DISPLACED LEFT TURN

INTERSECTION

Informational Guide 

August 2014 
FOREWORD

The Federal Highway Administration (FHWA) Every Day Counts (EDC) initiative is designed to 

identify and deploy innovation aimed at reducing project delivery time, enhancing safety and 

protecting the environment. In 2012, FHWA chose Intersection & Interchange Geometrics (IIG) 

to feature as one of the innovative technologies in EDC-2. Specifically, IIG consists of a family 

of alternative intersection designs that improve intersection safety while also reducing delay, and 

at lower cost and with fewer impacts than comparable traditional solutions.

As part of the effort to mainstream these intersections, FHWA has produced a series of guides to 

help transportation professionals routinely consider and implement these designs. Concurrent 

with this Displaced Left Turn (DLT) Informational Guide, FHWA developed and published 

guides for three other designs: Median U-turn (MUT), Restricted Crossing U-turn (RCUT), and 

Diverging Diamond Interchange (DDI). These guides represent summaries of the current state of 

knowledge and practice, and are intended to inform project planning, scoping, design and 

implementation decisions.

An electronic version of this document is available on the Office of Safety website at 

http://safety.fhwa.dot.gov/. Additionally, limited quantities of hard copies are available from the 

Report Center; inquiries may be directed to report.center@dot.gov or 814-239-1160. 

Michael S. 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. This report does not constitute a standard, 

specification, or regulation. 

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. 
i 

Technical Report Documentation Page

1. Report No.

FHWA-SA-14-068

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Displaced Left Turn Informational Guide

5. Report Date

August 2014

6. Performing Organization Code

7. Authors

Hermanus Steyn, Zachary Bugg, Brian Ray, Andy Daleiden, Pete Jenior, Julia 

Knudsen, Kittelson & Associates, Inc. Project 13517

8. Performing Organization Report No.

9. Performing Organization Name and Address

Kittelson & Associates, Inc.

610 SW Alder Street, Suite 700 

Portland, OR 97205

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

TO DTFH61-00023-T-13002

12. Sponsoring Agency Name and Address

U.S. Department of Transportation

Federal Highway Administration Office of Safety 

1200 New Jersey Ave., SE

Washington, DC 20590

13. Type of Report and Period 

Technical Report

Informational Report

September 2013 to August 2014

14. Sponsoring Agency Code

FHWA

15. Supplementary Notes

Jeffrey Shaw (jeffrey.shaw@dot.gov), Office of Safety Technologies (http://safety.fhwa.dot.gov/), served as the Technical

Manager for the Federal Highway Administration (FHWA). The following FHWA staff contributed as technical working group 

members, reviewers and/or provided input or feedback to the project at various stages: Joe Bared, Mark Doctor, Brian Fouch, 

Elizabeth Hilton, Jim McCarthy, George Merritt, Will Stein, Jim Sturrock and Wei Zhang.

16. Abstract

This document provides information and guidance on the Displaced Left Turn (DLT) intersection. To the extent possible, the 

guide addresses a variety of conditions found in the United States, to achieve designs suitable for a wide array of potential users. 

This guide provides general information, planning techniques, evaluation procedures for assessing safety and operational 

performance, design guidelines, and principles to be considered for selecting and designing DLT intersections. 

17. Key Words

DLT, CFI, Displaced left turn, Continuous flow intersection, Alternative 

intersections, Alternative interchanges, Innovative Intersections

18. Distribution Statement

No restrictions. 

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

152

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized
Displaced Left Turn Informational Guide

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Displaced Left Turn Informational Guide

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TABLE OF CONTENTS

CHAPTER 1— INTRODUCTION ............................................................................................. 1

OVERVIEW OF ALTERNATIVE INTERSECTIONS AND INTERCHANGES ................... 1

INTERSECTION CONTROL EVALUATIONS AND CONSIDERATIONS ......................... 1

ORGANIZATION OF THE GUIDELINES .............................................................................. 2

SCOPE OF THE GUIDE ............................................................................................................ 3

DLT INTERSECTION OVERVIEW ......................................................................................... 3

APPLICATION ......................................................................................................................... 4

GEOMETRIC DESIGN CONSIDERATIONS ........................................................................ 10

RESOURCE DOCUMENTS .................................................................................................... 12

CHAPTER 2— POLICY AND PLANNING ........................................................................... 15

PLANNING CONSIDERATIONS FOR ALTERNATIVE INTERSECTIONS AND 

INTERCHANGES .................................................................................................................... 15

STAKEHOLDER OUTREACH ............................................................................................... 19

POLICY CONSIDERATIONS ................................................................................................ 21

PLANNING CONSIDERATIONS .......................................................................................... 22

PLANNING CHALLENGES ................................................................................................... 23

PROJECT PERFORMANCE CONSIDERATIONS ............................................................... 24

PROJECT DEVELOPMENT PROCESS ................................................................................. 25

SUMMARY OF DLT ADVANTAGES AND DISADVANTAGES ...................................... 26

CHAPTER 3— MULTIMODAL CONSIDERATIONS ......................................................... 29

DESIGN PRINCIPLES AND APPROACH ............................................................................ 29

PEDESTRIANS ....................................................................................................................... 29

BICYCLISTS ............................................................................................................................ 37

TRANSIT VEHICLE CONSIDERATION .............................................................................. 41

HEAVY VEHICLE CONSIDERATIONS ............................................................................... 44

CHAPTER 4— SAFETY ........................................................................................................... 45

SAFETY PRINCIPLES ............................................................................................................ 45

OBSERVED SAFETY PERFORMANCE ............................................................................... 48

SAFETY CONSIDERATIONS ................................................................................................ 49

INCIDENT RESPONSE CONSIDERATIONS ....................................................................... 51

SAFETY EVALUATION CONSIDERATIONS ..................................................................... 52

CHAPTER 5— OPERATIONAL CHARACTERISTICS ..................................................... 53

OPERATIONAL PRINCIPLES ............................................................................................... 53

OPERATIONAL CONSIDERATIONS ................................................................................... 59
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COMPARATIVE PERFORMANCE STUDIES ...................................................................... 61

CHAPTER 6— OPERATIONAL ANALYSIS ........................................................................ 65

OPERATIONAL ANALYSIS TOOL OVERVIEW ................................................................ 66

PLANNING LEVEL ANALYSIS ............................................................................................ 67

HIGHWAY CAPACITY MANUAL (HCM) ANALYSIS ...................................................... 69

MICROSIMULATION ANALYSIS ........................................................................................ 70

CHAPTER 7— GEOMETRIC DESIGN ................................................................................. 71

DESIGN APPROACH.............................................................................................................. 71

GEOMETRIC DESIGN PARAMETERS/PRINCIPLES......................................................... 72

RANGE OF DLT INTERSECTION CONFIGURATIONS .................................................... 76

OPERATIONAL EFFECTS OF GEOMETRIC DESIGN ....................................................... 80

DESIGN GUIDANCE .............................................................................................................. 82

CHAPTER 8— SIGNAL, SIGNING, MARKING, AND LIGHTING .................................. 91

DESIGN PRINCIPLES AND APPROACH ............................................................................ 91

SIGNALS .................................................................................................................................. 91

SIGNING .................................................................................................................................. 96

PAVEMENT MARKINGS ...................................................................................................... 99

LIGHTING ............................................................................................................................. 101

CHAPTER 9— CONSTRUCTION AND MAINTENANCE ............................................... 103

CONSTRUCTION .................................................................................................................. 103

MAINTENANCE ................................................................................................................... 107

LAW ENFORCEMENT NEEDS ........................................................................................... 108

REFERENCES ...................................................................................................................... 109

Appendix A CATALOG OF ALL KNOWN INSTALLATIONS IN THE UNITED 

STATES ....................................................................................................... 113

Appendix B SUPPLEMENTAL OPERATIONAL AND SAFETY DETAILS .......... 117

Appendix C MARKETING AND OUTREACH MATERIALS .................................. 129

Appendix D SUPPLEMENTAL CONSTRUCTION AND DESIGN DETAILS ....... 135
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List of Exhibits

Exhibit 1-1. Four-legged DLT with displaced lefts on a major street. ........................................... 4

Exhibit 1-2. Locations of DLT intersections. ................................................................................. 5

Exhibit 1-3. Four-legged DLT intersection with four displaced lefts (West Valley City, UT).(1) .. 5

Exhibit 1-4. Four-legged DLT intersection with major street displaced lefts and channelized right 

turns (Baton Rouge, LA).(1) ............................................................................................................ 6

Exhibit 1-5. Three-legged DLT intersection with major street displaced left and channelized right 

turns (Shirley, NY).(1) ..................................................................................................................... 7

Exhibit 1-6. Example of a bus stop and bus only lane at the Bangerter Highway/3500 South 

Intersection in Utah.(2) ..................................................................................................................... 7

Exhibit 1-7. Crossover intersection at the Bangerter Highway/3100 South Intersection in Utah.(2)

......................................................................................................................................................... 8

Exhibit 1-8. Left-turn lane at the main intersection of the Bangerter Highway/3100 South 

Intersection in Utah.(2) ..................................................................................................................... 8

Exhibit 1-9. Main intersection at Bangerter Highway/3100 South Intersection in Utah.(2) ............ 9

Exhibit 1-10. Lighting, pedestrian signage, and video detection at the right-turn channelization at 

the Bangerter Highway/3500 South Intersection in Utah.(2) ........................................................... 9

Exhibit 1-11. Bicyclist crossing with through vehicles at the Bangerter Highway/3500 South 

Intersection in Utah.(2) ................................................................................................................... 10

Exhibit 1-12. DLT intersection with displaced left turns on all approaches. ............................... 11

Exhibit 1-13. Three-legged DLT intersection with displaced left turns on major road approach. 12

Exhibit 1-14. DLT without channelized right turns. ..................................................................... 12

Exhibit 2-1. Relationship between total entering volume and intersection type. ......................... 17

Exhibit 2-2. Footprint comparison of a DLT intersection with tangent alignments versus a 

conventional intersection. ............................................................................................................. 18

Exhibit 2-3. Footprint comparison of a DLT intersection with deflected through alignments 

versus a conventional intersection. ............................................................................................... 19

Exhibit 2-4. CFI (DLT intersection) instruction card for UDOT.(12) ............................................ 20

Exhibit 2-5. Project development process. ................................................................................... 25

Exhibit 2-6. Summary of DLT advantages and disadvantages. .................................................... 27

Exhibit 3-1. DLT in Dayton, OH with two-stage crossings of main line.(1) ................................. 30

Exhibit 3-2. Possible pedestrian movements with one-stage crossings of main line at a DLT 

intersection. ................................................................................................................................... 31

Exhibit 3-3. Channelized right-turn design.(22) ............................................................................. 32

Exhibit 3-4. Refuge islands between left-turn and through lanes. ................................................ 33

Exhibit 3-5. Pedestrian-vehicle conflict point diagram for a DLT intersection with two displaced 

left turns with a single-stage crossing. .......................................................................................... 34

Exhibit 3-6. Pedestrian-vehicle conflict point diagram for a DLT intersection with four displaced 

left turns with a single-stage crossing. .......................................................................................... 34

Exhibit 3-7. Pedestrian-vehicle conflict point diagram for a DLT intersection with two displaced 

left turns with a two-stage crossing. ............................................................................................. 35

Exhibit 3-8. Pedestrian-vehicle conflict point diagram for a DLT intersection with four displaced 

left turns with a two-stage crossing. ............................................................................................. 35

Exhibit 3-9. Pedestrian-vehicle conflict point diagram for a conventional intersection............... 36

Exhibit 3-10. Accommodating on-street bicycles through a DLT intersection. ........................... 38

Exhibit 3-11. Accommodating off-street bicycles through a DLT intersection. .......................... 39
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Exhibit 3-12. Accommodating on-street left-turning bicycles with a bicycle box through a DLT 

intersection. ................................................................................................................................... 40

Exhibit 3-13. Accommodating off-street left-turning bicycles through a DLT intersection. ....... 40

Exhibit 3-14. Potential transit midblock stop location in a DLT intersection. ............................. 42

Exhibit 3-15. Potential nearside stop locations with pullouts. ...................................................... 43

Exhibit 3-16. Potential stop locations in travel lanes. ................................................................... 44

Exhibit 4-1. Conflict point comparison. ....................................................................................... 46

Exhibit 4-2. Conflict point diagram for a conventional intersection. ........................................... 46

Exhibit 4-3. Conflict point diagram for a DLT intersection with two displaced left turns. .......... 47

Exhibit 4-4. Conflict point diagram for a DLT intersection with four displaced left turns. ......... 47

Exhibit 4-5. Dowling College DLT intersection in Shirley, NY.(1) .............................................. 48

Exhibit 4-6. Undesirable crossover intersection layout. ............................................................... 50

Exhibit 4-7. Desirable crossover intersection layout. ................................................................... 50

Exhibit 4-8. Emergency preemption movements on one approach of a DLT intersection........... 52

Exhibit 5-1. Concurrent movements for east-west arterial at conventional intersection and DLT 

intersection. ................................................................................................................................... 54

Exhibit 5-2. Typical DLT intersection signal locations. ............................................................... 55

Exhibit 5-3. Two-phase signal phasing at five separately controlled signalized intersections 

within a DLT intersection. ............................................................................................................ 56

Exhibit 5-4. Signal phasing for a DLT intersection with a single controller. ............................... 57

Exhibit 5-5. Signal phasing for a DLT intersection with major street displaced left turns with a 

single phase crossing for pedestrians. ........................................................................................... 58

Exhibit 5-6. Typical signal coordination. ..................................................................................... 59

Exhibit 5-7. Location of U-turn, frontage road, and driveway at DLT intersection in Baton 

Rouge, LA.(1) ................................................................................................................................. 60

Exhibit 5-8. Bangerter Highway Corridor in Utah.(12) .................................................................. 61

Exhibit 5-9. Comparative simulation results.(25) ........................................................................... 63

Exhibit 6-1. DLT analysis techniques. .......................................................................................... 67

Exhibit 6-2. CAP-X Planning Level Tool Screen Capture.(31)...................................................... 68

Exhibit 7-1. DLT characteristics. .................................................................................................. 72

Exhibit 7-2. Left-turn maneuvers. ................................................................................................. 73

Exhibit 7-3. Crossover intersection geometry. ............................................................................. 74

Exhibit 7-4. Add lane with a downstream lane merge. ................................................................. 75

Exhibit 7-5. Signalized right turn.................................................................................................. 75

Exhibit 7-6. Four-legged DLT intersection with four displaced left turns and without channelized 

right turns (West Valley City, UT).(1) ........................................................................................... 77

Exhibit 7-7. Four-legged DLT intersection with major street displaced left turns and without 

channelized right turns (West Valley City, UT).(1) ....................................................................... 78

Exhibit 7-8. Four-legged DLT intersection with major street displaced left turns and channelized 

right turns (Baton Rouge, LA).(1) .................................................................................................. 79

Exhibit 7-9. Three-legged DLT intersection with major street displaced left turn (Shirley, NY).(1)

....................................................................................................................................................... 79

Exhibit 7-10. Three-legged DLT intersection with minor street displaced left turn (Accokeek, 

MD). (1) .......................................................................................................................................... 80

Exhibit 7-11. Types of channelized turns.(22) ................................................................................ 81
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Exhibit 7-12. Footprint comparison of a DLT intersection with tangent through alignments 

versus a conventional intersection. ............................................................................................... 83

Exhibit 7-13. Footprint comparison of a DLT intersection with deflected through alignments 

versus a conventional intersection. ............................................................................................... 84

Exhibit 7-14. Side-by-side maneuvers at crossover intersection. ................................................. 86

Exhibit 7-15. Semi-truck maneuvers at crossover intersection. ................................................... 86

Exhibit 7-16. Side-by-side left turns at main intersection. ........................................................... 87

Exhibit 7-17. Semi-truck maneuver at main intersection. ............................................................ 88

Exhibit 7-18. Typical intersection spacing. .................................................................................. 89

Exhibit 7-19. Bicycle box for left turn. ......................................................................................... 90

Exhibit 8-1. Possible signal pole and mast arm locations for a DLT intersection. ....................... 92

Exhibit 8-2. Possible detector placement locations for a DLT intersection with five separate 

controllers. .................................................................................................................................... 94

Exhibit 8-3. Possible detector placement locations for a DLT intersection with a single 

controller. ...................................................................................................................................... 95

Exhibit 8-4. Angular arrow signal display. ................................................................................... 95

Exhibit 8-5. Progression of overhead signs for the DLT crossover intersection.(33) ..................... 96

Exhibit 8-6. Example guide signing along an intersection approach for a DLT intersection. ...... 97

Exhibit 8-7. Regulatory and warning signs................................................................................... 98

Exhibit 8-8. High treatment on minor street approach.(33) ............................................................ 99

Exhibit 8-9. Pavement markings along an intersection approach for a DLT intersection. ......... 100

Exhibit 9-1. Phase I construction. ............................................................................................... 104

Exhibit 9-2. Phase II construction. .............................................................................................. 105

Exhibit 9-3. Phase III construction. ............................................................................................ 106

Exhibit 9-4. Summary of costs associated with DLT intersections. ........................................... 107
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CHAPTER 1— INTRODUCTION

OVERVIEW OF ALTERNATIVE INTERSECTIONS AND INTERCHANGES

Alternative intersections and interchanges offer the potential to improve safety and reduce delay 

at a lower cost and with fewer impacts than traditional solutions. However, transportation 

professionals are generally unfamiliar with many alternative intersection and interchange forms, 

partially because some forms have only a few installations in operation or because installations 

are concentrated in a few states. Furthermore, at the national level, well-documented and 

substantive resources needed for planning, analysis, design, and public outreach and education 

were limited. 

Concurrent with this Displaced Left Turn (DLT) Informational Guide, the Federal Highway 

Administration (FHWA) developed and published informational guides for three other 

alternative intersection and interchange forms: Median U-Turn (MUT), Restricted Crossing UTurn (RCUT), and Diverging Diamond Interchange (DDI). These guides are intended to increase 

awareness of these specific alternative intersections and interchanges and provide guidance on 

how to plan, design, construct, and operate them. The guides represent summaries of the current 

state of knowledge with the intent of supporting decisions when considering and potentially 

selecting alternative intersection and interchange forms for appropriate applications.

INTERSECTION CONTROL EVALUATIONS AND CONSIDERATIONS

The term “intersection” means the junction of two or more streets. In some cases, this may 

specifically mean an “at-grade” intersection form. In others, it may include the junction of two or 

more streets requiring partial or complete grade separation (“interchanges”). A number of state 

and city transporation agencies have or are implementing intersection control evaluation 

processes or policies as a means of integrating the widest range of intersection forms as project 

solutions. For example, California, Indiana, Minnesota, and Wisconsin have policies or processes 

to objectively consider and select the most appropriate intersection form for a given project 

context. 

Many of the policies or processes include common objectives in selecting the optimal or 

preferred intersection control alternative for a given project context. The common elements 

generally include but are not limited to the following:

• Understanding the intended context, and how operations, safety, and geometry fit the 

context for each intersection or corridor including intended users (pedestrians, bicyclists, 

passenger cars, transit vehicles, freight, emergency responders, and over size/over weight 

[OSOW] vehicles)

• Identifying and documenting the overall corridor or intersection context including the 

built, natural, and community environment and the intended performance outcomes of the 

intersection form 

• Considering and assessing a wide range of traffic control strategies and other practical 

improvement concepts to identify worthy project-level technical evaluation
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• Comparing engineering and economic analysis results of practical alternatives that 

consider implementation costs, performance benefits and impacts (safety, multimodal, 

operations, environment, etc.), and the estimated service life of alternatives 

ORGANIZATION OF THE GUIDELINES

This guide has been structured to address the needs of a variety of readers, including the general 

public, policy makers, transportation planners, operations and safety analysts, and conceptual 

and detailed designers. This chapter distinguishes DLT intersections from conventional 

intersections and provides an overview of each chapter in this guide. The remaining chapters in 

this guide increase in the level of detail provided. 

