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Publication Number: FHWA-HRT-04-091
Date: August 2004

The July 2013 - FHWA-SA-13-027 - 'Signalized Intersections: An Informational Guide' supercedes the following document.

 

Signalized Intersections: Informational Guide

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Table of Contents

FOREWORD

This report complements the American association of State Highway and Transportation Officials' (AASHTO) Strategic Highway Safety Plan to develop guidance on safety of nonsignalized and signalized intersections. The goal is to reduce the annual number of highway deaths. This guide is a comprehensive document that contains methods for evaluating the safety and operations of signalized intersections and tools to remedy deficiencies. The treatments in this guide range from low-cost measures such as improvements to signal timing and signage, to high-cost measures such as intersection reconstruction or grade separation. Topics covered include fundamental principles of user needs, geometric design, and traffic design and operation; safety and operational analysis techniques; and a wide variety of treatments to address existing or projected problems, including individual movements and approaches, pedestrian and bicycle treatments, and corridor techniques. It also includes coverage of alternative intersection forms that improve intersection performance through the use of indirect left turns and other treatments. Each treatment includes a discussion of safety, operational performance, multimodal issues, and physical and economic factors that the practitioner should consider. Although the guide has considerable focus on high-volume signalized intersections, many treatments also are applicable for lower volume intersections. The information contained in this guide is based on the latest research on available treatments and best practices in use by jurisdictions across the United States. Additional resources and references are highlighted for the student, practitioner, researcher, or decisionmaker who wishes to learn more about a particular subject.

Copies of this report may be obtained from the Research and technology Report Center, 9701 Philadelphia Court, Unit Q, Lanham, MD 20706; telephone: 301–577–0818; fax: 301–577–1421; or the National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161; telephone: 703–487–4650; fax: 703–321–8547.

Michael F. Trentacoste
Director
Office of Safety Research and Development 

 

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.




Technical Report Documentation Page

1. Report No.
FHWA-HRT-04-091

2. Government accession No.

3. Recipient's Catalog No.

4. Title and Subtitle
Signalized Intersections: Informational Guide

5. Report Date
August 2004

6. Performing Organization Code

 

7. Author(s)

Principal Investigator: Lee A. Rodegerdts

Co-Investigators: Brandon Nevers, Bruce Robinson

Co-Authors: John Ringert, Peter Koonce, Justin Bansen, Tina Nguyen, John McGill, Del Stewart, Jeff Suggett, Tim Neuman, Nick Antonucci, Kelly Hardy, Ken Courage

8. Performing Organization Report No.

Project 4770

9. Performing Organization Name and Address

Kittelson & Associates, Inc.
610 SW Alder Street, Suite 700
Portland, OR 97205

Subconsultants: Synectics transportation Consultants, Inc.; CH2M Hill, Inc.; and Ken Courage

10. Work Unit No. (TRAIS)

 

11. Contract or Grant No.

Contract No. DTFH61-98-C-00075,
Task Order No. B98C75-009

12. Sponsoring Agency Name and Address

Federal Highway Administration
Turner-Fairbank Highway Research Center
6300 Georgetown Pike, HSR 20, Room No. T301
McLean, VA 22101

13. Type of Report and Period Covered

Informational Guide Book
October 2001 to June 2004

 

14. Sponsoring Agency Code

15. Supplementary Notes

Joe G. Bared (Joe.Bared@fhwa.dot.gov) at the turner-Fairbank Highway Research Center (http://www.fhwa.dot.gov/research/tfhrc/) was the technical Representative for the Federal Highway Administration (FHWA). Project focus group members contributed significantly to document organization, content, and exhibits: Tom Hicks, Maryland State Highway Administration; Nick Kalivoda, Louisiana Department of Transportation; Nazir Lalani, Ventura County (California); John Mason, Pennsylvania State University; and brian Walsh, Washington State Department of Transportation. In addition, many FHWA staff members participated as focus group members and/or provided comments throughout the project, including Carl Andersen, David Gibson, Hari Kalla, Ray Krammes, Barbara McMillen, Bill Prosser, fred Ranck, Tamara Redmon, Essie Wagner, and Scott Wainwright.

