Traffic Signal Design Guidelines

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TRAFFIC SIGNAL DESIGN GUIDELINES

Revision: 2.0
September 2010

Document Revision History

DATE| REV.| SPCR(s)| SECTIONS| DESCRIPTION|
11/2000| Rev. 1| | | Initial release of document|
05/2003| Rev. 1.1| | | Draft of first major update|
11/2003| Rev. 1.2| | | Final of first major update|
7/2010| Rev. 2.0| | | Major update|

GEORGIA DEPARTMENT OF TRANSPORTATION
TRAFFIC SIGNAL DESIGN GUIDELINES

TABLE OF CONTENTS
Section 11
INTRODUCTION1
1.1Applicable Standards and Specifications1
Section 21
GENERAL INFORMATION1
2.1General Signal Plan Presentation1
2.2List of Materials/Pay Items2
2.3Miscellaneous Elements and Special Situations2
Section 31
DESIGN STANDARDS1
3.1Traffic Signal (Concurrent) Phasing1
3.1.1 Left-Turn Phasing2
3.1.2 Split Phasing2
3.1.3Preemption3
3.1.3.1 Railroad Preemption3
3.1.3.2 Blank-Out Signs4
3.1.3.3 Emergency Vehicle Preemption6
3.2Vehicular Signals6
3.2.1 Display7
3.2.2 Mounting7
3.2.3 Position7
3.2.3.1 Head Placement Guidelines7
3.2.3.2 Guidelines for Channelized Left-Turn Lanes with Wide Medians8 3.2.4Signal Head Equipment10
3.3Pedestrian Signals and Poles10
3.3.1Pedestrian Considerations10
3.3.2Pedestrian Signal Heads11
3.3.3Curb Ramps11
3.3.4 Pedestrian Refuge Islands11
3.3.5 Poles12
3.3.6 Signs12
3.4 Traffic Signal Poles14
3.4.1Pole Placement14
3.4.2Strain Poles14
3.4.3Timber Poles14
3.4.4 Joint Use Poles15
3.5Span Wire Configurations15
3.6Mast Arm Configurations15
3.7Cabinet Assemblies16
3.7.1 Controller Equipment and Software16
3.7. 2Cabinet and Cabinet Bases16
3.7.2.1 Input File17
3.7.3 Battery Backup (Definitions and Reasons Why)18
3.7.4Modems18
3.7.5Cabinet Placement20
3.7.6Power Disconnect20
3.8Vehicle Detection21
3.8.1 Detector Modes21
3.8.1.1 Presence Detectors21
3.8.1.2Pulse Detectors (Volume Density/Setback Detectors)22 3.8.1.3Call Detection22
3.8.1.4Queue Detection23
3.8.2 Methods of Detection23
3.8.2.1 Inductive Loop Detectors23
3.8.2.2 Intersection Video Detection System (IVDS)24
3.9Communication/Interconnect25
3.10Wiring, Conduit and Pull Boxes28
3.10.1Wiring Standards28
3.10.2Conduits and Pull Boxes28
3.11Traffic-Signal-Related Signs and Pavement Markings30
3.11.1Signs30
3.11.1.1 Post-Mounted Signs30
3.11.1.2 Overhead Street Name Signs30
3.11.2Pavement Markings32
Appendix A
Example Plan Set1
Appendix B
Vehicular Signal Head Placement Examples2

LIST OF FIGURES

FIGURE 3-1 Phasing Orientation3-1
FIGURE 3-2 Split Phasing Orientation……………………………………………………………………………....3-3 FIGURE 3-3 Blank-Out Sign Displays………………………………………………………………………………3-5 FIGURE 3-4 Sample Preemption Phasing Diagram…………………………………………………………………3-5

FIGURE 3-5 Signal Head/Left-Turn Treatment3-8
FIGURE 3-6 Left-Turn Lane Signal Head Alignment3-9
FIGURE 3-7 Typical Pedestrian Treatment at Right-Turn Islands3-12
FIGURE 3-8 Pedestrian Crossings3-13

LIST OF TABLES

Table 3-1 332A Cabinet Input Assignment3-19
Table 3-2 336S Cabinet Input Assignment3-19
Table 3-3 Setback Detector Placement3-22

Section 1
INTRODUCTION

The purpose of these design guidelines is to document standards, procedures and specifications that should be used for the design of traffic signal installations and signal system communications for the Georgia Department of Transportation (GDOT). These design guidelines include a compilation of specific drafting and intersection design standards, plan and specification presentations, and review procedures to ensure that construction documents properly convey the extent and character of the work to be performed. Sound traffic engineering judgment should be exercised in applying these guidelines. Along with the companion document on signing and marking design, this document contains comprehensive guidelines...
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