Chapter 2: Policy and Planning—This chapter provides guidance on when to consider 

alternative intersections in general and DLT intersections in particular. The transportation 

professional should consider policies, project challenges, performance measures, and the project 

development process throughout the duration of the project to balance trade-offs.

Chapter 3: Multimodal Considerations—This chapter provides an overview of multimodal 

facilities at DLT intersections and how the needs of various users should inform decisions to 

produce an intersection that optimally serves non-motorized and motorized traffic. 

Chapter 4: Safety—This chapter summarizes documented safety performance and safety 

considerations at DLT intersections based on studies completed by state agencies and recent 

research efforts. Although the documented safety performance of DLT intersections is limited,

information about conflict points, wrong-way maneuvers, and emergency services at the DLT are 

discussed. 

Chapter 5: Operational Characteristics—This chapter provides information on the unique 

operational characteristics of DLT intersections and how they affect elements such as traffic 

signal phasing and coordination. The chapter also provides guidance for practitioners related to 

design elements such as driveways that may affect the operational performance of DLT 

intersections. It is intended to help readers understand the unique operational characteristics of 

DLT intersections and prepare readers for conducting operational analysis as described in 

Chapter 6. 

Chapter 6: Operational Analysis—This chapter presents an overview of the approach and tools 

available for conducting a traffic operations analysis of a DLT intersection. 

Chapter 7: Geometric Design—This chapter describes the typical DLT intersection design 

approach and provides guidance for geometric features. Design of a DLT intersection will also 

require review of the intersection’s multimodal considerations (Chapter 3), safety assessment 

(Chapter 4), and traffic operational analysis (Chapters 5 and 6). 

Chapter 8: Signal, Signing, Marking, and Lighting—This chapter presents information 

relating to the design and placement of traffic control devices at DLT intersections, including 

traffic signals, signs, and pavement markings, as well as intersection lighting. 
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Chapter 9: Construction and Maintenance—This chapter focuses on the constructability and 

maintenance of a DLT intersection. 

An Appendix is included at the end of this guide for the purpose of providing more detailed 

information about many of the resources and best practices presented in the guide. The Appendix 

contains the following information: 

• A - Catalog of All Known Installations in the United States

• B - Supplemental Operational and Safety Details

• C - Marketing and Outreach Materials

• D - Supplemental Construction and Design Details 

SCOPE OF THE GUIDE

This document provides information and guidance on planning and designing DLT intersections 

for a variety of typical conditions commonly found in the United States. To the extent possible, 

the guide provides information on the wide array of potential users as it relates to the intersection 

form. The scope of this guide is to provide general information, planning techniques, evaluation 

procedures for assessing safety and operational performance, design guidelines, and principles to 

be considered for selecting and designing DLT intersections. This guide does not include specific 

legal or policy requirements; however, Chapter 2 provides information on planning topics and 

considerations when investigating intersection control forms. This first edition of the Displaced 

Left Turn Informational Guide has been developed from best practices and prior research. As 

more DLT intersections are built, the opportunity to conduct research that refines and develops 

better methods will result in improved future editions of this guide. 

DLT INTERSECTION OVERVIEW

The displaced left turn (DLT) intersection is also known as a continuous flow intersection (CFI) 

and a crossover displaced left-turn intersection. For the purpose of this informational guide, DLT 

refers to any intersection form relocating one or more left-turn movements on an approach to the 

other side of the opposing traffic flow. This attribute consequently allows left-turn movements to 

proceed simultaneously with the through movements and eliminates the left-turn phase for this 

approach. The number of traffic signal phases and conflict points (locations where user paths 

cross) are reduced at a DLT intersection, which can result in improvements in traffic operations 

and safety performance. The green time formerly allocated for the left turn at a conventional 

intersection could be reallocated, including being used to facilitate pedestrian crossings. 

As shown in Exhibit 1-1, traffic that would normally turn left at the main intersection would first 

cross the opposing through lanes at a signal-controlled intersection several hundred feet upstream 

of the main intersection. Left-turning vehicles then would travel on a new street parallel to the 

opposing lanes and execute the left-turn maneuver simultaneously with the through traffic at the 

main intersection. Traffic signals, operating in a coordinated manner, are present at the main 

intersection and the locations of the left-turn crossovers. 
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Exhibit 1-1. Four-legged DLT with displaced lefts on a major street. 

Exhibit 1-1 shows a DLT intersection where the displaced left-turn movement has been 

implemented on two legs on the major street. In some cases, the displaced left turns are on the 

minor street instead of the major street. The left-turn movements for the minor road continue to 

take place at the main intersection. There are five junctions with traffic signal control at a fourleg DLT intersection: the main intersection and the four left-turn crossover intersections. 

APPLICATION

Several DLT intersections have been installed throughout the United States, and each location is 

documented in the Appendix. Exhibit 1-2 shows the location of existing DLT intersections in the 

United States, as of the publication of this guide. 
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Exhibit 1-2. Locations of DLT intersections.

Exhibit 1-3 through Exhibit 1-11 feature photos of DLT intersections illustrating different 

contextual environments and a variety of design features. 

Exhibit 1-3. Four-legged DLT intersection with four displaced lefts (West Valley City, 

UT).

(1) 
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Exhibit 1-4. Four-legged DLT intersection with major street displaced lefts and 

channelized right turns (Baton Rouge, LA).

(1)
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Exhibit 1-5. Three-legged DLT intersection with major street displaced left and 

channelized right turns (Shirley, NY).

(1)

Exhibit 1-6. Example of a bus stop and bus only lane at the Bangerter Highway/3500 South 

Intersection in Utah.

(2)
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Exhibit 1-7. Crossover intersection at the Bangerter Highway/3100 South Intersection in 

Utah.

(2)

Exhibit 1-8. Left-turn lane at the main intersection of the Bangerter Highway/3100 South 

Intersection in Utah.

(2)
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Exhibit 1-9. Main intersection at Bangerter Highway/3100 South Intersection in Utah.(2)

Exhibit 1-10. Lighting, pedestrian signage, and video detection at the right-turn 

channelization at the Bangerter Highway/3500 South Intersection in Utah.(2)
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Exhibit 1-11. Bicyclist crossing with through vehicles at the Bangerter Highway/3500 South 

Intersection in Utah.

(2)

GEOMETRIC DESIGN CONSIDERATIONS

Exhibit 1-12 and Exhibit 1-13 illustrate typical designs for DLT intersections with channelized 

right turns. Each of these exhibits depicts right-turn bypass lanes. A bypass lane is not always 

needed, and right-turning vehicles may also be served by turning right on the cross street similar 

to a conventional intersection. In this form, right-turning traffic volumes must pass through the 

downstream crossover. 

There are existing DLT intersection installations without channelized right turns as shown in 

Exhibit 1-14. This reduces the overall footprint and cost of the intersection. The non-channelized

right turns typically coincide with single displaced left turns, and their turning paths can be 

defined to discourage wrong-way movements (i.e., into the displaced left-turn lane). According 

to the Utah Department of Transportation (UDOT) DLT intersection guidelines, the main benefit 

of adding channelized right-turn or bypass lanes is to reduce the number of conflict points within 

the DLT intersection (effectively one conflict per leg bypassed), but the disadvantage is that this 

design requires a larger footprint.(3)

 

The design in Exhibit 1-12 is for a DLT intersection with displaced left-turn movements on all 

four approaches. This design reflects a shift of the through traffic lanes into the median in an 

attempt to minimize the need for additional right-of-way. At several locations where DLT 

intersections have been implemented as a retrofit to an existing conventional at-grade 

intersection, the existing median has been preserved, and there is no shift in the through lanes. 

Exhibit 1-13 illustrates a DLT movement at a three-leg intersection with the displacement on the 

major road. 
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Exhibit 1-12. DLT intersection with displaced left turns on all approaches. 
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Exhibit 1-13. Three-legged DLT intersection with displaced left turns on major road 

approach. 

Exhibit 1-14. DLT without channelized right turns.

RESOURCE DOCUMENTS

This Displaced Left Turn Intersection Guide is supplemental to major resource documents 

including but not limited to: 

• A Policy on Geometric Design of Highways and Streets (American Association of State 

Highway and Transportation Officials [AASHTO] Green Book)(4)

• Highway Capacity Manual (HCM)(5)
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• Manual of Uniform Traffic Control Devices (MUTCD)(6)

• Highway Safety Manual (HSM)(7)

• Other research documents that appear in this guide and are more specialized to specific 

areas include various National Cooperative Highway Research Program (NCHRP) 

reports, Transportation Research Board (TRB) papers, and Federal Highway 

Administration (FHWA) publications

The following are supplemental resource documents specific to DLT intersections: 

• Design and Operational Performance of Crossover Displaced Left-turn Intersections(8)

• The Parallel Flow Intersection: A New Two-Phase Signal Alternative(9)

• Travel Time Comparisons between Seven Unconventional Arterial Intersection 

Designs(10)

• Operational Effects of CFI Geometrics: A Deterministic Model for Continuous Flow 

Intersections(11)

• CFI Guideline: A UDOT Guide to Continuous Flow Intersections(2)
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CHAPTER 2— POLICY AND PLANNING

This chapter contains guidance on how to consider alternative intersections in general and DLT 

intersections in particular. This chapter summarizes policy and planning considerations related to 

DLT intersections. The remaining chapters of this guide will provide specific details of the 

multimodal, safety, operations, geometric design, and traffic control features of DLT 

intersections. 

Alternative intersections are often initially considered for operational or safety needs, and other 

key factors may include spatial requirements and multimodal needs. This chapter provides 

approximate footprints for different types of DLT intersections to allow for planning-level 

screening and feasibility analysis. 

 

PLANNING CONSIDERATIONS FOR ALTERNATIVE INTERSECTIONS AND 

INTERCHANGES

Alternative intersection evaluations may vary depending on the stage of the project development 

process. Each project stage can affect how policy and technical considerations are assessed. 

While the operational, design, safety, human factors, and signing controls should be considered 

at every stage of the development process, a planning level design evaluation may not require the 

same level of analysis or detailed evaluation of each consideration projects in later development 

stages. Evaluations should be as comprehensive as needed to answer key project questions for 

each unique project context. 

Serving Pedestrians and Bicycles

The most likely type of setting for a DLT intersection is along urban or suburban roads with high 

traffic volumes. These are locales where pedestrians and bicyclists regularly walk and bike. 

Therefore, roads and intersections must be specifically planned and designed to serve these 

users. 

DLT intersections come with specific pedestrian and bicyclist considerations and should be evaluated 

on a case-by-case basis. Pedestrians crossing at a DLT intersection may be required to cross more 

travel lanes than at a conventional intersection. Even if the number of lanes is similar, the crossing 

needs, crossing stages, and pathway configurations may be different compared to traditional 

intersections. Depending on pedestrian and bicyclist volumes and motor vehicle traffic volumes, a 

DLT intersection may not be an appropriate option for some locations due to increased conflicts with 

motor vehicles. DLT intersections being advanced for consideration may need to include other ways 

to accommodate pedestrians, such as by providing grade-separated pedestrian facilities that coincide 

with the surrounding land use context.

Many DLT intersections are set up for pedestrians to cross in multiple stages with median islands 

providing a refuge. In these cases, storage provided for pedestrians should also be compliant with the 

Americans with Disabilities Act (ADA) and be developed using published information or principles 

from traditional intersection forms. Multi-stage crossings may increase crossing time and are 
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sometimes more indirect than comparable conventional intersections. These crossings must 

include elements or features supporting their ability to serve the range of pedestrians, including 

individuals with visual impairments or users with other special needs. 

Accessible pedestrian signals (APS) are generally required where pedestrian signals are provided 

to serve pedestrians with visual impairments. APS should be included, or at least not precluded 

for future implementation, at DLT intersections. Transportation professionals, local agencies, 

and communities representatives may wish to jointly determine how to best implement APS 

equipment. 

Depending on the crossing configuration at a DLT intersection, pedestrians may cross 

“diagonally” between refuge islands adjacent to the left-turn lanes. These pedestrians walk 

between left-turning and through traffic. This type of movement places moving traffic on two 

sides of pedestrians, and requires special care and consideration to develop design elements to 

serve pedestrians with visual or cognitive impairments. In these cases, wider median islands 

and/or wider outer separations may best serve pedestrian movements. 

As with any intersection, facilities for bicyclists can be provided on the road using marked 

bicycle lanes, shared lanes and cycle tracks. However, special care is required for DLT 

intersections to consider and address how bicyclists will interact with different paths of vehicles. 

Off-street bicycle paths or shared-use paths can be included at DLT intersections if they are 

configured to cross at appropriate locations at the intersection (e.g., at stop bars where 

conflicting traffic movements enter). Typical locations for shared-use path crossings would be 

the same as the locations of crosswalks. 

Traffic Volume Relationship

Exhibit 2-1 conceptually depicts the relationship of conventional intersections, alternative 

intersections, and grade separations in their ability to serve increasing traffic volumes. 
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Exhibit 2-1. Relationship between total entering volume and intersection type.

A DLT intersection has a larger footprint compared to conventional intersections. With right-ofway restrictions, it can be difficult to widen or add lanes; therefore, careful planning is required 

during the initial design of a DLT intersection. Exhibit 2-2 and Exhibit 2-3 illustrate the 

estimated footprint for a DLT intersection compared to a conventional intersection. Exhibit 2-2 

shows a tangent alignment for through movements at the crossover intersections, while Exhibit 
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2-3 illustrates the undesirable deflections at the crossover intersections. The right-of-way 

footprint may affect any agency’s decision on whether to construct this type of intersection.

Exhibit 2-2. Footprint comparison of a DLT intersection with tangent alignments versus a 

conventional intersection. 
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Exhibit 2-3. Footprint comparison of a DLT intersection with deflected through alignments 

versus a conventional intersection. 

Costs specific to a DLT intersection are related to increased materials and additional signs and 

signals compared to conventional intersections. Additional signals can become a significant cost, 

particularly for a DLT intersection with left-turn crossovers on all four approaches. Construction 

costs associated with the DLT intersection may be offset to some extent by safety and 

operational improvements; however, this should be explored on a project basis through 

additional analysis. 

STAKEHOLDER OUTREACH

Similar to other transportation projects, stakeholder outreach is a critical part of the overall 

planning process. Successful implementation of the first DLT intersection in a community may 

result from explicit and proactive outreach and education to affected stakeholders and the general 

public. This would create opportunities to familiarize others with how the intersection works 

while creating opportunities to hear of general project and DLT intersection specific issues and 

considerations. Special considerations may include sharing how the left-turn movements of the 

DLT intersection require drivers to turn left prior to the main intersection and how pedestrian 
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movements differ from conventional intersection forms. Public information and educational 

campaigns prior to opening a DLT intersection can help promote an understanding of unique 

features. Creating multiple forums to engage the public (including presentations at local council 

or board meetings, briefs at community organization functions, and project-specific open house 

meetings) results in opportunities to listen to community interests and share objective 

information about the intersection form. 

Public outreach conducted during planning and design of an alternative intersection design can 

inform and educate the public about the proper use and benefits of the new form. Media 

campaigns through local newspapers, television, and public meetings can be effective methods of 

keeping the community informed. Exhibit 2-4 is an example of a pamphlet used by UDOT for a 

CFI (DLT intersection).(12) Once the intersection is open to the public, monitoring driver 

behavior and using law enforcement as necessary to promote proper use of the new form can aid 

driver acclimation.

Exhibit 2-4. CFI (DLT intersection) instruction card for UDOT.

(12)

The Ohio Department of Transportation (Ohio DOT) used a frequently asked question (FAQ) 

website to communicate project details for a DLT intersection constructed in Miami Township, 

OH. The website especially highlighted the significance of using a DLT intersection instead of a 

grade-separated interchange to retrofit the existing intersection and compared features of the 

DLT intersection with an interchange constructed 0.5 miles downstream of the project site.

(13)

The FAQ lists a comparison of costs for the two designs, describes the issues that had occurred at 

the intersection before the DLT intersection was constructed, and explains the reasoning behind 

the decision to construct a DLT intersection. 
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While not strictly public outreach, another newsletter was distributed to members of Ohio DOT 

in 2003 before any DLT intersections were constructed there. The one-page flier introduces the 

DLT intersection and describes its geometric layout and benefits (including benefits for 

automobiles and pedestrians).(14) The flier goes on to explain the economic benefit of a DLT 

intersection compared to a interchange and identifies possible locations for construction. 

The following communications and public involvement elements may be considered as part of 

the public outreach: 

• Expect opposition 

• Budget proactively

• Understand your audience

• Identify and measure success

• Manage expectations

• Demonstrate public accountability

• Tell an engaging story

FHWA has created alternative intersection and interchange informational videos and video case 

studies, which can be viewed on the FHWA YouTube channel 

(https://www.youtube.com/user/USDOTFHWA).(15) In addition, FHWA has developed 

alternative intersection brochures that can be found on the FHWA website 

(http://safety.fhwa.dot.gov).(16) Examples of this information are shown in the appendix. 

POLICY CONSIDERATIONS

Designing, operating, and managing a street and its intersections should align with the 

appropriate jurisdictional policies associated with that facility. The facility location and type can 

often dictate the appropriateness of the right-of-way and access management needs associated 

with alternative intersections. The degree to which motor vehicle throughput should or should 

not be prioritized over other modes also plays a role in determining the appropriateness of 

alternative intersections at specific locations.

Some of the policy considerations of a DLT intersection include the following: 

• Access management 

o Locations relative to adjacent signalized intersections – greater separation is 

needed between a DLT intersection and a conventional intersection than is needed 

between two conventional intersections 
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o U-turns – prohibited at the main intersection and generally not possible 

o Frontage roads – these are encouraged since access is typically restricted in a 

DLT intersection footprint 

• Operational measures of effectiveness

• Pedestrian facilities with access and wayfinding for persons with disabilities, including 

the requirements of the ADA and Section 504 (the Rehabilitation Act).(17)

• Bicycle facilities

• Design vehicle

• Snow removal and storage 

• Incident management

• Emergency response needs

PLANNING CONSIDERATIONS 

The following are planning considerations for an alternative intersection design: 

• Community goals – Outside of formalized land use policies, cities and communities 

often have general goals that provide insights about the nature and character of their 

community. These goals can range from concepts that preserve a historic character or 

identified heritage to creating walkable communities or complete streets. Other goals can 

be to encourage economic development by preserving existing business or residential 

areas while encouraging thoughtful development. Regardless of the specific goals or 

vision, these considerations may influence street and intersection design. 

• Surrounding land uses and zoning – DLT intersections are well suited for suburban and 

urban environments with relatively large parcels of auto-oriented land uses. They are 

more challenging to implement in urban environments, on streets with short block 

spacing or numerous driveways, or in dense areas with constrained right-of-way.