16. Abstract

This guide provides a single, comprehensive document with methods for evaluating the safety and operations of signalized intersections and tools to remedy deficiencies. The treatments in this guide range from low-cost measures such as improvements to signal timing and signage, to high-cost measures such as intersection reconstruction or grade separation. Topics covered include fundamental principles of user needs, geometric design, and traffic design and operation; safety and operational analysis techniques; and a wide variety of treatments to address existing or projected problems, including individual movements and approaches, pedestrian and bicycle treatments, and corridor techniques. It also covers alternative intersection forms that improve intersection performance through the use of indirect left turns and other treatments. Each treatment includes a discussion of safety, operational performance, multimodal issues, and physical and economic factors that the practitioner should consider. Although the guide focuses primarily on high-volume signalized intersections, many treatments are applicable for lower volume intersections as well. The information contained in this guide is based on the latest research available on treatments and best practices in use by jurisdictions across the United States. Additional resources and references are highlighted for the student, practitioner, researcher, or decisionmaker who wishes to learn more about a particular subject.

17. Key words
Signalized Intersections, Intersection Safety, Intersection Design, Intersection performance, Intersection Treatments

18. Distribution Statement

 

19. Security Classif. (of this report)
Unclassified

20. Security Classif. (of this page)
Unclassified

21. No. of Pages
371

Form DOT F 1700.7 (8-72)   Reproduction of completed page authorized




TABLE OF CONTENTS

1.0 INTRODUCTION

1.1 Background

1.2 Scope of Guide

1.3 Audience for this Guide

1.4 Organization of the Guidelines

PART I FUNDAMENTALS

2.0 ROAD USER NEEDS

2.1 Overview of Human Factors

2.1.1 Positive Guidance

2.1.2 Roadway Safety

2.2 Intersection Users

2.2.1 Human Factors Common to All Road Users

2.2.2 Motorists

2.2.3 Bicyclists

2.2.4 Pedestrians

2.3 Applying Human Factors

 

3.0 GEOMETRIC DESIGN

3.1 Channelization

3.2 Number of Intersection Legs

3.3 Intersection angle

3.4 Horizontal and Vertical Alignment

3.5 Corner Radius and Curb Ramp Design

3.5.1 Corner Radius

3.5.2 Curb Ramp Design

3.5.3  Detectable Warnings

3.6 Sight Distance

3.6.1 Stopping Sight Distance

3.6.2 Decision Sight Distance

3.6.3 Intersection Sight Distance

3.7 Pedestrian Facilities

3.8 Bicycle Facilities

 

4.0 TRAFFIC DESIGN AND ILLUMINATION

4.1 Traffic Signal Control Type

4.2 Traffic Signal Phasing

4.2.1 "Permissive-Only" Left-Turn phasing

4.2.2 "Protected-Only" Left-Turn phasing

4.2.3 Protected-Permissive Left-Turn phasing

4.2.4 Split Phasing

4.2.5 Prohibited Left-Turn phasing

4.2.6 Right-Turn phasing

4.3 Vehicle and Pedestrian Displays

4.3.1 Vehicle Displays

4.3.2 Pedestrian Displays

4.4 Traffic Signal Pole Layout

4.5 Traffic Signal Controller

4.6 Detection Devices

4.6.1 Vehicle Detection

4.6.2 Pedestrian Detection

4.7 Basic Signal Timing parameters

4.7.1 Pedestrian Timing

4.7.2 Vehicle timing—Green interval

4.7.3 Vehicle timing—Detector Timing

4.7.4 Vehicle timing—Vehicle Clearance

4.7.5 Vehicle timing—Cycle Length

4.8 Signing and Pavement Marking Design

4.9 Illumination Design

4.9.1 Illuminance

4.9.2 Veiling Illuminance

 

PART II PROJECT PROCESS ANALYSIS METHODS

 

