April 2003

Roadway Lighting Design Manual

Mn/DOT Roadway Lighting Design Manual

April 2003 Page i Table of Contents

TABLE OF CONTENTS

1. INTRODUCTION....................................................................................................................1-1 1.1 Background............................................................................................................................................. 1-1 1.2 Course Schedule .................................................................................................................................... 1-1 1.3 Instructor Information.............................................................................................................................. 1-2 1.4 Acknowledgments .................................................................................................................................. 1-2 1.5 Disclaimer................................................................................................................................................ 1-3 2. LIGHTING BASICS ...............................................................................................................2-1 2.1 Definition of Terms.................................................................................................................................. 2-1 2.2 Purpose of Roadway Lighting ................................................................................................................ 2-2

2.2.1 Traffic Engineering Objectives........................................................................................................ 2-2 2.2.2 Other Objectives ............................................................................................................................. 2-2

2.3 Visibility of Objects and Lighting Quality................................................................................................ 2-2 2.3.1 Visibility............................................................................................................................................ 2-2 2.3.2 Quality.............................................................................................................................................. 2-3

2.4 Types of Lighting System Configurations.............................................................................................. 2-3 2.4.1 Continuous Freeway Lighting......................................................................................................... 2-3 2.4.2 Partial Interchange Lighting............................................................................................................ 2-3 2.4.3 Complete Interchange Lighting ...................................................................................................... 2-3 2.4.4 Underpass Lighting......................................................................................................................... 2-3 2.4.5 Lighting for Other Streets and Highways ....................................................................................... 2-3 2.4.6 Lighting on Bridges ......................................................................................................................... 2-3 2.4.7 Lighting of Roadways with Median Barriers .................................................................................. 2-4 2.4.8 Lighting at Intersections.................................................................................................................. 2-4

2.5 Lighting Warrants.................................................................................................................................... 2-4 2.5.1 Continuous Freeway Lighting......................................................................................................... 2-4 2.5.2 Complete Interchange Lighting ...................................................................................................... 2-5 2.5.3 Partial Interchange Lighting............................................................................................................ 2-5 2.5.4 Non-Freeway Lighting..................................................................................................................... 2-5

2.6 Minnesotas Energy Law ........................................................................................................................ 2-6 3. LIGHTING EQUIPMENT .......................................................................................................3-1 3.1 Lamps...................................................................................................................................................... 3-1

3.1.1 Roadway Lighting Lamp Characteristics ....................................................................................... 3-1 3.1.2 Background History of Lamps for Roadway Lighting .................................................................... 3-2 3.1.3 Mn/DOT Practice Concerning Lamps............................................................................................ 3-2

3.2 Luminaires............................................................................................................................................... 3-3 3.3 Ballasts.................................................................................................................................................... 3-6 3.4 Service Cabinets..................................................................................................................................... 3-6

3.4.1 Service Cabinet, Secondary Type L2 ............................................................................................ 3-6 3.4.2 Service Cabinet, Secondary Type L1 ............................................................................................ 3-7 3.4.3 Service Cabinet, Secondary Type A.............................................................................................. 3-7 3.4.4 Service Cabinet, Secondary Type B.............................................................................................. 3-8

3.5 Poles........................................................................................................................................................ 3-8 3.5.1 General Information ........................................................................................................................ 3-8 3.5.2 Breakaway Pole Issues .................................................................................................................. 3-9 3.5.3 Placement Issues............................................................................................................................ 3-9 3.5.4 Pole Designations ......................................................................................................................... 3-10 3.5.5 Mn/DOT Standard Pole Equipment ............................................................................................. 3-12

3.6 Light Bases (Foundations) ................................................................................................................... 3-13 3.7 Equipment Pads ................................................................................................................................... 3-13 3.8 Selecting the Lighting Systems............................................................................................................ 3-14

3.8.1 Cobra Head Lighting Systems...................................................................................................... 3-14

Mn/DOT Roadway Lighting Design Manual

April 2003 Page ii Table of Contents

3.8.2 Vertical Mount Lighting Systems.................................................................................................. 3-14 3.8.3 High Mast Lighting Systems......................................................................................................... 3-14 3.8.4 Shoebox or Round Lighting Options............................................................................................ 3-15

4. PHOTOMETRY......................................................................................................................4-1 4.1 Photometrics ........................................................................................................................................... 4-1

4.1.1 Coefficient of utilization ................................................................................................................... 4-1 4.1.2 Isofootcandle chart.......................................................................................................................... 4-2 4.1.3 Vertical Light Distributions .............................................................................................................. 4-3 4.1.4 Lateral Light Distributions ............................................................................................................... 4-4

4.2 Lamp and Luminaire Depreciation Factors ........................................................................................... 4-5 5. LIGHTING DESIGN ...............................................................................................................5-1 5.1 Lighting Design ....................................................................................................................................... 5-1 5.2 Mn/DOT Roadway Lighting Design Process......................................................................................... 5-1

5.2.1 Lighting Design Checklist ............................................................................................................... 5-2 5.2.2 L