• Project context – Key questions that help to identify stakeholders for a particular project 

might include:

o What is the purpose and function of the existing or planned road facilities? 

o What are the existing and planned land uses adjacent to and in the vicinity of the 

road facilities? 

o Who will likely desire to use the road facilities given the existing and planned 

land uses? 
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o What are the existing and anticipated future socio-demographic characteristics of 

the populations adjacent to and in the vicinity of the existing or planned road 

facilities? 

o What are the perceived or actual shortcomings of the existing road facilities? 

o Who has jurisdiction over the facility? 

o Where is capital funding for the project originating (or expected to originate)? 

o Who will operate and maintain the facility? 

• Multimodal considerations – Pedestrian, bicycle, and transit needs should play a role in 

selecting an intersection form and developing design elements. 

• Access management – Access will need to be restricted for several hundred feet on an 

intersection approach with a DLT intersection. 

• Design vehicles – The intersection geometry will need to accommodate transit, 

emergency vehicles, freight, and potentially oversize and over weight vehicles. 

PLANNING CHALLENGES

The following are several challenges associated with planning DLT intersections:

• Driver education – Successful implementations of DLT intersections are often preceded 

by public outreach and education campaigns, which are typically not conducted for 

conventional intersection improvements. 

• Driver expectation – DLT intersections relocate left-turn movements from their 

conventional location. This is different from what most drivers would expect, and must 

be accounted for in the intersection planning and design. 

• Multimodal accommodation – As with any street segment or intersection, each 

configuration must consider and serve the various users who currently or may be 

expected to use the facilities. This should always include pedestrians and bicycles, 

understanding that the exact provisions may necessarily vary for each site. However, 

pedestrian facilities must always be made accessible. DLT intersections are generally 

compatible with transit as well.

• Sufficient corridor right-of-way – Most DLT intersections have a larger footprint and 

require more right-of-way than conventional intersections. An intersection approach with 

a DLT configuration can include at least two lanes (one left-turn lane and one right-turn 

lane) beyond the typical section of the street. Such right-of-way is prohibitively 

expensive or impactful at many intersections. On the other hand, the potential footprint of 

a DLT intersection configuration may be smaller compared to a conventional interchange

configuration that provides a comparable level of operational performance.
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• Frontage roads – These must be further offset from the main road. The intersection of 

the frontage road and cross street becomes challenging due to the adjacent intersection of 

the (displaced) left-turn lane and the cross street. 

PROJECT PERFORMANCE CONSIDERATIONS

Measuring the effectiveness of overall project performance depends on the nature or catalyst for 

the project. Understanding the intended specific operational, safety, and geometric performance 

context for each intersection or corridor including intended users can guide help determine 

project-specific performance measures. The project performance may be directly linked to the 

specific design choices and the specific performance of the alternatives considered. The project 

performance categories described below can influence and are influenced by the specific DLT 

design elements and their characteristics.

(18)

Accessibility

Chapter 3 of this guide describes accessibility as it relates to special consideration given to 

pedestrians with disabilities including accommodating pedestrians with vision or mobility 

impairments. However, for the purposes of considering a project’s general context and the 

performance considerations, the term “accessibility” goes beyond the conversation of policy 

related to ADA and Public Rights-of-Way Accessibility Guidelines (PROWAG) and is meant to 

be considered in broader terms.(17) With respect to considering applicable intersection forms for 

a given project context, accessibility is defined broadly as the ability to approach a desired 

destination or potential opportunity for activity using highways and streets (including the 

sidewalks and/or bicycle lanes provided within those rights-of-way). This could include the 

ability for a large design vehicle to navigate an intersection as much as it might pertain to the 

application of snow mobiles or equestrian uses in some environments or conditions. 

Mobility

Mobility is defined as the ability to move various users efficiently from one place to another 

using highways and streets. The term “mobility” can sometimes be associated with motorized 

vehicular movement and capacity. For the purposes of this guide, “mobility” is meant to be 

independent of any particular travel mode. 

Quality of Service

Quality of service is defined as the perceived quality of travel by a road user. It is used in the 

2010 Highway Capacity Manual to assess multimodal level of service for motorists, pedestrians, 

bicyclists, and transit riders.(5) Quality of service may also include the perceived quality of travel 

by design vehicle users such as truck or bus drivers. 

Reliability

Reliability is defined as the consistency of performance over a series of time periods (e.g., hourto-hour, day-to-day, year-to-year).
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Safety

Safety is defined as the expected frequency and severity of crashes occurring on highways and 

streets. Expected crash frequencies and severities are often disaggregated by type, including 

whether or not a crash involves a non-motorized user or a specific vehicle type (e.g., heavy 

vehicle, transit vehicle, motorcycle). In cases where certain crash types or severities are small in 

number, as is often the case with pedestrian- or bicycle-involved, it may be necessary to review a 

longer period of time to gain a more accurate understanding.

PROJECT DEVELOPMENT PROCESS

For the purposes of this report, the project development process is defined as consisting of the 

stages described below. Federal, state, and local agencies may have different names or other 

nomenclature with the overall intent of advancing from planning to implementation. Exhibit 2-5 

illustrates the overall project development process.

Exhibit 2-5. Project development process.

Planning Studies

Planning studies often include exercises such as problem identification and other similar steps to 

ensure there is a connection between the project purpose and need and the geometric concepts 

being considered. Planning studies could include limited geometric concepts on the general type 

or magnitude of project solutions to support programming. 

Alternatives Identification and Evaluation 

The project needs identified in prior planning studies inform concept identification, 

development, and evaluation. At this stage, it is critical to understand the project context and 

intended outcomes so potential solutions may be tailored to meet project needs within the 

opportunities and constraints of a given effort. FHWA describes context sensitive solutions as 

“... a collaborative, interdisciplinary approach that involves all stakeholders in providing a 

transportation facility that fits its setting.)

”(19) In considering the concept of “context sensitive 

design/solutions, this stage calls for meaningful and continuous stakeholder engagement to 

progress through the project development process. 
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Preliminary Design

Concepts advancing from the previous stage are further refined and screened during preliminary 

design. For more complex, detailed, or impactful projects, the preliminary design (typically 30-

percent design level plans) and subsequent documentation are used to support more complex 

state or federal environmental clearance activities. The corresponding increased geometric 

design detail allows for refined technical evaluations and analyses that inform environmental 

clearance activities. Preliminary design builds upon the work and geometric evaluations 

conducted as part of the previous stage (alternatives identification and evaluation). Some of the 

common components of preliminary design include: 

• Horizontal and vertical alignment design

• Typical sections

• Grading plans 

• Structures

• Traffic/intelligent transportation systems (ITS) 

• Signing and pavement markings 

• Illumination

• Utilities

Final Design

The design elements are advanced and refined in final design. Typical review periods include 60-

percent, 90-percent, and 100-percent plans before completing the final set of PS&E. During this 

stage, there is relatively little variation in design decisions as the plan advances to 100 percent. 

Functionally, in this stage of the project development process, the targeted performance 

measures have a lesser degree of influence on the form of the project.

Construction

Construction activities could include geometric design decisions related to temporary streets, 

connections, or conditions that facilitate construction. Project performance measures may relate 

to project context elements. 

SUMMARY OF DLT ADVANTAGES AND DISADVANTAGES

As described in Chapter 1 and the previous sections of this chapter, DLT intersections have 

unique features and characteristics related to multimodal considerations, safety performance, 

operations, geometric design, spatial requirements, constructability, and maintenance. 
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Exhibit 2-6 provides an overview of the primary advantages and disadvantages of DLT 

intersections for users, policy makers, designers, and planners to understand when considering 

this type of alternative intersection form.

Exhibit 2-6. Summary of DLT advantages and disadvantages.

Advantages Disadvantages

Non-Motorized Users

• Bicycles and pedestrians can be accommodated 

at-grade

• Bicyclists have refuge (room for bicycle box) 

in making two-stage left turns

• Pedestrians may require 2-stage crossings

• Some indirect movements may be necessary 

for pedestrians

• Longer pedestrian crossings 

• Unique challenges for visually imipaired 

pedesterians

Safety

• Fewer conflict points than interchanges (ramp 

terminals, exit/entrance ramps) and 

conventional intersections 

• Lower delay and fewer stops on major street 

could reduce rear-end crash rates

• Drivers may be less familiar with intersection

• Potential for wrong-way movements

• Issues with signal in flashing mode / going 

dark 

Operations

• Increase in lane-by-lane capacity due to 

efficient 2-phase or 3-phase signal operation

• Compatible with high-volume turning 

movements

• More green time for major movements offers 

better progression when used as a corridor 

solution

• Complex signal operations

• Pedestrian crossing time and phasing may limit 

cycle length flexibility

• Potential for additional user delay during offpeak periods 

• No right turn on red without bypass right turn 

lane

Access Management

• Compatible with access-restricted corridors • May change ingress/egress patterns to corner 

businesses or development

• Medians and wide separators required

Cost and Right-of-Way Impact

• Smaller footprint than interchange

• Lower cost than interchange

• Required right of way likely larger than 

conventional intersection

• More traffic signals, pavement, curbs and 

median/refuge islands
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CHAPTER 3— MULTIMODAL CONSIDERATIONS

This chapter provides an overview of multimodal facilities at DLT intersections and how 

provisions for pedestrians and bicycles should influence the overall planning and design of these 

intersections. Several of the guidelines presented here are based on elements of the AASHTO

Green Book, but applied within the unique context of a DLT intersection.

(4) The overall 

objective is to develop a design, regardless of the type of intersection, compatible with a 

Complete Street. A Complete Street is a facility that serves many types of users including 

freight, transit, and non-motorized users. 

DESIGN PRINCIPLES AND APPROACH

DLT intersection planning and design should consider a variety of transportation modes. The 

following elements should be considered when evaluating a DLT intersection: 

• A DLT intersection footprint may result in a wider overall street at the intersection, 

thereby widening the total pedestrian crossing distance. This can also increase the time it 

takes for bicyclists to ride through the main intersection area. Additional treatments may 

be necessary to mitigate these effects. 

• The unique movements of the DLT intersection (e.g., prohibited major street left turns at 

the main intersection) may create added enforcement needs for automobiles and bicycles. 

• Large vehicles require adequate lane widths at the crossover intersections to 

accommodate swept paths. Therefore, the geometry of the overall intersection and all its 

associated movements need to accommodate the design vehicle for the facility.

• Transit stops near a DLT intersection configuration will need to be strategically placed to 

support pedestrian access. 

This chapter describes the unique characteristics of the four primary non-auto modes 

(pedestrians, bicyclists, transit, and potentially oversize and overweight vehicles) that should be 

considered when analyzing and designing DLT intersections. 

PEDESTRIANS

DLT intersections require pedestrian crossings that differ from conventional intersections. The 

position of left-turn lanes between opposing through lanes and right-turn lanes presents 

pedestrians with an unfamiliar crossing scenario, and the DLT intersection’s wide geometric 

footprint can make it challenging to accommodate pedestrians as part of the traffic signal timing. 

To mitigate these issues, the design should include pedestrian islands (e.g., medians) to provide 

refuge, and the short cycle lengths associated with DLT intersection operations can help make 

pedestrian movements more comparable to crossing times at conventional intersections. 

Pedestrian crossing distances at DLT intersections are similar to those of large conventional 

intersections with channelized right turns. The design focus is to create crosswalks allowing 

pedestrians to move from the channelization to the outside of the intersection. The crosswalks 
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across the channelized right-turning streets can be configured with or without signals at the 

crosswalk. If there are multiple right-turn lanes, then a signalized pedestrian crossing should be 

provided. 

There are two ways to treat pedestrian crossings at DLT intersections. The first option is 

illustrated by the DLT intersection with displaced major street left turns shown in Exhibit 3-1. 

This DLT intersection in Dayton, Ohio uses pedestrian signals at the channelized right turns 

(with right turn on red [RTOR] prohibited) to facilitate pedestrians crossing the channelized 

right-turn lanes. Another feature of this DLT is that the crosswalks and pedestrian refuges are 

placed between the crossover left turns and the through-movement lanes so that left-turning 

vehicles do not conflict with pedestrians. The pedestrian refuges need to be adequate in size and 

width to meet ADA guidance, as well as accommodate larger volumes of pedestrians when 

appropriate, including people walking bikes and strollers. Note that no central median island is 

provided for a pedestrian refuge. Instead, pedestrians cross the through-movement lanes in one 

stage.

Exhibit 3-1. DLT in Dayton, OH with two-stage crossings of main line.

(1)

In the second option, as reflected in several DLT intersection installations, the displaced left

turns will yield to the pedestrians in the crosswalk (Exhibit 3-2). A separate signal phase is 

needed for a protected pedestrian crossing by providing protected-permissive left-turn phasing 

for the displaced left turns. 
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Exhibit 3-2. Possible pedestrian movements with one-stage crossings of main line at a DLT 

intersection. 

Signalized and Unsignalized Pedestrian Crossings 

The channelized right-turn lanes at a DLT intersection may be unsignalized. NCHRP Report 674 

provides crossing solutions at channelized turn lanes for pedestrians with vision disabilities.(20) 

The following are considerations when planning or designing the channelized right turn to 

accommodate pedestrians:

• Provide geometric layouts resulting in target speeds for the right-turn lane by considering 

an arrangement of compound curves rather than a single sweeping circular curve

• Provide appropriate sight distance and lighting for approaching motorists to see activity 

at the crosswalk, as well as sight distance for pedestrians to see oncoming traffic

• Strongly consider signalized treatment at multilane channelized turn movements

NCHRP Report 562: Improving Pedestrian Safety at Unsignalized Crossings, supplemented with 

research on the rectangular rapid-flashing beacon (RRFB), provides guidance on improving 

pedestrian safety at unsignalized crossings.(21)

 The RRFB is a pedestrian-actuated set of amber 

light-emitting diodes (LEDs) that rapidly flashes when actuated. The two NCHRP reports noted 

in this section provide tools for developing appropriate crossing treatments based on vehicle 

speeds, traffic volumes, and anticipated number of pedestrian crossings. Potential crossing 

treatments may include any of the following, or in some cases a combination of two or more of 

these: pavement markings, signing, flashing beacons, RRFBs, pedestrian hybrid beacons (PHBs), 

raised crosswalks and fully signalized crossings that are coordinated with the main intersection, 

each with the consideration for speech messages for visually impaired pedestrians. Exhibit 3-3 

suggests potential channelized right-turn geometry.(22) 
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Exhibit 3-3. Channelized right-turn design.

(22) 

Single versus Two-Stage Pedestrian Crossings

The signal control at the main DLT intersection typically operates as a two-phase signal with 

short cycle lengths to promote signal progression. Short cycle lengths are generally not possible 

with single-stage pedestrian crossings due to the time required to serve the pedestrian phase on a 

long crossing. However, short cycle lengths are possible if pedestrians are required to cross in 

two stages.

 (23) The tradeoff from a pedestrian standpoint is a potentially long delay for a onestage crossing versus two shorter increments of delay for a two-stage crossing, plus the need to 

wait in a refuge between crossing stages. 

Depending on the crossing scenario, pedestrians may cross between refuge islands adjacent to 

the left-turn lanes, as shown in Exhibit 3-4. These pedestrians stand between left-turning and 

through traffic. This type of movement places moving traffic on two sides of pedestrians, which 

can be especially challenging for pedestrians with visual or cognitive impairments. Wider 

median islands and/or wider outer separations are highly recommended to store pedestrians and 

allow space for bicycles.
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Exhibit 3-4. Refuge islands between left-turn and through lanes. 

Conflict Points

A pedestrian/vehicle conflict point exists anywhere a pedestrian walkway crosses the vehicular 

travel lanes. The conflict points for single-stage crossing DLT intersections with displaced left 

turns on two approaches and four approaches are illustrated in Exhibit 3-5 and Exhibit 3-6. The 

conflict points for two-stage crossing DLT intersections with displaced left turns on two 

approaches and four approaches are illustrated in Exhibit 3-7 and Exhibit 3-8. 
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Exhibit 3-5. Pedestrian-vehicle conflict point diagram for a DLT intersection with two 

displaced left turns with a single-stage crossing. 

Exhibit 3-6. Pedestrian-vehicle conflict point diagram for a DLT intersection with four

displaced left turns with a single-stage crossing. 
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Exhibit 3-7. Pedestrian-vehicle conflict point diagram for a DLT intersection with two 

displaced left turns with a two-stage crossing. 

35

Exhibit 3-8. Pedestrian-vehicle conflict point diagram for a DLT intersection with four

displaced left turns with a two-stage crossing. 

For comparison, Exhibit 3-9 shows pedestrian-vehicle conflict points for a conventional 

intersection. 
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Exhibit 3-9. Pedestrian-vehicle conflict point diagram for a conventional intersection. 

A DLT intersection with two displaced left turns has 20 pedestrian-vehicle conflict points for a 

one-stage crossing and 18 for a two-stage crossing. A DLT intersection with four displaced left 

turns has 20 pedestrian-vehicle conflict points for a one-stage crossing and 16 for a two-stage 

crossing. A conventional intersection has 24 pedestrian-vehicle conflict points. Thus, each of the 

four DLT crossing configurations has fewer pedestrian-vehicle conflict points than a 

conventional intersection. 

ADA and PROWAG Accessibility Considerations

Accessibility was previous described in Chapter 2 in the broader contexts of considering a 

project’s contextual environment and the ability for various users to approach a desired 

destination or potential opportunity for activity using highways and streets (including the 

sidewalks and/or bicycle lanes provided within those rights-of-way). In this section, accessibility 

is explicitly focused on the policies related to ADA and Public Rights-of-Way Accessibility 

Guidelines (PROWAG).(17) Special consideration should be given to pedestrians with 

disabilities, including accommodating pedestrians with vision or mobility impairments. Being 

relatively new on a national level, specific guidance for “Accessible MUTs” is not yet available. 

However, general accessibility principles can be borrowed from other forms of intersections and 

applied here. The United States Access Board provides many additional resources on 

accessibility and specific requirements for Accessible Public Rights of Way, which the 

transportation professional should refer to and be familiar with.(17)

The basic principles for accessible design can be divided into the pedestrian walkway and the 

pedestrian crossing location. For the pedestrian walkways, the following considerations apply: 

• Delineate the walkway through landscaping, curbing, or fencing to assist with wayfinding 

for blind pedestrians 
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• Provide sufficient space (length and width) and recommended slope rates for wheelchair 

users and other non-motorized users such as people pushing strollers and walking 

bicycles

• Construct an appropriate landing with flat slope and sufficient size at crossing points

For pedestrian crossing locations, these additional considerations apply: 

• Provide curb ramps and detectable warning surfaces at the edge of the sidewalk and 

transition to the street

• Provide accessible pedestrian signals with locator tone at signalized crossings

• Locate push-buttons to be accessible by wheelchairs and adjacent to the crossing at a 

minimum separation of 10 feet

• Use audible speech messages where spacing is less than 10 feet, or where additional 

narrative for the expected direction of traffic is needed

• Align the crosswalk landing to the intended crossing direction

• Crosswalk width through the intersection should be wide enough to permit pedestrian and 

wheelchairs to pass without delay from opposing directions, and the medians should 

provide sufficient storage for all non-motorized users to safely wait when two-stage 

crossings are required

All pedestrians—but especially those with vision, mobility, or cognitive impairments—may 

benefit from targeted outreach and additional informational material created with pedestrians in 

mind. These outreach materials include information on crosswalk placement and intended 

behavior, as well as answers to frequently asked questions. For blind pedestrians, materials need 

to be presented in an accessible format, with sufficient descriptions of all features of the DLT 

intersection.

BICYCLISTS

A DLT intersection and its approach streets need to be designed with bicyclists in mind. 

