 General Ramp Design Considerations
				10.9.6.2.1 Design Speed
				10.9.6.2.2 Portion of Ramp to Which Design Speed Is Applicable
				10.9.6.2.3 Ramps for Right Turns
				10.9.6.2.4 Loop Ramps
				10.9.6.2.5 Two-Lane Loop Ramps
				10.9.6.2.6 Semidirect Connections
				10.9.6.2.7 Direct Connections
				10.9.6.2.8 Different Design Speeds on Intersecting Highways
				10.9.6.2.9 At-Grade Terminals
				10.9.6.2.10 Curvature
				10.9.6.2.11 Sight Distance
				10.9.6.2.12 Grade and Profile Design
				10.9.6.2.13 Vertical Curves
				10.9.6.2.14 Superelevation and Cross Slope
				10.9.6.2.15 Gores
			10.9.6.3 Ramp Traveled-Way Widths
				10.9.6.3.1 Width and Cross Section
				10.9.6.3.2 Shoulder Widths and Lateral Offset
				10.9.6.3.3 Shoulders and Curbs
			10.9.6.4 Ramp Terminals
				10.9.6.4.1 Left-Side Entrances and Exits
				10.9.6.4.2 Terminal Location and Sight Distance
				10.9.6.4.3 Ramp Terminal Design
				10.9.6.4.4 Traffic Control
				10.9.6.4.5 Distance between a Free-Flow Terminal and Structure
				10.9.6.4.6 Distance between Successive Ramp Terminals
				10.9.6.4.7 Speed-Change Lanes
			10.9.6.5 Single-Lane Free-Flow Terminals, Entrances
				10.9.6.5.1 Taper-Type Entrances
				10.9.6.5.2 Parallel-Type Entrances
			10.9.6.6 Single-Lane Free-Flow Terminals, Exits
				10.9.6.6.1 Taper-Type Exits
				10.9.6.6.2 Parallel-Type Exits
				10.9.6.6.3 Free-Flow Terminals on Curves
				10.9.6.6.4 Multilane Free-Flow Terminals
				10.9.6.6.5 Two-Lane Entrances
				10.9.6.6.6 Two-Lane Exits
				10.9.6.6.7 Two-Lane Terminals on Curved Alignment
				10.9.6.6.8 Major Forks and Branch Connections
		10.9.7 Other Interchange Design Features
			10.9.7.1 Testing for Ease of Operation
			10.9.7.2 Pedestrian and Bicycle Accommodation
			10.9.7.3 Managed Lanes and Transit Facilities
			10.9.7.4 Ramp Metering
			10.9.7.5 Grading and Landscape Development
				10.9.7.5.1 Contour Grading Design
				10.9.7.5.2 Plantings
			10.9.7.6 Models
		10.10 REFERENCES
Index