5.0 PROJECT PROCESS

5.1   Project initiation

5.2   Identify Stakeholder Interests and Objectives

5.2.1 Intersection Users

5.2.2 Adjacent Property/Business owners

5.2.3 Facility Managers

5.2.4 Other Decisionmakers

5.3 Data Collection

5.3.1 Office Review

5.3.2 Field Investigation

5.4 Problem Identification

5.4.1 Establish Performance Measures and Criteria

5.4.2 Summarize Operational and Safety Conditions

5.4.3 Develop Problem Statement

5.5 Identify Problem Cause

5.6 treatment selection

5.6.1 Identify Range of Treatments

5.6.2 Evaluate treatments.

5.6.3 Assess Potential To Introduce Undesirable Effects

5.6.4 Determine Costs and Implementation issues

5.7 In-Service Assessments

5.7.1 Followup Plan

5.7.2 Monitoring program

 

6.0 SAFETY ANALYSIS METHODS

6.1 Balancing Safety and Mobility

6.2 Selection of an intersection

6.2.1 Collision Frequency

6.2.2 Collision Rate

6.2.3 Combined Collision Frequency and Rate Method

6.2.4 Collision Severity Method

6.2.5 Critical Collision Rate

6.2.6 Risk Analysis Methods

6.2.7 Safety Performance Functions

6.2.8 Empirical bayes Method

6.2.9 Conclusions

6.3 Identification of Potential Problems

6.3.1 Safety Diagnosis

6.3.2 Assemble Collision Data

6.3.3 Analyze/Diagnose Collision Data

6.3.4 Determine Overrepresentation

6.3.5 Conduct Site Visit(s)

6.3.6 Deciding on Further Analysis

6.3.7 Conducting Further Studies

6.3.8 Defining the Problem Statement

6.4 Identification of Possible Treatments

6.4.1 List Possible Treatments

6.4.2 Screen Treatments

6.4.3 Selecting a Collision Modification Factor or Study Finding

6.4.4 Quantify Safety Benefit

6.4.5 Selected treatment(s)

6.5 Improvement Plan Development

7.0 OPERATIONAL ANALYSIS METHODS

7.1 Operational measures of Effectiveness

7.1.1 Motor Vehicle Capacity and Volume-to-Capacity Ratio

7.1.2 Motor vehicle Delay and Level of Service

7.1.3 Motor vehicle Queue

7.1.4 Transit Level of Service

7.1.5 Bicycle Level of Service

7.1.6 Pedestrian Level of Service

7.2 Traffic Operations Elements

7.2.1 Traffic Volume Characteristics

7.2.2 Intersection Geometry

7.2.3 Signal Timing

7.3 Rules of Thumb for Sizing an intersection

7.4 Critical movement analysis

7.5 HCM Operational Procedure for Signalized Intersections

7.6 Arterial and Network Signal Timing Models

7.7 Microscopic Simulation Models

 

PART III TREATMENTS

8.0 SYSTEM-WIDE TREATMENTS

8.1 Median Treatments

8.1.1 Description

8.1.2 Applicability

8.1.3 Key Design Features

8.1.4 Safety Performance

8.1.5 Operational Performance

8.1.6 Multimodal Impacts

8.1.7 Physical Impacts

8.1.8 Socioeconomic Impacts

8.1.9 Enforcement, Education, and maintenance

8.1.10   Summary

8.2 Access Management

8.2.1 Description

8.2.2 Applicability

8.2.3 Design Features

8.2.4 Safety Performance

8.2.5 Operational Performance

8.2.6 Multimodal Impacts

8.2.7 Physical Impacts

8.2.8 Socioeconomic Impacts

8.2.9 Enforcement, Education, and maintenance

8.2.10 Summary

8.3 Signal Coordination

8.3.1 Description

8.3.2 Applicability

8.3.3 Safety Performance

8.3.4 Operational Performance

8.3.5 Multimodal Impacts

8.3.6 Physical Impacts

8.3.7 Socioeconomic Impacts

8.3.8 Enforcement, Education, and maintenance

8.3.9 Summary

8.4 Signal Preemption and/or Priority

8.4.1 Description

8.4.2 Emergency Vehicle Preemption

8.4.3 Applicability

8.4.4 Safety Performance

8.4.5 Operational Performance

8.4.6 Multimodal Impacts

8.4.7 Physical Impacts

8.4.8 Socioeconomic Impacts

8.4.9 Enforcement, Education, and Maintenance

8.4.10   Summary

 