Separated bicycle paths and shared-use paths should cross at stop bar locations where conflicting 

traffic movements are typically controlled by signals. Another approach is to provide grade 

separation for bicyclists.

Bike Lane Design at Right Turns

Four locations need to be addressed when planning and designing for bicycles at a DLT

intersection:

1. The entrance to the channelized right turn, which is a bicycle-vehicle conflict point 
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o If a bicycle lane is present, this movement can be accomplished similarly to the 

entrance to a channelized right turn at a conventional intersection. 

2. Traveling along the right-turn lane 

o Typically, right-turning vehicles and bicycles share the travel lane and, depending 

on their respective volumes and travel speeds, bicycles may choose to use the 

sidewalk. 

3. Traveling through the DLT intersection

o Green paint (see Chapter 8 for details) indicating the continuation of the bicycle

lane can delineate bicycle travel areas through the intersections. 

4. The right-turn lane end 

o Bicyclists traveling through on the cross road will conflict with right-turning 

vehicles trying to merge with traffic along the cross street. To address the 

bicyclist exposure at this location, the transportation professional can consider a 

perpendicular bicycle crossing of the right-turn lane, as illustrated in Exhibit 3-5 

above. 

Exhibit 3-10 and 3-11 highlight these conflict areas and summarize potential routes for bicyclists 

traveling through DLT intersections via on- and off-street facilities, respectively. 

Exhibit 3-10. Accommodating on-street bicycles through a DLT intersection. 
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Exhibit 3-11. Accommodating off-street bicycles through a DLT intersection. 

Bicycle Design for Left Turns

For bicyclists completing a left turn through the intersection, DLT intersections present similar 

challenges as large conventional intersections. There are three ways for a bicycle to complete a 

left turn at a DLT intersection: 

• Using a traffic lane to make the crossover movement, as a passenger car would make.

• With bicycle ramps to/from the sidewalks or shared-use paths in the vicinity of the DLT 

intersection. With this configuration, bicyclists will cross in the crosswalks. 

• If the DLT intersection geometry provides a pedestrian refuge island between the through 

lanes and the displaced left turns (as shown previously in Exhibit 3-4), a bicycle box can 

be placed in front of the far-side refuge to allow a two-stage left turn by bicyclists. This is 

shown in Exhibit 3-12. 

Exhibits 3-12 and 3-13 illustrate potential left-turning bicycle routes for two DLT configurations. 

Transportation professionals need to work with local agencies to determine dimensions for 

shared bicycle/pedestrian paths.
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Exhibit 3-12. Accommodating on-street left-turning bicycles with a bicycle box through a 

DLT intersection. 

Exhibit 3-13. Accommodating off-street left-turning bicycles through a DLT intersection. 
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TRANSIT VEHICLE CONSIDERATION

Buses travel through DLT intersections in the same manner as passenger cars. Stops are placed 

away from the main intersection. Location considerations are described as follows. 

Bus Stop Locations

The left-turn, through-, and right-turn movements at a DLT intersection do not merge or diverge 

at a single point near the main intersection. This runs counter to the traditional practice of 

locating transit stops near the crosswalk at the main intersection. Transportation professionals 

can consider two strategies to place transit stops and need to work collaboratively with transit 

agencies to finalize transit stop locations.

Midblock 

Locating a transit stop farther upstream or downstream of the DLT intersection could result in 

pedestrians crossing away from the main intersection. In these cases, a well-placed and welldesigned midblock pedestrian crossing needs to be considered. Exhibit 3-14 shows the potential 

location of a transit stop at a midblock location for one approach of a DLT intersection; the 

following elements regarding the location of the bus stop should also be taken into consideration: 

• It potentially forces passengers to walk a long way back to the intersection 

• It may encourage passengers to jaywalk rather than walk to a legal crossing point 

• It makes it difficult to accommodate transfer between routes on the crossing streets 

because of the long walking distances involved 

However, other factors may require such a bus stop placement. When midblock stops are used, 

signal control such as a RRFP, a pedestrian hybrid beacon, or a traditional midblock signalized 

crossing should be considered.
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Exhibit 3-14. Potential transit midblock stop location in a DLT intersection. 

Main Intersection

The second option is to develop a near-side bus stop on the channelizing island at the main 

signal. Exhibit 3-15 shows a potential near-side location using a short bus lane, while Exhibit 3-

16 illustrates a bus stop located in the travel lane. The following considerations apply to nearside bus stops: 

• At conventional intersections, when bus routes cross at an intersection, it is often 

desirable to locate pairs of stops on the same corner (one near-side, the other far-side) to 

accommodate transfers between routes. However, this approach is not possible at a DLT 

intersection—passengers must cross the street to transfer—but it is nevertheless 

preferable to the long walk involved with transferring between midblock stops. 

• Through buses can stop at the stop bar at the main intersection in the travel lane, or in a 

short bus lane or pullout adjacent to the channelizing island. The island needs to be long 

enough to accommodate a design bus and wide enough to meet ADA standards at the 

door locations. As buses may experience delay re-entering the travel lane from a pullout 

or bus lane, a queue-jump signal phase can be considered. A queue-jump signal provides 

the bus a few seconds of green before or after the parallel signal phase to allow the bus to 

merge into the general travel lane with minimal delay. The stop bar for a bus lane may be 

set forward from the general traffic stop bar, as it does not conflict with the swept path of 

left-turning traffic from the cross street.
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• Bus stops for right-turning buses should stop close to the crosswalk in the right-turn 

bypass lane. The bus stop is typically before the crosswalk if the bus stops in the lane (no 

vehicle can pass the bus), or just after the crosswalk in a pullout so pedestrians can cross 

behind the stopped bus. 

• Transit stops for left-turning buses can stop in the displaced left-turn lane at the stop bar 

if a wide-enough median is provided to accommodate passengers (see Exhibit 3-16). 

Another bus stop option for left-turning buses uses the short bus lane or pullout option 

described above (see Exhibit 3-15); in this case, a special bus phase will need to be 

provided for the bus to safely make its turn. 

Exhibit 3-15. Potential nearside stop locations with pullouts.
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Exhibit 3-16. Potential stop locations in travel lanes. 

Bus stops are not necessarily provided at every DLT intersection because the surrounding land 

uses may not be oriented toward transit users. Should stops be necessary, a collaborative process 

between street and transit agencies can help finalize the stop locations and assess implementing

transit-supportive treatments, such as queue jumps. 

HEAVY VEHICLE CONSIDERATIONS

The effects of the DLT crossover and other turning movements should also be considered with 

regard to heavy vehicles. Unlike alternative intersection treatments such as roundabouts, DLT 

intersections do not usually contain aprons or other design elements that are intended to be 

traversable by trucks and other large vehicles. When designing the specific elements of the 

DLT—such as left-turn crossovers, left turns onto the cross street at the main intersection, and 

right-turn bypass lanes—it is crucial to consider the appropriate design vehicle and the 

possibility that large vehicles may travel through the DLT. 
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CHAPTER 4— SAFETY

At this time, little is documented about the safety performance of DLT intersections as there 

have been insufficient numbers of intersections open for an extended period of time. DLT 

intersections, like many alternative intersection designs, offer several potential safety advantages 

compared to the conventional intersection by reducing conflict points and channelizing turning 

movements. This chapter summarizes the safety performance at DLT intersections based on 

studies completed by state agencies and recent research efforts. 

SAFETY PRINCIPLES

An appropriate level of safety assessment corresponding to the stage of the project development 

process (planning, alternatives identification and evaluation, preliminary design, final design, 

and construction) supports decisions about DLT intersections. The analysis should be consistent 

with the available data, and the data should be consistent with the applied tools. Multimodal 

safety principle—including vehicle-pedestrian and vehicle-bicycle conflict points, accessibility, 

and crossing options—are discussed in Chapter 3. 

Reduced Vehicle-Vehicle Conflict Points

While crash data are often used to develop models or other tools that can ultimately help 

professionals make safety decisions about transportation facilities, crash data are often limited or 

completely unavailable for some types of facilities. In the case of DLT intersections, the small 

number of existing intersections (approximately ten) makes it difficult to make inferences or 

develop tools related to their safety performance or expected crash frequency or severity.

Based on the design and operation of the intersection, however, it is possible for a DLT 

intersection to offer better safety performance over a conventional intersection. In lieu of crash 

data, one often-applied strategy is to examine the number of conflict points at an intersection. 

While no mathematical relationship between conflicts and collisions has been clearly 

documented, conflicts are correlated with collisions and are often used as a surrogate measure, 

particularly to compare different intersection forms. It is common to consider both lane-by-lane 

conflicts and an aggregated conflict analysis that treats each movement as one lane; the latter 

approach will be presented here for the sake of simplicity. Exhibit 4-1 shows the number of 

vehicle-to-vehicle conflict points present at various forms of the DLT intersection compared with 

conventional intersections. While the DLT intersection offers no reduction in conflict points for a 

three-leg intersection, it results in a 6- to 12-percent decrease in conflict points for a four-leg 

intersection.
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Exhibit 4-1. Conflict point comparison. 

Number of 

Intersection Legs

Number of Crossovers 

on DLT

Conflict Points

Conventional DLT

3 1 9 9

4 2 32 30

4 4 32 28

Exhibit 4-2 shows the conflict points of a conventional intersection. The total number of conflict 

points is 32. Exhibit 4-3 shows the conflict points of a DLT intersection with left-turn crossovers 

present on the mainline approaches. The total number of conflict points in this case is 30 

compared to the 32 conflict points at a conventional intersection. Exhibit 4-4 shows the conflict 

points of a DLT intersection with left-turn crossovers present on all approaches. The total 

number of conflict points in this case is 28. The slightly lower number of conflict points could 

translate to fewer potential collisions.

Exhibit 4-2. Conflict point diagram for a conventional intersection. 
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Exhibit 4-3. Conflict point diagram for a DLT intersection with two displaced left turns. 

Exhibit 4-4. Conflict point diagram for a DLT intersection with four displaced left turns. 

Human Factors, Principles, and Considerations

A human factors study performed by Dowling College examined a DLT intersection in Shirley, 

NY (shown in Exhibit 4-5) to explore driver comfort and confusion. The study found “about 80 

percent of the first time users of the [DLT intersection] expressed positive comments about the 

design,” with that figure increasing to 100 percent after a week of driving.(24) 
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Exhibit 4-5. Dowling College DLT intersection in Shirley, NY.

(1)

There are several design features of the DLT configuration that may be counterintuitive to some 

drivers. The following information could help minimize driver confusion: 

• Drivers are familiar with making left-turn maneuvers at the main intersection. In the case 

of a DLT intersection, the indirect left turn occurs several hundred feet in advance of the 

main intersection. This requires drivers to anticipate the left turn in advance of the main 

intersection, so signing needs to be well-designed and complement the geometry of the 

intersection.

(5)

• The design features of a DLT intersection and the relocation of turn movements at the 

main intersection presents the possibility of wrong-way movements. Wrong-way 

movements can be reduced by providing adequate signage, pavement markings, and, 

most of all, the geometric design of the street, including appropriate channelization and 

orientation of the horizontal alignments (see Chapters 7 and 8).(9)

OBSERVED SAFETY PERFORMANCE

There are limited safety related studies for the small number of existing DLT intersections to 

conclude safety performance based on observed data. 
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SAFETY CONSIDERATIONS

The DLT intersection introduces some unique operational qualities not present in the 

conventional intersection. These elements are discussed in the following sections. 

Pedestrian and Bicyclist Right-turn Movements

Similar to conventional intersections, four conflict areas exist between vehicles and bicyclists, as 

well as between vehicles and pedestrians along the length of the right-turn bypass lane at DLT 

intersections: 

• Conflict between vehicles and pedestrians at the signalized or unsignalized pedestrian 

crossing at the 90-degree turn of the right-turn bypass lane 

• Conflict between right-turning vehicles and through bicyclists at the entrance to the 

channelized right-turn lane 

• Limited width for right-turning cyclists sharing the channelized right-turn lane with 

automobiles 

• Conflict between right-turning vehicles merging along the cross road and through 

bicyclists on the cross road along the merge lane end section

Chapter 3 provides techniques for addressing these conflicts, and Chapter 8 provides more 

details associated with specific signing and pavement marking treatments. 

Potential for Wrong-way Movements 

The crossover intersection has the potential for wrong-way movements, as well as path overlap 

as vehicles travel through the crossover curves. Designers should consider path alignment 

through the signal to position vehicles at the stop bar to aim vehicles to the receiving lane 

beyond the intersection and not rely solely on signing and pavement markings for guidance. 

Assuming Exhibit 4-6 is oriented east-west horizontally, it shows the eastbound left turns align 

directly with the opposing westbound throughs, which is undesirable. 
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Exhibit 4-6. Undesirable crossover intersection layout. 

Exhibit 4-7 shows the eastbound left turns are oriented away from the oncoming westbound 

lanes, which is desirable. This configuration provides a tangent alignment along through lanes in 

the area of the crossover intersection. Chapter 8 provides specific signing and pavement marking 

details to supplemental desirable geometry.

Exhibit 4-7. Desirable crossover intersection layout. 
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At the main intersection, as well as the crossover intersections, the road alignment of the through 

movements is a particular focus. Curvature (e.g., sharper than expected) through a signalized 

intersection may result in approaching vehicles not appropriately aligning and entering opposing 

left-turn lanes. Applying basic geometric principles to allow for appropriate curve lengths and

tangents between curves results in appropriate natural paths through the intersections. Chapter 7 

provides guidelines for developing a layout meeting overall basic street design principles. 

INCIDENT RESPONSE CONSIDERATIONS

This section presents incident response considerations for DLT intersections. 

Loss of Power to the Traffic Signals 

Many agencies now require backup batteries and a natural gas generator in traffic signal systems 

in case of power failures. Given the unconventional geometry of a DLT intersection, there is 

potentially a greater benefit from installing a battery backup or generator than at a conventional 

intersection. For example, a DLT intersection in Baton Rouge, LA contains backup batteries and 

a natural gas generator for use in the event of power failure.(25)

Intersection Blocked

There is potential for the crossover to be blocked during crashes or incidents where stoppage and 

subsequent queuing of one movement (either the left-turn crossover or the through vehicles) 

could block the other movement. These situations can be mitigated by constructing shoulders or 

wide lanes to move vehicles around the blockage, but these treatments may also lead to higher 

speeds. In addition, metering and signal coordination with upstream and downstream 

intersections minimizes the likelihood of blockages in non-crash situations.(24)

The use of mountable curbs in the crossover area could help facilitate emergency vehicle access 

to the crossover lanes. Frontage roads could also provide access to channelized right-turn lanes. 

Emergency Response

Emergency vehicle preemption (e.g., fire preemption) is provided for many signalized 

intersections. To minimize response time, an emergency response vehicle should be able to 

travel through all signalized intersections within the DLT configuration without stopping 

(completing a left turn, through movement, or right turn as illustrated in Exhibit 4-8). The signals 

would be coordinated to allow the progression when preempted, as shown in Exhibit 4-8. 

Four-leg DLT intersections, while restricting direct left turns, do not install physical objects 

within the primary intersection (intersection of major and minor cross roads) that would 

physically block emergency vehicles from making direct left turns. Direct left turns at four-leg 

DLT intersections are denied exclusively by signing, signal indications, and pavement markings. 

Emergency vehicles using sirens and flashing lights as they approach a four-leg DLT intersection 

and desiring to turn left can make a direct left turn after verifying vehicles with conflicting 

movements have yielded the right-of-way. A direct left turn could be beneficial to emergency 

vehicles if the left-turn crossover lanes are blocked by queued traffic or disabled vehicles. 
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Exhibit 4-8. Emergency preemption movements on one approach of a DLT intersection. 

SAFETY EVALUATION CONSIDERATIONS

Given the limited available data, safety at a DLT intersection should be evaluated by assessing 

conflict points and driver expectancy. There are no crash modification factors (CMFs) specific to 

DLT intersections. 
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CHAPTER 5— OPERATIONAL CHARACTERISTICS

This chapter provides information on the unique operational characteristics of DLT intersections

and how they affect elements such as traffic signal phasing and coordination. The guidance 

presented here builds on existing DLT studies, which include operational performance studies, 

comparative performance studies, and simulation analysis. The chapter also provides guidance 

relating to design elements, such as driveways, that could affect the operational performance of 

DLT intersections. It is intended to help transportation professionals understand the unique 

operational characteristics of DLT intersections and prepare them for conducting operational 

analysis as described in Chapter 6. 

OPERATIONAL PRINCIPLES

The DLT intersection is often implemented as a treatment to maximize throughput at an 

intersection. DLT configurations exhibit operational benefits specifically when a heavy left turn 

conflicts with a heavy through movement. The distinguishing feature of a DLT intersection is the 

left-turn crossover, which serves left turns at a signalized intersection upstream of the main 

intersection. The crossover intersection then carries the left turns to the cross street on the left 

side of the two-way traffic at the main intersection. This enables the left turns to move during the 

same signal phase as the through movement. Removing the left-turn movements from the main 

intersection reduces signal phases, which in turn leads to higher capacity for the intersection. 

Exhibit 5-1 illustrates concurrent movements for the east-west arterial at a conventional

intersection and a DLT intersection. Concurrent movements for the north-south arterial are 

analogous. 
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Exhibit 5-1. Concurrent movements for east-west arterial at conventional intersection and 

DLT intersection. 
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Traffic Signal Phasing 

The MUTCD presents the current practice regarding traffic control devices, but the DLT 

intersection presents additional challenges regarding signal control not explicitly addressed in the 

MUTCD.

(6) A DLT configuration consists of a signalized intersection on one or more approaches 

along with a signal at the main intersection. Exhibit 5-2 shows the typical locations of signalized 

intersections within a DLT configuration; Intersection 1 represents the main intersection while 

Intersections 2 through 5 represents the crossover intersections. DLT intersections typically have 

shorter cycle lengths than similarly sized traditional intersections as a result of the reduced 

number of phases and the need to reduce queue lengths between the closely-spaced intersections. 

Exhibit 5-2. Typical DLT intersection signal locations. 

The DLT intersection can consist of up to five signalized intersections depending on the number 

of crossovers. The five signals, as shown in Exhibit 5-2, can be operated either with separate 
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controllers or with a single controller. Coordination of the traffic signal controllers is necessary 

when multiple signal controllers are used to control each signalized intersection separately at a 

DLT intersection. Sample signal phasing for a DLT intersection where five separate signal 

controllers are used is depicted in Exhibit 5-3. This concept does not show the pedestrian 

movements in the diagram, but if pedestrian refuge islands are provided between the displaced 

left turns and through movements, as described in Chapter 3, pedestrian crossings are 

accommodated within the phasing shown. 

Exhibit 5-3. Two-phase signal phasing at five separately controlled signalized 

intersections within a DLT intersection. 

Sample signal phasing for a DLT intersection where one signal controller is used is depicted in 

Exhibit 5-4. This illustrates that pedestrians are accommodated in a leading phase and the 

displaced left turns are accommodated after the pedestrian phases are completed.
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Exhibit 5-4. Signal phasing for a DLT intersection with a single controller. 

Exhibit 5-5 shows a sample signal phasing scheme for a DLT intersection with displaced left

turns only along the major street and conventional protected left turns along the side street. 
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Exhibit 5-5. Signal phasing for a DLT intersection with major street displaced left turns

with a single phase crossing for pedestrians. 

Traffic Signal Coordination 

The multiple signalized intersections contained within a DLT intersection are usually 

coordinated so certain movements at separate intersections essentially operate during the same 

phase. An example is illustrated in Exhibit 5-6: 

• In Step 1, the left-turn crossover upstream of the main intersection may give green to 

crossover vehicles at the same time the minor street movements occur at the main 

intersection. 

