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FHWA Home / Safety / Intersection / Signalized Intersections: An Informational Guide

Signalized Intersections: An Informational Guide

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FHWA Office of Safety logo: Safe Roads for a Safer Future – Investment in roadway safety saves lives.

Federal Highway Administration
Office of Safety

July 2013

FHWA-SA-13-027

For more information, contact:
Jeffrey Shaw
jeffrey.shaw@dot.gov
708-283-3524

http://safety.fhwa.dot.gov/intersection




Foreword

This report, now in its Second Edition, complements the American Association of State Highway and Transportation Officials (AASHTO) Strategic Highway Safety Plan (SHSP) efforts to develop guidance on enhancing the safety of unsignalized and signalized intersections. The overarching goal is to reduce the number of traffic related deaths that occur on highways and streets in the United States. This guide is an introductory 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 or signing and markings, to high-cost measures such as intersection widening or reconstruction. Topics covered include fundamental principles of user needs and human factors, multimodal accommodations (emphasizing pedestrians and bicyclists), elements of geometric design, and traffic safety design and operation; safety, maintenance and operations practices; and a wide variety of treatments, techniques and strategies to address existing or anticipated problems at multiple levels, including corridor, approach and individual movement treatments. Each recommended treatment includes a discussion of safety performance, operations, multimodal issues, and physical and economic factors that the practitioner should consider. While some treatments may be better suited to high-volume intersections, most of the treatments are applicable for lower volume intersections and would be worthy of systemic implementation. Every attempt has been made to reflect the latest research and documentation on available treatments and best practices in use by jurisdictions across the United States at the time of publication. Since the scope of this guide is necessarily limited, additional resources and references are highlighted for the student, practitioner, researcher, or decision maker who endeavors to learn more about a particular subject.

An electronic version of this document can be downloaded from the Federal Highway Administration, Office of Safety website at http://safety.fhwa.dot.gov/. A hard copy may be requested by contacting the National Highway Institute, 1310 North Courthouse Road, Suite 300, Arlington, VA 22201; telephone (703) 235-0500; fax (703) 235-0593.

Michael Griffith signature.
Michael Griffith
Director
Office of Safety Technologies

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.




Table of Contents

Technical Report Documentation Page [ PDF, HTML ]
List of Acronyms [ PDF, HTML ]
Glossary of Terms [ PDF, HTML ]
SI Conversion Factors [ PDF, HTML ]
 
1. INTRODUCTION [ PDF, HTML ]
  1.1 Background
  1.2 Performance Measurement and Asset Management
  1.3 Scope of the Guide
  1.4 Audience for this Guide
  1.5 Organization of the Guide
 
PART I: FUNDAMENTALS [ PDF, HTML ]
 
2 HUMAN FACTORS [ PDF, HTML ]
  2.1 Overview of Human Factors
  2.2 Intersection Users
  2.3 Applying Human Factors
3 DATA COLLECTION AND WARRANTS [ PDF, HTML ]
  3.1 Commitment
  3.2 Where Do You Start? Importance of an Engineering Analysis and Study
  3.3 Intersection Data Collection Needed
  3.4 Intersection Counts
  3.5 Traffic Signal Warrants
  3.6 When is Not Signalizing an Intersection the Right Decision?
4 GEOMETRIC DESIGN [ PDF, HTML ]
  4.1 Number of Intersection Legs
  4.2 Channelization
  4.3 Horizontal and Vertical Alignment
  4.4 Corner Radius
  4.5 Sight Distance
  4.6 Pedestrian Treatments
  4.7 Bicycle Facilities
  4.8 Transit Facilities
5 TRAFFIC DESIGN AND ILLUMINATION [ PDF, HTML ]
  5.1 Traffic Signal Phasing
  5.2 Vehicle and Pedestrian Displays
  5.3 Traffic Signal Pole Layout
  5.4 Traffic Signal Controller and Cabinet
  5.5 Detection Devices
  5.6 Traffic Signal Control Type
  5.7 Basic Signal Timing Parameters
  5.8 Signing and Pavement Marking Design
  5.9 Illumination Design
 
PART II: PROJECT PROCESS ANALYSIS METHODS [ PDF, HTML]
 
6 SAFETY ANALYSIS METHODS [ PDF, HTML ]
  6.1 Qualitative Approach
  6.2 Quantitative Approach
  6.3 Network Screening or Selection of an Intersection
  6.4 Diagnosis
  6.5 Selecting Countermeasures
  6.6 Economic Appraisal
  6.7 Project Prioritization
  6.8 Safety Effectiveness Evaluation
7 OPERATIONAL ANALYSIS METHODS [ PDF, HTML ]
  7.1 Operational Performance Measures
  7.2 Traffic Operations Elements
  7.3 General Considerations Sizing an Intersection
  7.4 Critical Lane Analysis
  7.5 HCM Operational Procedure for Signalized Intersections
  7.6 Arterial and Network Signal Timing Models
  7.7 Microscopic Simulation Models
  7.8 Operational Performance Model Selection
 

PART III: TREATMENTS [ PDF, HTML ]

 
8 SYSTEM-WIDE TREATMENTS [ PDF, HTML ]
  8.1 Median Treatments
  8.2 Access Management
  8.3 Signal Coordination
  8.4 Signal Preemption and/or Priority
9 INTERSECTION-WIDE TREATMENTS [ PDF, HTML ]
  9.1 Pedestrian Treatments
  9.2 Bicycle Treatments
  9.3 Transit Treatments
  9.4 Traffic Control Treatments
  9.5 Street Lighting and Illumination
  9.6 Remove Traffic Signal
10 APPROACH TREATMENTS [ PDF, HTML ]
  10.1 Signal Head Placement and Visibility
  10.2 Signing and Speed Control Treatments
  10.3 Roadway Surface Improvements
  10.4 Sight Distance Treatments
  10.5 Dilemma Zone Detection
  10.6 Red Light Camera Enforcement
11 INDIVIDUAL MOVEMENT TREATMENTS [ PDF, HTML ]
  11.1 Left-Turn Treatments
  11.2 Right-Turn Treatments
  11.3 Variable Lane Use Treatments
References [ PDF, HTML ]
Page last modified on September 4, 2014.
Safe Roads for a Safer Future - Investment in roadway safety saves lives
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000