9.0 INTERSECTION-WIDE TREATMENTS

9.1 Pedestrian Treatments

9.1.1 Reduce Curb Radius

9.1.2 Provide Curb Extensions

9.1.3 Modify Stop Bar Location

9.1.4 Improve Pedestrian Signal Displays

9.1.5 Modify Pedestrian Signal Phasing

9.1.6 Grade-Separate Pedestrian Movements

9.2 Bicycle treatments

9.2.1 Provide Bicycle Box

9.2.2 Provide Bike Lanes

9.3 Transit treatments

9.3.1 Relocate transit Stop

9.4 Traffic Control Treatments

9.4.1 Change signal Control from Pre-Timed to Actuated

9.4.2 Modify Yellow Change interval and/or Red Clearance interval

9.4.3 Modify Cycle Length

9.4.4 Late Night/Early Morning Flash Removal

9.5 Street Lighting and Illumination

9.5.1 Provide or Upgrade illumination

 

10.0 ALTERNATIVE INTERSECTION TREATMENTS

10.1    Intersection Reconfiguration and Realignment treatments

10.1.1 Remove intersection Skew Angle

10.1.2 Remove Deflection in Travel Path for Through Vehicles

10.1.3 Convert four-Leg Intersection to Two T-Intersections

10.1.4 Convert two T-Intersections to Four-Leg Intersection

10.1.5 Close intersection Leg

10.2 Indirect Left-Turn Treatments

10.2.1 Jughandle

10.2.2 Median U-Turn Crossover

10.2.3 Continuous Flow Intersection

10.2.4 Quadrant Roadway intersection

10.2.5 Super-Street Median Crossover

10.3 Grade-Separation Treatments

10.3.1 Split intersection

10.3.2 Diamond Interchange

 

11.0 APPROACH TREATMENTS

11.1 Signal Head Placement and Visibility

11.1.1 Convert to Mast arm or Span Wire Mounted Signal Heads

11.1.2 Add Near-Side signal Heads

11.1.3 Increase size of Signal Heads

11.1.4 Use two Red Signal Sections

11.1.5 Increase Number of Signal Heads

11.1.6 Provide Backplates

11.1.7 Provide Advance Warning

11.2 Signing and Speed Control Treatments

11.2.1 Improve signing

11.2.2 Reduce Operating Speed

11.3 Roadway Surface Improvements

11.3.1 Improve Pavement Surface

11.3.2 Provide Rumble strips

11.3.3 Improve Cross section

11.3.4 Remove Obstacles from Clear Zone

11.4 Sight Distance Treatments

11.4.1 Improve Sight Lines

 

12.0 INDIVIDUAL MOVEMENT TREATMENTS

12.1 Left-Turn Treatments

12.1.1 Add Single Left-Turn Lane

12.1.2 Multiple Left-Turn Lanes

12.1.3 Turn prohibition

12.2 Through Lane treatments

12.2.1 Provide Auxiliary Through Lanes

12.2.2 Delineate through Path

12.3 Right-Turn Treatments

12.3.1 Add Single Right-Turn Lane

12.3.2 Provide Double Right-Turn Lanes

12.3.3 Provide Channelized Right-Turn Lane

12.4 Variable Lane Use Treatments

12.4.1 Provide Reversible Lanes

12.4.2 Provide Variable Lane Use Assignments

 

REFERENCES

 

BIBLIOGRAPHY (OTHER REFERENCES)

 

LIST OF FIGURES

CHAPTER 2

1

Traffic controls such as official signs need to be close to the road, distinctive from other information presentations, brief, and explicit. This photo provides an example  of signs that are close to the road but may be confused with background information.