• By the time the crossover vehicles reach the main intersection, Step 2 (the next phase) 

will have begun, allowing the left turns to discharge at the main intersection. 
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Exhibit 5-6. Typical signal coordination. 

OPERATIONAL CONSIDERATIONS

DLT intersections are often used in locations where overall demand approaches the capacity of a 

conventional intersection form. 

Access Management

Maintaining or providing access to homes and businesses near a DLT intersection can be 

accomplished by using frontage roads and other access management treatments; however, it can 

result in the following operational impacts: 

• Weaving movements into and out of driveways 

• A need for U-turns at the main intersection or adjacent intersections

• Driver confusion related to wayfinding 

DLT intersection implementation typically restricts access to parcels situated in the quadrants of 

the main intersection. Access to these parcels can be accommodated via right-in/right-out 

configurations from the channelized right-turn lanes. The NCHRP Report 420 “Impacts of 

Access Management Techniques” discusses design, location, and spacing of driveways in 

general, and similar principles apply for DLT intersections.

(26)

U-turn movements are typically prohibited at the main intersection of a DLT intersection due to 

conflicts with other movements. To facilitate egress and easy movement of traffic from 

driveways in either direction of the approach, U-turn crossovers can be provided between the 

main intersection and the left-turn crossover. One such U-turn movement using a median 

opening—implemented in Baton Rouge, LA—is shown in Exhibit 5-7. Median width at the Uturn crossover is designed to accommodate the design vehicle making a U-turn. 
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Exhibit 5-7. Location of U-turn, frontage road, and driveway at DLT intersection in Baton 

Rouge, LA.(1)

60

Since direct access to adjacent properties is restricted in a DLT configuration design, frontage 

roads can provide access to these properties. General features of frontage roads and their typical 

layouts are detailed in the AASHTO Green Book. (2) The AASHTO Green Book provides 

guidance to maintain outer separation. 

Chapter 10 of NCHRP Report 420 presents guidelines for one-way and two-way frontage roads 

and their key features.

(26) Exhibit 5-7 shows the frontage road design at the DLT intersection in 

Baton Rouge, LA. 

System-Wide Considerations 

DLT intersections can be used in series with conventional intersections or other DLT 

intersections. The first corridor-wide installation of a DLT facility occurred on Bangerter 

Highway in Salt Lake City, UT. UDOT developed a corridor plan for the Bangerter Highway 

with eight DLT intersections and one DDI, as shown in Exhibit 5-8.(12) The UDOT DLT 

guidelines address the Bangerter Highway corridor. These guidelines indicate several design 

elements that were incorporated into the initially constructed DLT intersections were refined in 

the construction of those that followed. Specifically, the cost of the first DLT intersection was 

especially high due to the right-of-way required to facilitate the channelized right turns. So, 

subsequent DLT intersections were constructed without these channelized right turns. The 

guidelines also indicate that signage and signal design have “evolved” with the development of 

subsequent DLT intersections in Utah. 
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Exhibit 5-8. Bangerter Highway Corridor in Utah.(12) 

COMPARATIVE PERFORMANCE STUDIES

Limited field studies of constructed DLT intersections have been completed to date, but it is 

possible to draw conclusions about the operational effects of DLT intersections simply based on 
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their design. In particular, the simultaneous movement of the left-turn and through traffic at DLT 

intersections promotes progression of traffic platoons on the arterial, increases vehicular 

throughput, and reduces travel time along a corridor. 

Two-phase signals typically result in more efficient signal operations compared with multi-phase 

signals (e.g. the typical eight-phase signal) for accommodating full access movements due to the 

reduced lost time per cycle. Two-phase signals provide flexibility for progression along corridors 

and/or certain travel patterns, as well as relatively short cycle lengths depending on the 

pedestrian crossing distance. This reduced cycle length also leads to shorter queues on the 

intersection approaches, as well as within the DLT itself, given that it is made up of multiple 

signalized intersections. 

According to the 1996 Traffic Control Systems Handbook, a DLT intersection has 60-percent 

more capacity than a similarly sized conventional intersection.

(27) Another study compared the 

increased capacity associated with a grade separation with that of a DLT, showing similar 

results.

Simulation Model Studies

A significant amount of research on DLT intersections was produced by Reid and Hummer, who 

compared several alternative intersections in a simulation analysis of intersection operations.(10)

The authors concluded it was competitive with the other alternative intersection designs in terms 

of delay, queues, and number of stops. The authors also stated “the displaced left turn 

intersection may need the smallest amount of right-of-way of all the unconventional designs” 

examined.(10)

A sensitivity analysis using the microsimulation software VISSIM was performed as part of the 

research included in FHWA’s Alternative Intersection Informational Report.(25) Under four 

scenarios that varied the number of crossovers, lanes on the major street and minor street, and 

volumes on the major street and minor street, the analysis revealed the following results: 

• For each case, the DLT form resulted in increased capacity, as well as decreased queues, 

delay, and number of stops, compared to a conventional intersection 

• The benefits of the DLT intersection were more pronounced when traffic volumes 

increased

• The DLT configuration performed well regardless of the volume balance regarding leftturning, through, and right-turning vehicles 

All cases had signal timings adjusted for pedestrian presence. In the absence of pedestrians, cycle 

lengths can be lowered resulting in average intersection delay in the range of 14 to 19 

seconds/vehicle (s/veh) at low and medium traffic volumes for one of the cases. The details 

associated with this sensitivity study can be found in the appendices. The results are summarized 

below in Exhibit 5-9. 

For each of the cases modeled, the DLT intersection consistently outperformed the conventional 

intersection with respect to vehicle throughput, vehicle delay, number of stops, and queue length. 
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The operational improvement of the DLT intersection over the conventional intersection was 

notable at relatively low traffic volumes, but greater benefits were achieved as traffic volumes 

increased. Reducing the number of cycle phases reduced vehicle delay and increased the 

intersection capacity. 

Exhibit 5-9. Comparative simulation results.

(25) 

Comparison Item

Percent decrease for DLT compared to conventional intersection

Four displaced left turns Two displaced left turns

Intersection delay, with 

mainline flows balanced 10 to 90 % 36 to 39 % 

Intersection delay, with 

mainline flows unbalanced 69 to 82 % 30 % 

Number of stops, nonsaturated conditions 15 to 30 % 

Queue length 34 to 88%

Throughput, with mainline 

balanced flows -16 to -30 % -34 to -88% 

Throughput, with mainline 

flows unbalanced - 12 to -25 % -10 to -14 % 

Even with a single signal timing plan, the DLT intersection worked effectively for the 

combinations of traffic flows (low, medium, and heavy) studied. This is unique and can be useful 

for intersections that cannot implement multiple signal timing plans. 

Regarding left-turn capacity, a 1974 study from the United Kingdom found the DLT intersection 

could increase capacity and decrease delay for right-turning traffic (or left-turning traffic in 

countries with a right-hand traffic convention).(28) A 1994 study concluded that under balanced 

volumes and similar lane configuration, the upstream crossover of a DLT intersection has 

approximately twice the left-turn capacity as a conventional intersection.

(29) 

Approaches of a DLT intersection that have the left-turn crossovers cannot accommodate median 

breaks within a distance of approximately 600 to 700 feet of the main intersection depending on 

the design of the left-turn crossovers. Therefore, driveways in these areas need to be rightin/right-out only. 
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CHAPTER 6— OPERATIONAL ANALYSIS

The previous chapter presented operational characteristics unique to DLT intersections. To 

support decisions regarding the choice and design of a DLT intersection there needs to be an 

appropriate level of traffic operations analysis corresponding to the stage of the project 

development process. The level of analysis needs to be consistent with the available data, and 

that data needs to support the applied analysis tools. Vehicular traffic operations coincide with 

multimodal considerations. Final intersection configurations and associated signal timing should 

be in balance with multimodal needs for each unique project context. 

A DLT is a system of multiple signalized intersections. As such, an operational analysis needs to 

consider the effects of and relationship between the multiple signals. 

Available data could include the following elements:

• Average daily traffic (ADT)

• Speed (posted, design, or 85th percentile)

• Weekday and weekend peak-hour turning movement counts 

• Weekday and weekend off-peak turning movement counts 

• Pedestrian volume at the intersection

• Bicycle volume at the intersection

• Proportion of the traffic stream composed of heavy vehicles 

Measures of effectiveness are used to evaluate the operational efficiency of a particular design 

like the DLT intersection. The FHWA Traffic Analysis Toolbox has identified the following 

seven basic measures of effectiveness for vehicles:

(30)

• Travel time: average time spent by vehicles traversing a facility, including control delay, 

in seconds or minutes per vehicle 

• Speed: rate of motion (expressed in distance per unit of time) 

• Delay: additional travel time experienced by travelers at speeds less than the free-flow 

(posted) speed (expresed in seconds or minutes) 

• Queues: length of queued vehicles waiting to be served by the system (expressed in 

distance or number of vehicles) 

• Stops: number of stops experienced by the section and/or corridor (based on a minimum 

travel speed threshold) 
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• Density: number of vehicles on a street segment averaged over space (usually expressed 

in vehicles per mile or vehicles per mile per lane)

• Travel time variance: a quantification of the unexpected non-recurring delay associated 

with excess travel demand (can be expressed in several ways)

The final two measures, density and travel time variance, are less applicable to an intersection 

treatment than an uninterruped flow facility, but may still be considered during the operational 

analysis. While average speed and travel time apply to the DLT intersection much like they 

would to a conventional intersection (as long as the analysis area includes the entire 

configuration), the delay and stops performance measures must be carefully aggregated over the 

multiple signalized intersections contained within intersection. The most difficult performance 

measure to incorporate into DLT intersection analysis is queuing. This is because the short 

spacing created between the intersections within the DLT intersection may cause queue spillback 

if the signalized intersections are not properly coordinated. Individual performance measures 

such as queues, stops, and delay across multiple intersections of a typical vehicle progressed 

through the intersection provides more meaningful comparisons versus simply adding or 

averaging the performance measures from each intersection.

OPERATIONAL ANALYSIS TOOL OVERVIEW

According to FHWA’s Traffic Analysis Toolbox, several tools are available to analyze traffic 

operations at intersections, including the following:

(30)

• Planning Level Analysis (such as critical lane volume and CAP-X)

• Highway Capacity Manual (HCM)Analysis

• Microsimulation Analysis

One major factor distinguishing these three types of analysis is the time required to evaluate each 

scenario. A planning level analysis may take less than one hour to perform; an HCM analysis for 

one scenario could take two to four hours. Microsimulation requires considerably more time—

anywhere from eight to 16 hours depending on the level of calibration involved. Planning-level 

tools are useful in the initial feasibility analysis and to conduct a high-level comparison of the 

approximate number of lanes for a DLT intersection. An operational analysis using a 

deterministic method, such as the HCM, is useful to perform a more detailed peak-hour 

performance analysis, and to estimate performance measures like delay, travel time, and queue 

lengths. The operational analysis may provide insight on additional geometric design and signal 

timing details. 

The nature of a DLT intersection, especially the closely spaced and coordinated signals, can be 

difficult to evaluate in full detail in a deterministic tool and can also be evaluated with 

microsimulation.

Exhibit 6-1 provides a summary of available analysis techniques for DLT intersections. 
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Exhibit 6-1. DLT analysis techniques. 

Available Techniques

Planning Highway Capacity Manual Microscopic simulation

Available using critical lane 

analysis and CAP-X 

Difficult to perform now for motor 

vehicles; can analyze crossing 

pedestrians and bicycles. DLT-specific 

HCM procedure under development 

Can be performed for motor 

vehicles, pedestrians, and 

bicycles with most simulation 

packages

PLANNING LEVEL ANALYSIS

Planning-level tools and methods are useful in the early stages of a project when the DLT 

configuration is being considered as one of several options for an intersection improvement 

alternative. Planning-level tools and methods provide high-level analysis, typically providing no 

greater detail than volume-to-capacity (v/c) ratios and/or level of service (LOS) computations. 

Travel time, delay, queue lengths, signal timings, and specific geometric data are typically not 

inputs nor outputs of planning-level tools. In general, planning-level analysis results are useful 

for feasibility and high-level design features but are not directly tied to actual operational 

performance or operational model results.

FHWA has developed the CAP-X planning tool to conduct capacity analysis for planning of 

alternative intersections.(31) “It is a tool that can be used to evaluate selected types of innovative 

or alternative junction designs (8 intersections, 5 interchanges, and 3 roundabouts) using given 

peak hourly traffic counts.” Exhibit 6-2 is a screen capture from the spreadsheet that is 

downloadable from the Transportation Systems Institute website, A Federal Highway 

Administration Project in partnership with the Transportation Systems Institute at the University 

of Central Florida.(31)
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Exhibit 6-2. CAP-X Planning Level Tool Screen Capture.

(31) 

68

The critical lane volume methodology is a high-level analysis method that considers traffic 

volumes, number and assignment of lanes, and anticipated number of signal phases at each 

intersection. Each intersection within the DLT configuration is analyzed independently. While 

the advantage of critical lane volume is its ease of use and limited input data, this type of 

analysis does not account for some elements of traffic operations such as queues between 

closely-spaced intersections. 

• If all the signals at the DLT intersection are controlled from the same controller, then this 

form of analysis can incorporate signal coordination in the sense that some movements at 

different intersections move at the same time. 
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• The critical lane volume cannot incorporate signal progression if separate controllers are 

used and different offsets are allowed. 

HIGHWAY CAPACITY MANUAL (HCM) ANALYSIS

Analytical methods and deterministic models to establish highway capacity, vehicular delay, and 

other performance measures are required for a more detailed analysis. The Highway Capacity 

Manual, as well as Highway Capacity Software and other types of deterministic software 

available from private vendors, can be used to perform this level of analysis.(5) These tools use 

deterministic methods derived through analytical equations. An HCM procedure specifically for 

DLT intersections is under development by FHWA. The procedure will be included in an update 

of the 2010 HCM scheduled for completion in 2015. 

Operational analysis methods provide further insight into the operational effects of geometric 

design and signal timing elements of a DLT intersection compared to planning-level analysis 

methods. Advantages of the operational-level analysis approach in the HCM include the ability 

to balance operational detail with reasonable data input needs and analysis resource 

requirements. The HCM method provides more detailed output in the form of delays, travel time, 

and queue estimates than the planning-level method, while allowing for more customization and 

consideration of geometric variability and signal timing details. At the same time, its methods are 

typically applied more quickly than a more resource-intensive simulation analysis. Another key 

advantage of the HCM over simulation analysis is that the deterministic analysis framework 

offers consistency in performance estimation across analysts and interchange options. The HCM 

is generally regarded as the benchmark for operational performance estimation, and its equations 

and Level of Service (LOS) stratification form the basis of comparison with other tools. 

Disadvantages of the current HCM include a limited scope of applicable geometry and lack of

focus on network and system effects, including the interaction of the crossover intersections with 

the main crossing intersection. Other operational characteristics of DLT intersections not 

adequately handled by existing HCM methodologies include: 

• The potential for queuing to spill back from the main intersection to the crossover 

intersections, or vice versa

• The arrival and departure of vehicles between the crossover and main intersection (signal 

coordination) 

• The impact of transit stops within the boundary of the DLT intersection

• Estimation of pedestrian or bicycle level of service

The current HCM analysis models analyze each intersection independently. It is not possible to 

cumulatively analyze the travel time and delay associated with left-turning movements that are 

made through a series of intersections. Vehicles are not “tracked” through the series of 

intersections, and thus the net impact to movement delay and travel time is not readily 

comparable to conventional intersection operations. The DLT-specific procedure under 

development for the update of the 2010 HCM will include “tracking” of vehicles and net 

impacts. 
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While the HCM has limitations, as discussed above, it does provide the consistency that agencies 

need for evaluating alternatives. The HCM is an international reference manual overseen by an 

independent committee of experts in the field, and thus is often the basis for policy decisions and 

LOS thresholds for intersection selection.

When performing HCM analysis with existing procedures such as the signalized intersection 

procedure, the saturation flow rate for the left turns at the crossover intersections may need to be 

adjusted based on the turning radius (which would make the left-turn factor greater than the 

default value since this movement can occur at higher speeds than traditional left turns). While 

turning radii may increase theoretical saturation flow rates, the saturation flow rates selected

should also account for driver hesitancy based on unfamiliarity with this intersection form. 

MICROSIMULATION ANALYSIS

Microsimulation is the most detailed and data-intensive analysis that could be conducted for 

evaluating the traffic operations of a DLT intersection. There are multiple microsimulation tools, 

and some are more effective than others. Because these tools require an extensive amount of 

analyst time and data that is not always available for intersection projects, these tools needs to be 

applied consistent with the amount and type of data available, as well as specific project needs.

Advantages of microsimulation models include flexible customization and configuration of 

geometry, signal timing, and other operational parameters. However, the greatest advantage is 

that microsimulation models can output “system” measures of effectiveness for DLT 

intersections so that overall movement delay, travel times, and number of stops can be readily 

compared to conventional or other unconventional intersection designs. The ability to evaluate 

closely-spaced intersections is also a critical part of the DLT intersection. Analytical methods 

such as those contained in the current HCM can be used separately at each intersection, but 

become significantly more complicated when multiple intersections are evaluated at once. The 

DLT-specific procedure under development for the update of the 2010 HCM will provide some 

“system” measures of effectiveness.

Disadvantages of microsimulation models include the time; budget; data required for input and 

proper calibration; and knowledge of how to properly choose, set-up, run, validate, and obtain 

results. Another limitation of simulation is the need to calibrate and validate the effort, as well as 

the potential implications of failing to do so. The analyst needs to understand the many unique 

operational attributes of the DLT including saturation flow rate, speed profiles, lost time, and gap 

acceptance (for new movements such as U-turns) and know how to replicate those in simulation. 

There may also be variability in the results of DLT microsimulation evaluations performed by 

different analysts.
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CHAPTER 7— GEOMETRIC DESIGN

This chapter describes the typical DLT intersection design approach and provides guidance for 

geometric features. It requires input from the multimodal considerations (Chapter 3), safety 

assessment (Chapter 4), and traffic operational analysis (Chapters 5 and 6). The guidance in this 

chapter is intended to supplement national resources on intersections that apply basic design 

principles.

DESIGN APPROACH

Developing the geometric layout for an intersection configuration requires considering the 

relationship and interaction of safety, operations, and design. In addition, it requires 

understanding the trade-offs of the physical, environmental, or right-of-way constraints for the 

proposed DLT when local conditions preclude ideal DLT intersection layouts. As with any 

intersection form under consideration, undesirable geometry cannot necessarily be mitigated by 

signing and pavement markings. The overarching goal is to provide geometry that serves various 

users and meets their expectations. This includes clear and defined channelization that is 

supplemented with signing and pavement markings. Exhibit 7-1 highlights the characteristic 

features of a DLT intersection. 
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Exhibit 7-1. DLT characteristics.

GEOMETRIC DESIGN PARAMETERS/PRINCIPLES

The same basic geometric design parameters for a conventional intersection apply when 

developing the geometry for a DLT intersection, including: 

• Developing turn pockets (i.e., adding left- and right-turn lanes) 

• Merging right-turn bypass lane with cross street through lane or designing it as an add 

lane

• Setting the curb lines and stop bar locations at intersections using turning templates 

associated with single and/or dual turning movements 
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The DLT intersection form has unique geometric design features at the following locations: 

Main Intersection

• The objective is to provide appropriate turning paths for the displaced left turns and 

consider how they interact with the pedestrian crosswalks. 

• The vehicle paths for the displaced left turns through the main intersection will delineate

the curb lines and stop bar locations and determine the width of the overall intersection, 

as shown in Exhibit 7-2. 

Exhibit 7-2. Left-turn maneuvers. 

Crossover Intersection 

• The objective is to provide a smooth alignment for the through traffic at the crossover 

intersections and not introduce back–to-back reverse curves along the travel paths. 

• The goal is to align the left turns at the stop bar with the receiving lanes (for the displaced 

left turn pockets) to reflect desirable vehicle path alignment to minimize path overlap, as 

illustrated in Exhibit 7-3. 
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Exhibit 7-3. Crossover intersection geometry. 

• There are two ways to accommodate the geometry where the right-turn bypass lane joins 

the cross road through lanes: 

o Provide an add lane with a downstream lane merge, as shown in Exhibit 7-4 

o Signalize the movement and operate it as part of the crossover signal, as shown in 

Exhibit 7-5 
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Exhibit 7-4. Add lane with a downstream lane merge. 

Exhibit 7-5. Signalized right turn. 
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RANGE OF DLT INTERSECTION CONFIGURATIONS

While a DLT intersection can have up to four crossovers at a four-leg intersection or up to two 

crossovers at a three-leg intersection, most of the DLT intersections in the United States have 

one or two crossovers. While most existing DLT intersections contain channelized right turns, 

some have been built without channelized right turns. Channelized right turns reduce auto-toauto conflict points and provide more mobility for right turns, but they require additional rightof-way and create additional exposure for crossing movements. 

Exhibits 7-6 through 7-10 show various DLT configurations: 

• Four-legged DLT intersection with four displaced lefts

o With channelized right turns 

o Without channelized right turns 

• Four-legged DLT intersection with major street displaced lefts and channelized right 

turns 

o With channelized right turns 

o Without channelized right turns 

• Three-legged DLT intersection with major street displaced left

• Three-legged DLT intersection with minor street displaced left

A list of specific existing or planned DLT sites is shown in the Appendix. 
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Exhibit 7-6. Four-legged DLT intersection with four displaced left turns and without 

channelized right turns (West Valley City, UT).(1) 

77
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Exhibit 7-7. Four-legged DLT intersection with major street displaced left turns and 

without channelized right turns (West Valley City, UT).(1)
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Exhibit 7-8. Four-legged DLT intersection with major street displaced left turns and 

channelized right turns (Baton Rouge, LA).

(1)

79

Exhibit 7-9. Three-legged DLT intersection with major street displaced left turn (Shirley, 

NY).

(1)
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Exhibit 7-10. Three-legged DLT intersection with minor street displaced left turn

(Accokeek, MD).

(1)

OPERATIONAL EFFECTS OF GEOMETRIC DESIGN

This section addresses the operational effects of geometric design on safety performance, traffic 

operations, and quality of service for pedestrians and bicyclists. 

Crossover Intersection

The following are considerations of the crossover intersection design: 

• The traffic operations typically establishes the initial clearance time for a traffic signal.

At the crossover intersection, the intersection angle and associated intersection geometry 

refine the clearance interval for the traffic signal. As with any intersection design, the 

skew angle increases exposure for users within the conflict areas. Pedestrian crossings are 

not accommodated at the crossover intersection. 

• Entrance to the left-turn pockets for the crossover intersection is farther in advance of a 

conventional intersection, which may be unexpected for unfamiliar drivers. Appropriate 

signing that communicates with approaching drivers to position themselves in the correct 

lane needs will help drivers complete their path through the DLT intersection. 

• Carroll and Lahusen developed a deterministic model to minimizes DLT intersection 

delay based on the geometric characteristics of the intersection.

(11) The authors found that 
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for each DLT crossover, the offset length determines the maximum signal phase length 

that can be provided for the left-turn crossover. 

• NCHRP Synthesis 225, “Left-Turn Treatments at Intersections – A Synthesis of Highway 

Practice” describes several design features for DLT intersections including channelizing 

islands, overhead lane controls, and raised pavement markers for lane delineation and 

traffic flow separation.

(32)

Right-Turn Bypass Lanes 

Similar to conventional intersections, the following elements need to be considered when 

designing right-turn bypass lanes if implemented at DLT intersections: 

• The geometry at the pedestrian crossing in the 90-degree turn minimizes the speed 

difference with pedestrians at the crosswalk. 

• Stopping sight distance for the approaching motorists and sight distances for the 

pedestrians approaching the potential oncoming automobiles should be clear of 

obstructions and provide sufficient visibility for various users. 

• The location of the weaving/merging segment (where the free-flow right turn rejoins the 

through traffic exiting the intersection) in relation to the next decision point downstream 

of the intersection needs to be evaluated to minimize weaving beyond the intersection. It 

may be necessary to signalize the right turns as part of the crossover signal to eliminate a 

potential downstream weaving/merging segment.

• Driveways within the weaving/merging areas need to be avoided to minimize unexpected 

deceleration and unexpected maneuvers.

Exhibit 7-11 shows two designs for the channelized right turns. 

Exhibit 7-11. Types of channelized turns.

(22) 
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As discussed in Chapter 3, similar attention needs to be given to bicyclists at the following

conflict areas:

• The start of the right-turn lane if bicyclists are continuing through the intersection

• The free-flow right turn where bicyclists traditionally do not have bicycle lanes

• The merge point of the right turn beyond the crossover intersection on the cross street 

when merging across the bicycle lane along the cross street

• Left turns where bicycles may either function as a pedestrian or make a “Copenhagenstyle” left turn

Through Movement 

Most street facilities are typically designed according to a specific design speed. The overall goal 

is to provide tangent/smooth alignments for the through movements throughout the DLT 

configuration. A designer may consider some deflection for the through movements while 

considering the potential trade-offs such as introducing potential wrong-way movements. If 

introducing deflection for through movements, the designer needs to consider the effect the Scurves may have on travel speed (e.g., speed differential), possible vehicle overtracking their 

striped travel paths, and driver expectation of encountering non-tangent alignments. 

DESIGN GUIDANCE

This section provides guidelines by highlighting key dimensional elements when developing the 

layout of a DLT intersection. 

Right-of-Way Requirements

A DLT intersection has a larger footprint compared to conventional and other alternative 

intersections. Exhibits 7-12 and 7-13 illustrate the estimated footprint for a DLT intersection

compared to a conventional intersection. Shaded portions of the figure show where the DLT 

footprint is beyond that of a conventional intersection. Exhibit 7-12 shows a tangent alignment 

for through movements at the crossover intersections, while Exhibit 7-13 illustrates the 

undesirable deflections at the crossover intersections. 
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Exhibit 7-12. Footprint comparison of a DLT intersection with tangent through alignments 

versus a conventional intersection. 
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Exhibit 7-13. Footprint comparison of a DLT intersection with deflected through 

alignments versus a conventional intersection. 

The right-of-way footprint may affect agency decisions on whether to construct this type of 

intersection. This may be of particular focus within an urban environment or other areas where 

right-of-way may be expensive or difficult to obtain. Access to parcels located in the quadrants 

of the intersection might be restricted and U-turns are difficult to accommodate in the DLT

configuration. 

While a DLT intersection requires more right-of-way than a conventional intersection, it

typically requires less than an interchange or partial grade-separation and also provides more 

access. Median width can be reduced to mitigate the right-of-way requirements, but all median 

widths need to be sufficient to facilitate sign placement, provide pedestrian refuges, and provide 

appropriate geometry at the crossover intersections. 

Median width design guidance can be found in the AASHTO Green Book.

(4) Installing postmounted signs within the medians needs to be considered for safe and effective channelization of 

traffic. Offsets for signs should be in accordance with the MUTCD.

(6) While the median needs to 

be adequately wide to make room for left-turn lanes at the crossover (with some buffer distance 
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to achieve an angle for the crossover itself), medians exceeding this width can be 

counterproductive for the following reasons: 

• It increases walking distances for pedestrians at the main intersection. This can result in 

correspondingly longer pedestrian clearance intervals, which can be counterproductive to 

the efficient signal operation.

• It results in a wider intersection footprint, which can lead to longer yellow and all-red 

clearance times for the intersection and consequently longer cycle lengths.

Deflecting the through movements at the crossover intersections may be a way to decrease the 

right-of-way footprint in the vicinity of the crossover. The median can be narrowed using 

transition curves based on guidance from the AASHTO Green Book. Similarly, minimum 

turning radius criteria for heavy or conventional design vehicles and shoulder placement can be 

obtained from the AASHTO Green Book and applied as appropriate. 

Lane Widths

Lane widths are typically wider through turning roadways than on tangent sections. This applies 

to the DLT crossover intersections when accommodating turning paths for the design vehicle. 

The following factors can be considered when evaluating the trade-offs of providing narrow 

lanes: facility type (e.g., intersection or segment), functional classification (principal arterial), 

number of lanes, travel speed, presence of transit buses, percent of truck traffic, and area type 

(e.g., urban, rural). With this information, the overall effect of a cross-section change can be 

established. 

Design Vehicle

The design vehicle at a DLT intersection should be consistent with the design vehicle of the 

surrounding street network. The transportation professional should work with the local agencies 

to establish the appropriate design vehicle, particularly at locations where there are multilane

movements. For example, a designer can design for a 30-foot single-unit truck (SU-30) and a 

school bus to complete the dual turns side-by-side. However, a 67-foot tractor-trailer truck (WB67) would be accommodated by using both lanes (if that is a legal maneuver within the given 

jurisdiction). 

The curves associated with the left-turn movements at the crossover intersection have relatively 

large radii, and over-tracking into the adjacent lane can be addressed by adjusting the curb lines. 

Exhibit 7-14 shows side-by-side maneuvers, and Exhibit 7-15 shows semi-truck maneuvers 

through the crossover intersection. 
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Exhibit 7-14. Side-by-side maneuvers at crossover intersection.

86

Exhibit 7-15. Semi-truck maneuvers at crossover intersection. 

The design vehicle for the left turns at the main intersection will determine the stop bar locations 

and set the curb lines for the pedestrian refuge islands. Exhibit 7-16 shows the side-by-side left

turns at the main intersection, and Exhibit 7-17 shows semi-truck maneuvers through the main

intersection. 
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Exhibit 7-16. Side-by-side left turns at main intersection. 
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Exhibit 7-17. Semi-truck maneuver at main intersection.

Another consideration for designers is cross slopes (i.e., super-elevation) at the crossover 

intersection. For normal crowned facilities, the left-turning vehicle will transition from a 2-

percent slope to the outside over to a 2-percent slope to the other side of the road (total rollover 

of 4-percent) through S-curves. For trucks with unique loads this may create instability or load 

shifting. The cross section design may be coordinated with local agencies to refine the design to 

meet defined project needs. In addition to cross slope, intersections that are not situated on level 

terrain may contribute to possible rollovers. 

Crossover Intersection Spacing

The spacing between the main intersection and each upstream crossover intersection generally 

ranges from 300 to 500 feet (see Exhibit 7-18). It is not always possible to stay within these 

ranges, and there are trade-offs to be considered. For example, spacing of less than 300 feet may 

result in queue spillback and reduce the ability to clear queues through a single signal cycle. For 

an intersection spacing of more than 500 feet, it may be more difficult to coordinate DLT signal 

operations. The distance between the main intersection and the crossovers greatly affects the 

range of possible signal timing strategies that allow for coordination between movements. 

Research indicates intersection spacing influences the phase time that can be allocated to the leftturn crossover. (28). In general, a DLT intersection approach with higher left-turn demand should 

have longer spacing between the main intersection and the crossover on that approach. Higher 

design speeds also necessitate greater spacing between intersections. 
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Exhibit 7-18. Typical intersection spacing.

Pedestrians and Bicycles 

Chapter 3 provides guidelines to accommodate pedestrians and bicyclists at DLT intersections. 

As for conventional intersection design, ADA guidelines provide guidance for designing 

crosswalks, pedestrian ramps, and sidewalks, which applies to both pedestrian and shared-use 

pedestrian/bicycle paths.(17)

One unique feature for designing for bicyclists at a DLT intersection is providing a bicycle box 

in the far-side pedestrian island for bicyclists to complete a left turn through the main 

intersection. Exhibit 7-19 illustrates a layout for a modified pedestrian island to accommodate a 

bicycle box. 
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Exhibit 7-19. Bicycle box for left turn. 

Transit

As discussed in Chapter 3, transit buses can be accommodated by stopping in travel lanes or by 

providing bus pullout areas in strategic locations within the DLT configuration. Local transit 

agencies have design guidelines for bus pullouts. A typical bus pullout has 10:1 tapers in and out 

of a 40-foot long, 10-foot wide bus stop. Special consideration needs to be given to bicycle lanes 

and pedestrian amenities at bus stops. 
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CHAPTER 8— SIGNAL, SIGNING, MARKING, AND LIGHTING

This chapter presents information for designing and placing traffic control devices at DLT 

intersections, including traffic signals, signs, pavement markings, and intersection lighting. The 

unique features of the DLT, such as the width of the intersection and unconventional geometry, 

result in additional considerations with respect to signal head placement, number of signal heads, 

additional lighting and signs, and pavement markings. The guidance in this chapter supplements 

the national resources on intersection design highlighted in previous chapters, including the 

MUTCD, as well as local agency design standards and policies.

(6)

DESIGN PRINCIPLES AND APPROACH

Traffic signal design, signing, pavement marking, and lighting design at a DLT intersection can 

be different from conventional intersections, particularly related to the crossover intersections 

and the turning movement restrictions at the main intersection. For auto users, the following 

treatments need to be emphasized at DLT intersections:

• Position signal heads above the receiving lanes at the crossover intersections to provide 

guidance through the intersection 

• Provide wrong-way signage and pavement markings to warn drivers of prohibited 

movements 

• Consider overhead and post-mounted signing to guide drivers 

• Use pavement markings and overhead lane use signs to supplement other guidance 

methods 

• Provide lane extension striping to help guide motorists through the main and crossover 

intersections

• Provide appropriate lighting at conflict points (i.e., main and crossover intersection) 

within the DLT configuration to emphasize the presence of various users 

SIGNALS

Chapter 5 provides operational characteristics for potential signal phasing, timing, and 

progression. 

Working with the local agency’s maintenance department, the designer can locate the controller 

based on the following considerations: 

• Proximity to power source 

• Place equipment outside vision triangles 

• Provide maintenance vehicle access and parking
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The controller is typically located where it has the least exposure (reducing the chance it will be 

hit), or appropriate protection is provided. 

Exhibit 8-1 is a schematic of possible signal pole and mast arm locations for a DLT intersection. 

Section 4D of the MUTCD provides national guidance for traffic control signal features, 

including placement of overhead signal heads. One possible set of locations for pedestrian pushbuttons is depicted in Exhibit 8-1, and more information can be found in Section 4E.08 of the 

MUTCD.

(6) An alternative signal design is a span-wire signal that is often considered when the 

expense of a mast arm becomes relatively high. 

Exhibit 8-1. Possible signal pole and mast arm locations for a DLT intersection. 
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The DLT intersection can consist of up to five signalized intersections depending on the number 

of crossovers. The five signals can be operated either with separate controllers or with a single 

controller. Coordination of the traffic signal controllers is necessary when multiple signal 

controllers are used at a DLT intersection to control each signalized intersection separately. The 

advantages of single- and multiple-controller signal systems are described below.

Advantages of multiple controllers include: 

• If one controller fails, the other intersections of the DLT can still function 

• Programming phases and signal timing is simpler to install and maintain

• Installations require shorter wire lengths (signal conductor wire/detector wire runs to 

local controller only) 

• Easier for signal maintenance in that each cabinet will likely be placed with visibility 

provided to the signal heads it controls

Advantages of a single controller include: 

• The system requires fewer cabinets and controllers to purchase, install, and maintain

• Interconnection is not required to keep signals coordinated 

• Only one controller is required to program and maintain 

• There is a single service point for power 

• There are fewer components to fail

• Vehicle detection may be easier to configure

Signal control at a DLT intersection may be operated in a fully-actuated mode to minimize delay. 

Detectors can be installed to cover all of the crossovers, the minor street approaches, and the 

major street approaches. Detector actuation would depend on the type of operation. Exhibits 8-2 

and 8-3 show the possible detector locations and associated phases for multiple controllers and a 

single controller for a DLT intersection, respectively. 
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Exhibit 8-2. Possible detector placement locations for a DLT intersection with five separate 

controllers.
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Exhibit 8-3. Possible detector placement locations for a DLT intersection with a single 

controller. 

An angular arrow signal display as shown in Exhibit 8-4 for the left-turn traffic at the crossover

intersection could help guide motorists through the crossover intersection. 

Exhibit 8-4. Angular arrow signal display. 

Crosswalks at the channelized right-turning streets will require installing some form of 

accessible signalized treatment. This can be in the form of a RRFB, pedestrian hybrid beacon, or 

fully-signalized crossing (which can then be controlled by an adjacent controller within the DLT 

intersection so vehicular movements are coordinated). The pushbuttons for pedestrians to cross the 
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major legs of the main intersection may be located on the channelizing islands, which also serve as 

pedestrian refuges. These pushbutton locations should meet ADA guidelines and be consistent 

with Section 4E.08 of MUTCD, which also provides more information on the appropriate 

location and type of pedestrian signal heads.(6) 

SIGNING

As for conventional intersections, signing supports a motorist in making decisions at appropriate 

locations to select and navigate movements through the DLT configuration. The advance 

diverging points associated with a DLT intersection can lead to wayfinding signage becoming 

more cumbersome and costly than what is typically provided at a conventional intersection. 

Decision points occur well in advance of the main intersection and may not meet driver 

expectancy to turn left at an intersection prior to the cross street. Left-turn crossover intersections 

and driver actions must be communicated well in advance for motorists to get in the appropriate 

position when arriving at the decision point. Example signing and pavement marking plans can 

be found in the Appendix. 

New reference material is available from the TRB paper, “Evaluation of Signs and Markings for 

Partial Continuous Flow Intersection” (33). In a driver simulator study, Inman found advance 

signing of the DLT crossover intersection was critical to ensuring drivers did not miss the 

crossover completely. The study could not determine a significant difference between dual 

ground-mounted signage of the crossover and overhead-mounted signage. From the TRB paper, 

Exhibit 8-5 provides a visual perspective of the progression of overhead signage from a driver 

simulator approach of the crossover intersection. 

Exhibit 8-5. Progression of overhead signs for the DLT crossover intersection.

(33)

Exhibit 8-6 shows typical guide signage along one of the intersection approaches to be provided 

at a DLT intersection, and Exhibit 8-7 illustrates example regulatory and warning signs in the 

vicinity of the intersection. 
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Exhibit 8-6. Example guide signing along an intersection approach for a DLT intersection. 
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Exhibit 8-7. Regulatory and warning signs. 
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PAVEMENT MARKINGS

Pavement markings supplement intersection geometric design and signage. Visibility of the 

pavement marking can be influenced by weather conditions (especially snow). Part 3 in the 

MUTCD provides national guidance for consistent pavement markings throughout the United 

States.

(6) Striping approaches should be consistent with the local agency’s design guidelines.

A driver simulator study found the words “KEEP CLEAR” as pavement markings beyond the 

minor street stop bar effectively prevented stop bar overrun.(33) Section 3B.17 of the MUTCD 

provides guidance on placing these symbols.(6) Exhibit 8-8 provides a visual perspective of the 

pavement markings at the main intersection from the driver simulator approaching along the 

minor approach.(33) The study did not use “STOP HERE ON RED” signage or nearside signals, 

but suggested those messages may be equally effective treatments.