2

In terms of both official signs and advertising displays, too many displays may have the  effect of causing drivers to "tune out," and recall will be poor. This photo shows an example of sign clutter where the regulatory sign is difficult to isolate from the background advertising signs.

3

Enforcement cameras, as shown in the photo above, are used at signalized intersections to identify red light runners

4

Typical dimensions of a bicyclist

5

Bicyclist conflicts at signalized intersections

6

Examples of pedestrians of various abilities preparing to cross an intersection

7

Typical dimensions for a turning wheelchair

8

Crosswalks are used by a variety of users with different speed characteristics. Pedestrian walking speeds generally range between 0.8 to 1.8 m/s (2.5 to 6.0 ft/s)

9
Pedestrian conflicts at signalized intersections

 

CHAPTER 3

10
The photograph shows a raised median that restricts left-turn egress movements from a driveway located between two signalized intersections
11
Pavement markings can be used to delineate travel lanes within wide intersections as shown in the photograph
12
Various right-turn treatments may be used, depending on the speed environment
13

Providing a dedicated left-turn lane reduces potential collisions between left-turning and through vehicles, increasing the capacity of the approach for both left and through traffic

14
The photo shows how double left-turn and double right-turn lanes can be used to accommodate high-priority movements
15
Intersection skews increase both the intersection width and pedestrian crossing distance
16 
The photograph illustrates a multileg intersection
17
Potential conflicts at intersections with three and four legs
18
Curb ramp components
19
Examples of preferred designs
20
Examples of acceptable curb ramp designs
21
Examples of inaccessible designs
22
This crosswalk design incorporates the use of detectable warning surfaces into the curb ramps to facilitate navigation by a visually impaired pedestrian

 

CHAPTER 4

23

Standard NEMA ring-and-barrier structure

24
Typical phasing diagram for "permissive-only" left-turn phasing
25
Possible signal head arrangements for "permissive-only" left-turn phasing
26
Typical phasing diagram for "protected-only" left-turn phasing
27
Possible signal head arrangements for "protected-only" left-turn phasing
28
Typical phasing diagram for protected-permissive left-turn phasing
29
Possible signal head and signing arrangement for protected-permissive left-turn phasing
30 
Illustration of the yellow trap
31
The protected-permissive left-turn display known as "Dallas display" uses louvers to  restrict visibility of the left-turn display to adjacent lanes
32
Typical phasing diagrams for split phasing
33
Common signal head arrangement for split phasing
34
Typical phasing diagram illustrating a right-turn overlap
35
Common signal head and signing arrangement for right-turn-overlap phasing
36
Examples showing five optional signal head locations
37
Pedestrian signal indicators
38
Example of advance street name sign for upcoming intersection
39 
Example of advance street name sign for two closely spaced intersections
40
Example of signing for a left-hand land trap
41
Example of advance overhead signs indicating lane use for various destinations
42
Example of pavement legends indicating destination route numbers ("horizontal signage") 

 

CHAPTER 6

43

Exclusion of property-damage-only collisions (such as this one from an analysis) may  mask valuable information

44

The potential for error in coding the location of a collision should be understood

45
Selecting a candidate intersection using a combined collision frequency/collision rate method, where each diamond represents an intersection
46
Example of SPF curve
47
Identification of potential problems
48
The original police collision report may contain valuable information regarding collisions that have occurred at the intersection
49
Possible taxonomy for collision type classification
50
Conducting a site visit
51
Examples of problem statements
52
Identification of possible treatments

 

CHAPTER 7

53
Still reproduction of a graphic from an animated traffic operations model
54
Overview of intersection traffic analysis models
55
Pedestrian LOs based on cycle length and minimum effective pedestrian green time
56
Graphical summary of the Quick Estimation

 

CHAPTER 8

57
Issues associated with intersections with a narrow median
58
Issues associated with intersections with a wide median
59
Median pedestrian treatments
60
Median pedestrian signal treatments
61
This refuge island enables two-stage pedestrian crossings
62
Comparison of physical and functional areas of an intersection
63
Diagram of the upstream functional area of an intersection
64
Access points near signalized intersections
65
Access management requiring U-turns at a downstream signalized intersection
66
Access management requiring U-turns at an unsignalized, directional median opening

 

CHAPTER 9

67
A curb radius from 4.6 m (15 ft) to 15.2 m (50 ft) increases the pedestrian crossing distance from 18.9 m (62 ft) to 30.5 m (100 ft), all else being equal
68
Intersection with curb extension
69
Examples of countdown and animated eyes pedestrian signal displays
70
A pedestrian grade separation treatment
71
Typical lighting layouts

 

CHAPTER 10

72
Illustration of conflict points for a four-leg signalized intersection
73
Diagrams of different types of intersection realignment
74
Example of deflection in travel paths for through vehicles
75
Conflict point diagram for two closely spaced t-intersections
76
Diagram of a jughandle intersection
77
Vehicular movements at a jughandle intersection
78
Example of a jughandle intersection
79
Another example of a jughandle intersection
80
Design layout of near-side jughandle
81
Design layout of far-side jughandle
82
Example of jughandle and associated signing
83
Signal phasing of a jughandle intersection
84
Conflict point diagram for a four-leg signalized intersection with two jughandles
85
Diagram of a median U-turn crossover from the main line
86
Vehicular movements at a median U-turn intersection
87
Example of median U-turn signing in Michigan
88
Diagram of general placement of a median U-turn crossover
89
Diagram of a median U-turn crossover from the main line with a narrow median
90
Conflict diagram for a four-leg signalized intersection with median U-turns
91
Diagram of a continuous flow intersection
92
Vehicular movements at a continuous flow intersection
93
Continuous flow intersection
94
Displaced left turn at a continuous flow intersection
95
Signal phasing of a continuous flow intersection
96
Conflict diagram for a continuous flow intersection with displaced left turns on the major street only
97
Diagram of a quadrant roadway intersection
98
Vehicular movements at a quadrant roadway intersection
99
Signal phasing of a quadrant roadway intersection
100
Conflict point diagram for four-leg signalized intersection with quadrant roadway
101
Illustration of super-street median crossover
102
Vehicular movements at a super-street median crossover
103
Signal phasing of a super-street median crossover
104
Conflict diagram for a super-street median crossover
105
Illustration of a split intersection
106
Conflict point diagram for a split intersection
107
Diagram of a single-point interchange
108
Diagram of a compressed diamond interchange
109
Typical signal phasing of a single-point interchange
110
Typical signal phasing of a compressed diamond interchange
111
Single-point diamond interchange conflict point diagram
112
Compressed diamond interchange conflict point diagram

 

CHAPTER 11
113
Signal head with a double red signal indication
114
Lane-aligned signal heads
115
Illustration of sight distance triangles

 

CHAPTER 12

116
Diagram of a single left-turn lane
117
Narrow (2.4-m (8-ft) left-turn lanes may be used effectively in retrofit situations
118
Example of positive offset
119
Intersection with turn paths delineated for dual left-turn lanes in Tucson, AZ (Kolb Road/22nd Street), June 1998
120
Diagram of an auxiliary through lane
121
Example of delineated paths
122
Diagram of a typical right-turn lane
123
Narrow (2.4-m (8-ft) right-turn lanes may be used effectively in retrofit situations
124
Example illustration of a channelized right-turn lane
125
Example use of variable lane use sign to add a third left-turn lane during certain times of day
126
Example use of variable lane use sign to add a second right-turn lane along a corridor  during certain times of day

 

LIST OF TABLES

  

CHAPTER 1

1

Summary of motor vehicle crashes related to junction and severity in the United States during 2002

2
Organization of the guide
3

List of intersection treatments discussed in this document

 

CHAPTER 2

4

Estimated number of registered vehicles by type, 2002

5

Fatalities and injuries by mode, 2001

6

Total motor vehicle crashes and injury/fatal collisions at signalized intersections by total ADT entering the intersection