Exhibit 8-8. High treatment on minor street approach.

(33)

Exhibit 8-9 shows pavement markings along one of the intersection approaches to be provided at 

a DLT intersection. 
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Exhibit 8-9. Pavement markings along an intersection approach for a DLT intersection. 
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LIGHTING

Lighting standards and specifications outlined in AASHTO’s Roadway Lighting Design Guide, 

FHWA’s Lighting Handbook, and the Illuminating Engineering Society of North America 

(IESNA) publications including American National Standard Practice for Roadway Lighting can 

be used to determine optimal lighting for DLT intersections.

(34, 35, 36)

Based on the national lighting guidance, agencies establish street lighting design guidelines 

along their facilities that are based on the road functional classification and pedestrian conflict 

area classifications. Intersection lighting is typically 1.5 times the street lighting along the 

approaches, or the street lighting of the two crossing streets are added together to determine the 

lighting guidelines for the intersection. 

For the DLT intersection, it is desirable to light the main and crossover intersection according to 

the determined intersection light levels. Depending on the intersection spacing, the light levels 

for the road segments between the intersections may be reduced to the street segment light levels. 

If there is no lighting along the approaches, then transition lighting coming from dark into light 

and vice versa may enhance the user experience and performance. Even with sufficient lighting 

provided for the overall intersection, additional supplemental lighting could be added in the 

median to illuminate the pedestrian refuge area. 
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CHAPTER 9— CONSTRUCTION AND MAINTENANCE

Constructing a DLT intersection follows a pattern that might be similar as conventional 

intersections with the overall goal to maintain non-motorized and motorized traffic while 

providing a safe work environment. The context of the project location will inform the staging 

and sequencing of construction. DLT construction costs may be higher compared to conventional 

intersections given the more extensive street layout (more pavement and curbs) and the need for 

increased traffic control devices (potentially up to five signals). The guidance in this chapter 

supplements the national resources on construction and maintenance, including the MUTCD, as 

well as local agency design standards and policies.

CONSTRUCTION

Utah, Colorado, Missouri, Mississippi, Louisiana, Ohio, Maryland, New Jersey, and New York 

have constructed DLT intersections. These agencies could serve as resources for construction 

planning guidance. As with any new type of street construction, additional communication and 

coordination with construction contractors may streamline project implementation. 

Understanding lessons learned from agencies having developed DLT intersections may reduce 

construction delays. 

The considerations and objectives of constructing a DLT intersection are similar to those of a 

conventional intersection. In each case, primary considerations include maintaining trafficfor 

each user and protecting workers and users during construction. A DLT intersection may be

associated with reconstructing an existing intersection. If so, some considerations include local 

access, building up to four new intersections on the crossing streets, and adding new streets 

between the crossover intersections and the main intersection. When constructing a new DLT 

intersection, scenarios might include adding a new intersection to an existing street or adding the 

DLT intersection as part of a new street network. In these cases, some considerations include 

where to locate future accesses and creating frontage roads to accommodate accesses within the 

future DLT intersection influence area.

Construction Staging 

The following are potential options for constructing a DLT: 

• Close the entire intersection

• Close one cross road at a time

• Accommodate all movements/users during construction

It may be appropriate in some cases to close the entire intersection. Information gathered during 

public outreach activities can help inform construction approaches. The general public may be 

willing to accept more disruption (congestion, temporary road, or access closures) over a shorter 

construction period compared to less disruption over a longer period. In some situations, 

depending on the type of adjacent land uses, full access might need to be provided at all times. 

There may be ways to close the cross roads one at a time to simplify the movements at the main 
Displaced Left Turn Informational Guide

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intersection. There are trade-offs when selecting the most appropriate approach, and the solution 

depends on the context of the environment, such as where the project is located and the potential 

impact on the community and intersection users. In general, it may be helpful to avoid using new 

pavement for movements that will change in the final stage to avoid “training” drivers twice.

Operational analyses considering the immediate and surrounding street network can help inform 

and guide project decision making as to the approach of staging sequencing for intersection and 

street construction. Understanding stakeholder needs and the surrounding land use context 

combined with an assessment of street network operations can help inform the optimal approach 

to potential road segment closures and/or temporary lane closures during certain time periods. 

Construction sequences for converting a traditional four-leg intersection to a DLT intersection in 

Baton Rouge, LA—as well as a DLT intersection in Salt Lake City, UT—can be found in the 

Appendix. Each project used three general construction phases and accommodated various 

movements (left turn, through, and right turn for each approach) at the overall intersection. The 

three general phases used were as follows:

• Phase I – Build outside first (see Exhibit 9-1) 

o Construct right-turn bypass lanes and displaced left-turn lanes along the streets 

o Install a temporary traffic signal (if needed) at the main intersection for Phase II 

operations 

o Maintain traffic under existing signal operations at the main intersection 

Exhibit 9-1. Phase I construction. 

• Phase II – Construct major pedestrian islands (see Exhibit 9-2) 
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o Divert right turns to the newly constructed right-turn bypass lanes while 

maintaining other movements

o Construct major street left-turn lanes at the crossover intersections and the new 

traffic signals

o Construct major pedestrian islands and a new traffic signal at the main 

intersection

Exhibit 9-2. Phase II construction. 

• Phase III – Direct traffic to ultimate configuration and finish medians (see Exhibit 9-3) 

o Direct traffic to the ultimate travel pattern

o Construct medians along the major streets 

o Finalize the street lighting installation, permanent signing, and pavement

markings 
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Exhibit 9-3. Phase III construction. 

Work Zone Traffic Control 

Part 6 of the MUTCD provides guidance regarding temporary signal, signing, and pavement 

marking needs during construction and temporary street and intersection configurations.(6)

MUTCD principles and applications for conventional intersections and streets would apply to 

constructing a DLT intersection. 

A DLT intersection construction project may need more specialized work zone traffic control 

compared to conventional intersection construction, especially when informing users of the 

sequence of construction activities. The objective is to maintain the existing intersection 

operations with all the movements as long as possible at the main intersection (Phases 1 and 2). 

Installing the guide signs prior to switching the traffic to the final DLT intersection configuration 

(Phase 3) to help users navigate through the new travel pattern. Portable Changeable Message 

Signs (PCMSs) can be placed prior to the traffic switchover to inform the public in advance of 

the change; the message then needs to be adjusted to notify the users of the new pattern in place.

COSTS

The construction cost of a DLT intersection is likely to be higher than a conventional intersection 

primarily because of increased footprint and associated additional right-of-way requirements.

(25)

The costs for right-of-way and new signal control (the DLT intersection requires one to four 

additional signal-controlled intersections compared to a conventional intersection) will increase 

the cost of a DLT intersection beyond that of a conventional intersection. However, considering 

a grade separation may be an alternative option for a high volume intersection, the DLT may be 

more cost effective and produce similar operational benefits. 

Total project costs of DLT intersections depend on many project-specific factors, such as project 

context, public outreach, adjacent businesses, right-of-way, as well as the engineering and 
Displaced Left Turn Informational Guide

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contruction costs. The cost of three completed DLT intersection projects are provided below to 

give a potential range of costs. Exhibit 9-4 provides a summary of the three DLT intersections. 

Exhibit 9-4. Summary of costs associated with DLT intersections. 

Location Open to Traffic Cost Image

Airline 

Highway / 

Siegen Lane 

intersection 

Baton Rouge, 

Louisiana1 

2006 

Construction cost 

was approx. $4.4 

million (including 

$1 million for the

frontage road)2

Bangerter 

Highway / 

3500 South 

intersection

Salt Lake 

City, Utah 

2007 Total project cost 

of $7.5 million3

Route 30 / 

Summit 

Drive 

intersection 

Fenton, 

Missouri

2007 

Total construction 

cost of $4.5 

million2

1 Constructing left-turn crossovers and a frontage road; widening the existing street and channelization work (no right-of-way 

needed)

2

 Cost represents the contruction bid price of the project only

3 Cost includes all costs associated with the project (e.g., planning/environmental, engineering, and right-of-way)

MAINTENANCE 

Street maintenance of a DLT intersection is similar to a conventional intersection. However, 

there are more raised medians separating movements compared to conventional intersections. 

Repairs along any of these medians (i.e., raised islands) will likely require temporarily closing an 

adjacent lane. Closures occurring during off-peak periods may minimize traffic disruptions. This

process could follow the appropriate work zone guidelines, as for all conventional intersections. 
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Maintaining signals, signing, pavement markings, and lighting is similar to conventional 

intersections. The following DLT intersection design features may limit intersection 

maintenance, as discussed in more detail in Chapters 7 and 8: 

• Locate traffic signal controllers and signal and street lighting poles with sufficient 

horizontal clearance to reduce the potential of being hit. 

• Consider backup battery systems for the traffic signals to allow the intersection to 

continue to operate during a power outage. 

• Use agency-preferred signing material as established during the design phase of a project. 

• Place signs to provide clearance between edge-of-signs and face-of-curbs. 

• Use agency-preferred pavement marking material as established during the design phase 

of the project. Where there are “lane line extension” pavement markings through the 

intersection to guide movements (i.e. dual turning movement), place the skip striping 

according to the through movement wheel paths. 

Snow Removal 

Consistent for all types of intersections, snow removal strategies focus on systematically pushing 

snow to the outside of the street. The DLT intersection has several medians and end treatments 

that delineate curb locations (i.e., surface mounted delineators) will support snow management 

efforts. Snowplow operators will need to become familiar with the DLT configuration and 

develop a sequence for plowing the different travel paths. Through lanes are typically plowed as 

part of a corridor, and plowing the major street left-turn lanes is similar to a conventional leftturn lane. The displaced left-turn lanes will need to be plowed after the through lanes and then 

the right-turn bypass lanes will likely be plowed last.

LAW ENFORCEMENT NEEDS 

There are unique law enforcement needs at a DLT intersection. Through traffic at a DLT

operates no differently from a conventional intersection and drivers need to stay within their 

respective through lanes. However, right- and left-turning traffic—depending on the DLT 

intersection configuration—may be exposed to potential wrong-way movements as discussed 

and addressed in Chapters 4 and 8. 

Enforcement during the periods after the DLT intersections are initially opened to traffic could 

help drivers become familiar with intended operations and help reduce illegal maneuvers. As the 

novelty effect of the new intersection operations subside, the need for extra enforcement will 

likely diminish. 
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REFERENCES

1. Google Inc. Google Earth. Accessed July 2014. 

2. Rodegerdts, L. Photo Credit. 

3. Utah Department of Transportation (UDOT).CFI Guideline: A UDOT Guide to Continuous 

Flow Intersections. Salt Lake City, UT: UDOT, 2013. 

4. American Association of State Highway and Transportation Officials (AASHTO). A Policy on 

the Geometric Design of Highways and Streets. Washington, DC: AASHTO, 2011. 

5. Transportation Research Board (TRB). Highway Capacity Manual (HCM). Washington, DC: 

TRB, National Research Council (NRC), 2010. 

6. Federal Highway Administration (FHWA). Manual on Uniform Traffic Control Devices. 

Washington, DC: U.S. Department of Transportation (USDOT), 2009. 

7. AASHTO. Highway Safety Manual (HSM). Washington, DC: AASHTO, 2010. 

8. Jagannathan, R. and J.G. Bared. “Design and Operational Performance of Crossover Displaced 

Left-turn Intersections.” In Transportation Research Record 1881 (2004). 

9. Parsons, G. “The Parallel Flow Intersection: A New Two-Phase Signal Alternative,” Presented 

at Ohio Transportation Engineering Conference: Columbus, OH. 

10. Reid, J., and J. Hummer. “Travel Time Comparisons between Seven Unconventional Arterial 

Intersection Designs.” In Transportation Research Record 1751 (2001). 

11. Carroll, D., and D. Lahusen. “Operational Effects of CFI Geometrics: A Deterministic Model 

for Continuous Flow Intersections.” Presented at 92nd Annual TRB Meeting. Transportation 

Research Board, National Research Council: Washington, DC, 2013. 

12. Utah Department of Transportation (UDOT). “How to Navigate a Continuous Flow 

Intersection” webpage. http://www.udot.utah.gov/main/ 

uconowner.gf?n=1080356132239268171 

13. Ohio Department of Transportation (ODOT). IR 75 at Miamisburg-Springboro Pike/Austin 

Pike Interchange and the SR 741 at Miamisburg-Springboro Pike/Austin Pike Displaced Left 

Turn (DLT), Project frequently asked questions webpage. 

http://www.dot.state.oh.us/districts/D07/ ConstructionProjects/FAQ/Pages/default.aspx

14. Cook, M. “Continuous Flow Intersection Reduces Congestion, Increases Safety.” Transcript: 

The Ohio Department of Transportation Employee Newsletter. Ohio DOT: Columbus, OH, 2003. 

15. FHWA, USDOT FHWA Information Videos, web page. 

https://www.youtube.com/user/USDOTFHWA

16. FHWA, Safety Program Informational Brochures, web page. http://safety.fhwa.dot.gov. 

17. ADA.gov. “Information and Technical Assistance on the Americans with Disabilities Act.” 

http://www.ada.gov/2010ADAstandards_index.htm 
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18. Ray, B., et al., NCHRP 15-34A: Performance-Based Analysis of Geometric Design of 

Highways and Streets, Contractor Final Report. Washington, DC: Transportation Research 

Board of the National Academies, 2014. 

19. FHWA and AASHTO. Results of Joint AASHTO/FHWA Context Sensitive Solutions 

Strategic Planning Process, Summary Report. Raleigh, NC.: Center for Transportation and the 

Environment, North Carolina State University, 2007. 

20. Schroeder, B., et al., NCHRP Report 674: Crossing Solutions at Roundabouts and 

Channelized Turn Lanes for Pedestrians with Vision Disabilities. Washington, DC: 

Transportation Research Board of the National Academies, 2011. 

21. Brewer, M., et al., NCHRP Report 562 / TCRP Report 112: Improving Pedestrian Safety at 

Unsignalized Crossings. Washington, DC: Transportation Research Board of the National 

Academies, 2006. 

22. FHWA. Pedestrian Facilities Users Guide – Providing Safety and Mobility. USDOT 

Research, Development, and Technology Turner-Fairbank Highway Research Center: McLean, 

VA, 2002. 

23. Simmonite, B.F. and M.J. Chick. “The Development of the Displaced Right-turn

Intersection.” In Transportation Research Record 1881 (2004). 

24. Abramson, P., C. Bergren, and R. Goldblatt. Human Factors Study of the Continuous Flow 

Intersection at the Dowling College NAT Center. Dowling College (unpublished): Oakdale, NY, 

1995. 

25. FHWA. Alternative Intersection/Interchanges: Informational Report (AIIR), Report No. 

FHWA-HRT-09-060. Washington, DC: USDOT, 2010. 

26. Gluck, J., et al., NCHRP Report 420: Impacts of Access Management Techniques. 

Washington, DC: Transportation Research Board of the National Academies, 1990. 

27. Gordon, R. L., R. A. Reiss, H. Haenal, E. R. Case, R. L. French, A. Mohaddes, and R. 

Wolcott. Traffic Control Systems Handbook—Revised Edition 1996. Report FHWA-SA-95-032. 

FHWA, U.S. Department of Transportation: Washington, DC, 1996. 

28. Hutchinson, T.P. “The Control of Right-Turning Vehicles at Signal-Controlled Intersections: 

A Comment on a Suggestion by Al-Salman and Salter.” Traffic Engineering and Control, Vol. 

15. pp. 920-923. Hemming: London, 1974. 

29. Hutchinson T.P. “The Continuous Flow Intersection: The Greatest New Development in 

Traffic Engineering Since the Traffic Signal?” Road & Transport Research Vol. 3, No. 4. 

Australian Road Research Board: Vermont South, VIC, 1994. 

30. Federal Highway Administration (FHWA). Traffic Analysis Toolbox. 

http://ww.fhwa.dot.gov/publications/research/infrastructure/pavements/ltpp/04038/index.cfm 
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31. Transportation Systems Institute (TSI). Capacity Analysis for Planning of Junctions. Version 

1.2. 2011. http://tsi.cecs.ucf.edu/index.php/cap-x 

32. NCHRP Synthesis 225: Left-Turn Treatments at Intersections—A Synthesis of Highway 

Practice. Transportation Research Board, National Research Council: Washington, DC, 1996. 

33. Inman, V. “Evaluation of Signs and Markings for Partial Continuous Flow Intersection.” In 

Transportation Research Record 2138 (2010). 

34. AASHTO. Roadway Lighting Design Guide. Washington, DC: AASHTO, 2005. 

35. FHWA. Street Lighting Handbook. Washington, DC: USDOT, 1978. 

36. Illuminating Engineering Society of North America (IESNA). Recommended Practices for 

Roadway Lighting. New York, NY: IESNA, 2000 
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Appendix A CATALOG OF ALL KNOWN INSTALLATIONS IN THE 

UNITED STATES

Exhibit A-1 presents location information for all known installations of DLT intersections in the 

United States. 

Exhibit A-1. Known installations of DLT intersections in the United States

Intersection Location # Cross-overs Built Image

MD 210 at MD 228 Accokeek, MD 1 2000 

US 61/Airline Hwy at 

Siegen Ln

Baton Rouge, 

LA 2 2006 

US 61/Sgt Prentiss Dr at

US 84/US 425/Junkin Dr

Natchez, MS 1 2010 

UT 154/Bangerter Hwy 

at 

UT 173/5400 S

West Valley 

City, UT 2 2007 
Displaced Left Turn Informational Guide

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Intersection Location # Cross-overs Built Image

UT 154/Bangerter Hwy 

at 4700 S 

West Valley 

City, UT 2 2007 

UT 154/Bangerter Hwy 

at 4100 S 

West Valley 

City, UT 4 2007 

UT 154/Bangerter Hwy 

at 

US 171/3500 S 

West Valley 

City, UT 2 2007 

UT 154/Bangerter Hwy 

at 

US 171/3100 S 

West Valley 

City, UT 2 2007 
Displaced Left Turn Informational Guide

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Intersection Location # Cross-overs Built Image

William Floyd Pkwy at

Dowling College

Shirley, NY 1 1996 

NJ 168 at Nicholson Rd Haddon 

Township, NJ 1 pre1995 

MO 30 at 

Summit Rd/Gravois 

Bluffs Blvd

Fenton, MO 2 2007 

OH 741 at Austin Blvd Miami 

Township, OH 2 2010 

US 167 at Camellia Blvd Lafayette, LA 2 2011 
Displaced Left Turn Informational Guide

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Intersection Location # Cross-overs Built Image

US 34/Eisenhower Blvd 

at 

Madison Ave 

Loveland, CO 2 2011 

UT 265/University Pkwy 

at 

Sandhill Rd

Orem, UT 2 2012 

Bennion Blvd at

UT 68/Redwood Rd 

Salt Lake 

County, UT 2 2011 

UT 173/5400 S at UT 

68/Redwood Rd 

Salt Lake 

County, UT 2 2011 
Displaced Left Turn Informational Guide

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Appendix B SUPPLEMENTAL OPERATIONAL AND SAFETY 

DETAILS 

VISSIM®, a microscopic traffic simulation software, was used to gain insights into the 

operational performance of a DLT intersection in comparison to conventional intersections. Four 

intersection geometric scenarios of DLT intersections and conventional intersections were 

simulated. Exhibit B-1 shows the geometric design configurations of the cases simulated. The 

lane configurations and geometric features for the DLT intersection and conventional 

intersections on the approaches of the major road and the minor road are identical for each case. 