7

Proportion of crashes by collision type at signalized intersections

8
Typical dimensions for a sample of types of pedestrians

 

CHAPTER 3

Summary of best practices for curb ramp design and associated rationale
10
Requirements for detectable warning surfaces
11
Design values for stopping sight distance
12
Design values for decision sight distance for selected avoidance maneuvers

 

CHAPTER 4

13
Advantages and disadvantages of various configurations for displaying vehicle signal  indications
14
Traffic signal controller advantages and disadvantages
15
Strengths and weaknesses of commercially available detector technologies
16
Location of advanced vehicle detectors
17
Recommended illuminance for the intersection of continuously lighted urban streets
18
RP-8-00 guidance for roadway and pedestrian/area classification for purposes of  determining intersection illumination levels

 

CHAPTER 5

19

Example stakeholder interests and objectives

20  User characteristics
21 Operational characteristics
22 Safety characteristics
23 Geometric, traffic signal control, and land use characteristics
24  Policy and background information
25 Common concerns raised by stakeholders
26  Example performance measures and criteria
27  Possible causes of intersection problems

 

CHAPTER 6

28
Suggested weighting for collision severity method
29
Common methods of assessing safety at a location
30
Chi-square test values and corresponding confidence levels
31
Collision types commonly identified, possible causes, and associated treatments
32
Example calculation of safety benefit of adding a right-turn lane

 

CHAPTER 7

33
Motor vehicle LOs thresholds at signalized intersections
34
Bicycle LOs thresholds at signalized intersections
35
Pedestrian LOs thresholds at signalized intersections
36
Planning-level guidelines for sizing an intersection
37
V/C ratio threshold descriptions for the Quick Estimation Method

 

CHAPTER 8

38
Summary of issues for providing median treatments
39
Relative crash rates for unsignalized intersection access spacing
40
Summary of issues for providing access management
41
Selected findings of safety benefits associated with signal coordination or progression
42
Summary of issues for providing signal coordination
43
Summary of issues for providing signal preemption and/or priority

 

CHAPTER 9

44
Summary of issues for curb radius reduction
45
Summary of issues for curb extensions
46
Summary of issues for stop bar alterations
47
Safety benefits associated with addition of pedestrian signals: Selected findings
48
Summary of issues for pedestrian signal display improvements
49
Summary of issues for pedestrian signal phasing modifications
50
Summary of issues for pedestrian grade separation
51
Summary of issues for providing a bicycle box
52
Summary of issues for providing bicycle lanes
53
Summary of issues for near-side/far-side transit stops
54
Safety benefits associated with upgrading an intersection from pre-timed to actuated operation: Selected findings
55
Summary of issues for providing signal actuation
56
Safety benefits associated with modifying clearance intervals: Selected findings
57
Summary of issues for extending yellow/red clearance intervals
58
Summary of issues for cycle length modifications
59
Safety benefits associated with removal of signal from late night/early morning flash mode: Selected findings
60
Summary of issues for flash mode removal
61
Safety benefits associated with providing illumination: Selected findings
62
Summary of issues for providing illumination

 

CHAPTER 10

63
Summary of issues for removing intersection skew
64
Summary of issues for removing deflection of vehicle path
65
Number of conflict points at a four-leg signalized intersection compared to two closely spaced t-intersections
66
Safety benefits of converting a four-leg signalized intersection to two T-intersections: Expert opinion
67
Summary of issues for converting a four-leg intersection to two T-intersections
68
Summary of issues for converting two T-intersections to one four-leg intersection
69
Safety benefits associated with street closures: Selected findings
70
Summary of issues for closing an intersection approach leg
71
Number of conflict points at a four-leg signalized intersection compared to a four-leg signalized intersection with a jughandle
72
Safety benefits of converting a four-leg signalized intersection to a four-leg signalized intersection with two jughandles: Expert opinion
73
Summary of issues for jughandles
74
Number of conflict points at a four-leg signalized intersection compared to a four-leg signalized intersection with a median U-turn crossover configuration
75
Safety benefits of converting a four-leg signalized intersection to median U-turn crossover configuration: Expert opinion
76
Summary of issues for median U-turn crossovers
77
Number of conflict points at a four-leg signalized intersection compared to a continuous flow intersection with displaced left turns on the major street only
78
Safety benefits of converting a four-leg signalized intersection to a CFI: Expert opinion
79
Summary of issues for continuous flow intersections
80
Number of conflict points at a four-leg signalized intersection compared to a four-leg signalized intersection with a quadrant roadway
81
Safety benefits of adding a quadrant roadway to a four-leg signalized intersection: Expert opinion
82
Summary of issues for quadrant roadways
83
Number of conflict points at a four-leg signalized intersection compared to a super-street median crossover
84
Safety benefits of converting a four-leg signalized intersection compared to a super-street median crossover: Expert opinion
85
Summary of issues for super-street median crossovers
86
Number of conflict points at a four-leg signalized intersection compared to a split intersection
87
Safety benefits of converting a four-leg signalized intersection to a split intersection: Expert opinion
88
Summary of issues for split intersections
89
Number of conflict points at a four-leg signalized intersection compared to a compressed diamond and single-point diamond interchange
90
Safety benefits of converting a four-leg signalized intersection to a compressed diamond and single-point diamond interchange: Expert opinion
91
Summary of issues for single-point and compressed diamond interchanges

 

CHAPTER 11

92
Summary of approach treatments
93
Safety benefits associated with using mast arms: Selected findings
94
Summary of issues for using mast arm/span wire mounted signal heads
95
Summary of issues for supplemental near-side traffic signal heads
96
Safety benefits associated with using 300-mm (12-inch) signal lenses: Selected findings
97
Summary of issues for increasing the size of signal heads
98
Safety benefits associated with using a double red indication (red "T") display: Selected findings
99
Summary of issues for using two red signal sections
100
Safety benefits associated with addition of a signal head: Selected findings
101
Summary of issues for adding a signal head
102
Safety benefits associated with the use of signal backplates: Selected findings
103
Summary of issues for using signal head backplates
104
Safety benefits associated with advance warning signs and flashers: Selected findings
105
Summary of issues related to advance warning treatments
106
Safety benefits associated with sign treatments: Selected findings
107
Summary of issues for improving signing
108
Safety benefits associated with nonskid treatments, drainage improvements, or resurfacing: Selected findings
109
Summary of issues for pavement treatments
110
Safety benefits associated with rumble strips: Selected findings
111
Summary of issues for rumble strips
112
Summary of issues for cross section improvements
113
Summary of issues for removing obstacles from the clear zone
114
Expected reduction in number of crashes per intersection per year by increased sight distance
115
Safety benefits associated with sight distance improvements: Selected findings
116
Summary of issues for visibility improvements

 

CHAPTER 12

117
Rule-of-thumb intersection capacities assuming various exclusive left-turn treatments
118
Guidelines for use of left-turn phasing
119
Guidelines for selection of type of left-turn phasing
120
Minimum recommended sight distance for allowing permissive left turns
121
Safety benefits associated with left-turn lane design improvements: Selected findings
122
Summary of issues for left-turn lanes
123
Safety benefits associated with multiple left-turn lanes: Selected findings
124
Summary of issues for multiple left-turn lanes
125
Safety benefits associated with left-turn operational treatments: Selected finding
126
Summary of issues for turn prohibitions
127
Summary of issues for auxiliary through lanes
128
Summary of issues for path delineation
129
Right-turn lane volume warrants
130
Safety benefits associated with right-turn improvements: Selected findings
131
Summary of issues for right-turn lanes
132
Summary of issues for double right-turn lanes
133
Safety benefits associated with right-turn channelization: Selected findings
134
Summary of issues for channelized right-turn lanes
135
Summary of issues for reversible lanes
136
Summary of issues for variable lane use

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FHWA
United States Department of Transportation - Federal Highway Administration