These four geometric cases with three major road directional splits were simulated under three 

sets of traffic volumes: low, medium, and high. The major and minor road splits were set at 50 

percent each for all simulation cases. Therefore, a total of 16 unique sets of simulation conditions 

were developed for the DLT intersection, and an equal number of unique VISSIM® simulations 

were developed for comparable conventional intersections (see Exhibit B-2). The VISSIM®

simulation network was one mile in length on the major and minor road approaches for the cases 

simulated. The base case simulations assume no pedestrian activity at the intersection. In 

addition to the use of typical VISSIM® defaults, the following constants were maintained for 

each simulation:

• Optimum fixed signal timing determined using Synchro®

• Yellow times determined using Institute of Transportation Engineers (ITE) policy 

• All-red times determined using ITE policy

• A total of 5 percent heavy vehicles on all legs

• A total of 350-foot left-turn bay lengths upstream of the displaced crossover junction 

• A total of 325-foot left-turn bay lengths downstream of the displaced crossover junction 

• A network size of 0.5 mile in each direction from the main intersection

• Single right-turn bays on the mainline

• Right-turn-on-red allowed at each signal, no left-turn-on-red allowed

• A signal at each displaced left-turn crossover 

• A 40-foot median width on mainline 

• Undivided side street 

• A 45 miles per hour (mi/h) desired speed on mainline 

• A 25 mi/h desired speed on side street
Displaced Left Turn Informational Guide

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• Saturation headway of approximately 1,900 vehicles per hour per lane (veh/h/lane) 

• No bus stops 

• Seeding time of 30 minutes for the simulations 

• Running period of 60 minutes for the simulations 

The four cases modeled are as follows: 

1. Intersection of a six-lane major road and a six-lane minor road with four corresponding 

DLTs (one on each approach) 

2. Intersection of a six-lane major road and a four-lane minor road with only two opposing 

DLTs (one on each approach of the major road)

3. Intersection of a six-lane major road and a four-lane minor T-leg with the DLTs on the 

major road

4. Intersection of a four-lane major road and a four-lane minor road with only two opposing 

DLTs (one on each approach of the major road)

Exhibit B-1. Geometric design configuration for VISSIM® simulation.

Geometric 

Design Cases

Approach Configuration

Major Road Minor Road

DLT intersection and Conventional Intersection

Through 

Lanes

LeftTurn 

Lanes

Right-Turn 

Lanes

Through 

Lanes

LeftTurn 

Lanes

RightTurn 

Lanes

A 3 2 1 3 2 1

B 3 2 1 2 1 1

C 3 2 1 2 2 1

D 2 1 1 2 1 1
Displaced Left Turn Informational Guide

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Exhibit B-2. Volumes for Geometric design configuration for VISSIM® simulation—full

DLT intersection.

Geometric Cases

Turning 

Movement 

Volume 

Set 

(veh/h)

Major 

Road 

Approach 

1 

Volume* 

(veh/h)

Major 

Road 

Approach 

2 

Volume* 

(veh/h)

Total 

Minor 

Road 

Volume** 

(veh/h)

Major Road 

Approach 1 

Volume/Total 

Major Road 

Volume 

(veh/h)

Total Minor 

Road 

Volume/Total 

Intersection 

Volume 

(veh/h)

A 

Three-lane 

major road, 

two left-turn 

lanes on 

major road, 

and three-lane 

minor road 

approaches

1 1,000 1,000 1,000 0.50 0.33

2 1,750 1,750 1,500 0.50 0.30

3 2,500 2,500 2,000 0.50 0.29

4 3,500 3,500 7,000 0.50 0.50

5 3,500 1,500 7,000 0.70 0.58

B 

Three-lane 

major road, 

two left-turn 

lanes on 

major road, 

and two-lane 

minor road 

approaches

1 750 750 500 0.50 0.25

2 1,500 1,500 1,500 0.50 0.33

3 2,750 2,750 3,500 0.50 0.39

4 3,000 3,000 4,000 0.50 0.40

5 3,000 1,286 4,000 0.70 0.48

C 

Three-lane 

major road, 

one left-turn 

lane on major 

road, and 

two-lane 

minor road 

approaches 

1 1,000 1,000 500 0.50 0.20

2 1,750 1,750 2,000 0.50 0.36

3 2,500 2,500 3,000 0.50 0.38

4 2,500 1,071 3,000 0.70 0.46

D 

Three-lane 

major road, 

two left-turn 

lanes on 

major road, 

and two-lane 

minor road 

approaches 

1 750 750 500 0.50 0.25

2 1,500 1,500 1,500 0.50 0.33

3 2,500 2,500 1,500 0.50 0.23

4 3,000 3,000 4,000 0.50 0.40

5 3,000 1,286 4,000 0.70 0.48

veh/h vehicles per hour

* A constant right-turn volume of 300 has been used and is excluded from the major road volumes shown.

** Both minor road approaches have the same volumes.

Case A Simulation

The DLT intersection simulated for this design case had three through lanes: two left-turn lanes 

and one right-turn lane per approach for all four approaches. The DLT lane before the main 

intersection had a length of 325 feet, the right-turn bay had a length of 250 feet, and the left-turn
Displaced Left Turn Informational Guide

120

bay before the separation of the displaced left-turn had a length of 350 feet. All acceleration 

lanes for right-turning vehicles were 300 feet. The median separating the opposing through lanes 

was 10 feet wide, the median separating the through lanes from the displaced left-turn lanes was 

10 feet wide, and the median separating the through lanes from the right-turn lane was 6 feet 

wide. The comparable conventional intersection had similar geometric features and dimensions 

as the DLT intersection described above on all four approaches. 

The traffic flows on the approaches of the DLT intersection were randomly generated. A large 

number of cases modeled had directional flows to replicate peak hour directional flows at 

intersections. The total cycle length for all scenarios was 70 seconds. The ranges in traffic 

volumes used for each approach by movement were as follows:

• Left-turn movement: 100–750 veh/h 

• Through traffic movement: 300–2,650 veh/h 

• Right-turn movement: 50–350 veh/h 

The results for the full DLT intersection are summarized in Exhibit B-3. In addition, a partial 

DLT intersection was also evaluated. The results are shown in Exhibit B-4. 

Exhibit B-3. Graph. Throughput and delay comparisons for geometric design case A—full

DLT intersection. 

Geometric Design Case A

3-Lane Major Rd, 2 Left-Turn Lane on Major Rd, 3 Lane Minor Rd approaches

14,500 450.0

13,500

400.0

12,500

11,500 350.0

)

10,500 300.0

ehv

)

9,500

hr

250.0

h/

8,500

(sec/

e

7,500

ay 

v (t

200.0

uhp

el

6,500 D

oug

150.0

5,500

Thr4,500 100.0

3,500

50.0

2,500

1,500 0.0

1 2 3 4 5

Turning Movement Volume Set

DLT Throughput Conventional Throughput

DLT Delay Conventional Delay
Displaced Left Turn Informational Guide

121

Exhibit B-4. Graph. Throughput and delay comparisons for partial DLT intersection 

geometric design case A. 

Geometric Design Case A

3-Lane Major Rd, 2 Left-Turn Lane on Major Rd, 3 Lane Minor Rd approaches

10,500 400.0

9,500 350.0

8,500 300.0

)eh

7,500 v

)

250.0

hrh/

6,500

(sec/

e

200.0

ay 

v (t uhp

5,500

el

D

150.0

oug4,500 Thr

100.0

3,500

50.0 2,500

1,500 0.0

1 2

Turning Movement Volume Set DLT Throughput Conventional Throughput

DLT Delay Conventional Delay

Case B Simulation

The intersection had three through lanes, two-left-turn lanes, and one right-turn lane per 

approach for the two major road approaches. The displaced left-turn lane before the main 

intersection had a length of 325 feet, the right-turn bay had a length of 275 feet, and the left-turn

bay before the separation of the displaced left-turn had a length of 350 feet. The acceleration 

lanes for the right-turning vehicles were 300 feet. The two minor road approaches were 

configured as a conventional geometric design with two through lanes: one left-turn lane, and 

one right-turn lane. For the minor road approaches, the length of the right-turn bay was 3 feet, 

and the left-turn bay was 350 ft. The median separating the opposing through lanes was 10 feet 

wide, the median separating the through lanes from the displaced left-turn lanes was 10 feet 

wide, and the median separating the through lanes from the right-turn lane was 6 feet wide. The 

comparable conventional intersection had similar geometric features and dimensions as the DLT 

intersection described above on all four approaches. 

The traffic flows on all the approaches were randomly generated. A large number of cases 

modeled had directional flows to replicate peak hour directional flows at intersections. The cycle 

length used for all scenarios was 80 seconds. 

The ranges of traffic volumes used for each approach by movement were as follows: 

• Major road left turns: 100–700 veh/h 
Displaced Left Turn Informational Guide

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• Major road through traffic: 300–2,200 veh/h 

• Major road right turns: 50–350 veh/h 

• Minor road left turns: 50–200 veh/h 

• Minor road through traffic: 50–1,200 veh/h 

• Minor road right turns: 50–250 veh/h 

The results for a full DLT intersection for case B are shown in Exhibit B-5. The results for a 

partial DLT intersection for case B are shown in Exhibit B-6. 

Exhibit B-5. Graph. Throughput and delay comparisons for geometric design case B—full 

DLT intersection. 

Geometric Design Case B

3-Lane Major Rd, 2 Left-Turn Lane on Major Rd, 2 Lane Minor Rd approaches

10,500 450.0

9,500 400.0

8,500 350.0

)

7,500 300.0

ehv

)hr6,500 250.0 h/

sec/(

ev (tu

5,500 200.0

ay el

hp

D

4,500 150.0

oug

3,500 100.0

Thr

2,500 50.0

1,500 0.0

1 2 3 4 5

Turning Movement Volume Set

DLT Throughput Conventional Throughput

DLT Delay Conventional Delay
Displaced Left Turn Informational Guide

Exhibit B-6. Graph. Throughput and delay comparisons for partial DLT intersection 

geometric design case B. 

Geometric Design Case B

2-Lane Major Rd, 1 Left-Turn Lane on Major Rd, 2 Lane Minor Rd approaches

10,500 400.0

9,500 350.0

8,500 300.0

)eh

7,500 v

)

250.0

hrh/ 6,500

(sec/

e

200.0

ay 

v (tu5,500

el

hp

D

150.0

oug4,500 Thr

100.0

3,500

50.0 2,500

1,500 0.0

1 2

Turning Movement Volume Set DLT Throughput Conventional Throughput

DLT Delay Conventional Delay

123

Case C Simulation

Case C modeled a T-intersection. There were three through lanes per direction on the major road 

with DLT lanes on one major road approach and one right-turn lane on the other major road 

approach. The minor road approach had two left-turn lanes and one right-turn lane. The DLT

lane before the main intersection had a length of 325 feet, the right-turn bay on the major road 

had a length of 300 feet, and the left-turn bay before the separation of the displaced left-turn had 

a length of 350 feet. The acceleration lane for the right-turning vehicles was 300 feet. The minor 

road approach had a conventional geometric design with two left-turn lanes and one right-turn

lane. The length of the left-turn bay on the minor approach was 350 feet. The median separating

the opposing through lanes was 10 feet wide, and the median separating the through lanes from

the right-turn lane was 6 feet wide. The geometry can be further improved if a separate 

acceleration lane is provided for the right-turning vehicles from the main road. The comparable 

conventional intersection had similar geometric features and dimensions as the DLT intersection 

described above on all three approaches. 

The traffic flows on all approaches were randomly generated. A large number of cases modeled 

had directional flows to replicate peak hour directional flows at intersections. The cycle length 

for all scenarios was 70 seconds. 

The ranges of traffic volumes used for each approach by movement were as follows: 

• Major road left turns: 50–750 veh/h 
Displaced Left Turn Informational Guide

124

• Major road through traffic: 300–2,650 veh/h 

• Major road right turns: 50–350 veh/h 

• Minor road left turns: 100–1,450 veh/h 

• Minor road right turns: 50–750 veh/h 

The results are shown in Exhibit B-7. 

 

Exhibit B-7 Graph. Throughput and delay comparisons for geometric design case C. 

Geometric Design Case C

3-Lane Major Rd, 2 Left-Turn Lane on Major Rd, 2 Left lane Minor Rd approaches

8,500 400.0

350.0 7,500

300.0

6,500

)eh

250.0 v

)

5,500

hrh/

sec/

200.0 (

ev (t

4,500

ay

u

el

150.0

hp

D

oug3,500

100.0

Thr

2,500 50.0

1,500 0.0

1 2 3 4

Turning Movement Volume Set

DLT Throughput Conventional Throughput

DLT Delay Conventional Delay

Case D Simulation

The intersection model had two through lanes, one-left-turn lane, and one right-turn lane per 

approach for the two major roads. The DLT lane before the main intersection had a length of 325 

feet; the right-turn bay had a length of 275 feet; and the left-turn bay before the separation of the 

displaced left-turn had a length of 350 feet. The acceleration lanes for the right-turning vehicles 

were 300 feet. The two minor road approaches had a conventional geometric design with two 

through lanes: one left-turn lane and one right-turn lane. For the minor road approaches, the 

length of the right-turn bay was 300 feet, and the left-turn bay was 350 feet. The median 

separating the opposing through lanes was 10 feet wide, the median separating the through lanes 

from the displaced left-turn lane was 10 feet wide, and the median separating the through lanes 

from the right-turn lane was 6 feet wide. The comparable conventional intersection had similar 
Displaced Left Turn Informational Guide

125

geometric features and dimensions as the DLT intersection described above on all four 

approaches. 

The traffic flows on all the approaches were randomly generated. A large number of cases 

modeled had directional flows to replicate peak hour directional flows at intersections. The cycle 

length used for all scenarios was 80 seconds. 

The ranges of traffic volumes used for each approach by movement were as follows: 

• Major road left turns: 100–350 veh/h 

• Major road through traffic: 300–1,500 veh/h 

• Major road right turns: 50–350 veh/h 

• Minor road left turns: 50–200 veh/h 

• Minor road through traffic: 50–1,200 veh/h 

• Minor road right turns: 50–250 veh/h 

The results are shown in Exhibit B-8. 

Exhibit B-8. Graph. Throughput and delay comparisons for geometric design case D. 

Geometric Design Case D

2-Lane Major Rd, 1 Left-Turn Lane on Major Rd, 2 Lane Minor Rd approaches

10,500 400.0

9,500 350.0

8,500 300.0

)

7,500

eh

250.0 v

)hr

6,500

h/

sec/

200.0 (

e

5,500

ay 

v (tu

el

150.0

hp

D

4,500

oug

100.0

Thr3,500

50.0 2,500

1,500 0.0

1 2 3 4 5

Turning Movement Volume Set

DLT Throughput Conventional Throughput

DLT Delay Conventional Delay
Displaced Left Turn Informational Guide

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Discussion of Simulation Results

For each of the cases modeled, the DLT intersection consistently outperformed the conventional 

intersection with respect to vehicle throughput, vehicle delay, number of stops, and queue length. 

The average vehicle delay and queue estimation models can help traffic engineers and planners 

compare the DLT intersection with other types of intersections to measure suitability of 

application, especially when traffic congestion at the intersection is a serious problem. The 

results of the operational analysis are summarized below. 

The operational improvement of the DLT intersection over the conventional intersection was 

notable even at relatively low traffic volumes, but greater benefits were achieved with the DLT 

intersection design as traffic volumes increase. The reduction in number of phases for those 

approaches with the DLT intersection significantly reduced vehicle delay and increased the 

capacity of the intersection considerably. In addition, the percent reduction in average 

intersection delay for a DLT intersection compared to a conventional intersection is shown for 

each simulated case when mainline flows are balanced as follows: 

• Case A: 48–85 percent

• Case B: 58–71 percent

• Case C: 19–90 percent

• Case D: 54–78 percent

The percent reduction in average intersection delay for a DLT intersection compared to a 

conventional intersection is shown for each simulated case when mainline flows are unbalanced

as follows: 

• Case A: 82 percent

• Case B: 70 percent

• Case C: 69 percent

• Case D: 72 percent

The percent reduction in average intersection delay for the partial DLT intersection compared to 

a conventional intersection is shown for each simulated case when mainline flows are balanced 

as follows: 

• Case A: 39 percent 

• Case B: 36 percent
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The percent reduction in average intersection delay for the partial DLT intersection compared to 

a conventional intersection is shown for each simulated case when mainline flows are 

unbalanced as follows: 

• Case A: 30 percent 

• Case B: 30 percent

The percent reduction in the average number of stops for the DLT intersection compared to a 

conventional intersection is 15–30 percent for nonsaturated traffic flows at the conventional 

intersection and 85–95 percent for saturated traffic flow conditions at the conventional 

intersection. 

The percent reduction in average intersection queue length for a DLT intersection compared to a 

conventional intersection is shown for each simulated case as follows: 

• Case A: 62–88 percent 

• Case B: 66–88 percent 

• Case C: 34–82 percent

• Case D: 64–86 percent 

The percent increase in throughput of the intersection for a DLT intersection compared to a 

conventional intersection is shown for each simulated case when mainline flows are balanced 

as follows: 

• Case A: 30 percent

• Case B: 30 percent

• Case C: 16 percent

• Case D: 30 percent

The percent increase in throughput of the intersection for a DLT intersection compared to a 

conventional intersection is shown for each simulated case when mainline flows are unbalanced 

as follows: 

• Case A: 25 percent

• Case B: 25 percent

• Case C: 12 percent

• Case D: 25 percent
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The percent increase in throughput of the intersection for the partial DLT intersection compared 

to a conventional intersection is shown for each simulated case when mainline flows are 

balanced as follows: 

• Case A: 20 percent

• Case B: 20 percent

The percent increase in throughput of the intersection for a partial DLT intersection compared to 

a conventional intersection is shown for each simulated case when mainline flows are 

unbalanced as follows: 

• Case A: 14 percent

• Case B: 10 percent

It is important to note that all cases had signal timings adjusted for pedestrian presence. In the 

absence of pedestrians, cycle lengths can be lowered resulting in average intersection delay in 

the range of 14–19 s/veh at low and medium traffic volumes for case A. 

Even with a single signal timing, the DLT intersection works effectively for all combinations of 

traffic flows (low, medium, and heavy). This is unique and can be useful for intersections that 

cannot implement multiple signal timing plans. 
Displaced Left Turn Informational Guide

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Exhibit C-1. FHWA Displaced Left Turn Intersection Brochure. 

Appendix C MARKETING AND OUTREACH MATERIALS

This appendix provides some examples of DLT Public Outreach Material Examples. 

FHWA has created alternative intersection and interchange informational videos and video case 

studies, which can be viewed on the FHWA YouTube channel 

(https://www.youtube.com/user/USDOTFHWA). 

In addition, FHWA has developed alternative intersection brochures that can be found on the 

FHWA website ( http://safety.fhwa.dot.gov). An example of the displaced left turn intersection 

brochure is shown below. 
Displaced Left Turn Informational Guide

130

Several examples from state and local agencies are provided below, although various others are 

available online for additional information and guidance. 

Educational Videos 

Several agencies have developed educational videos as part their outreach with DLTs. Examples 

weblinks are provided below for access to these videos. 

• UDOT DLT - http://www.youtube.com/watch?v=oVI3Ledw7mc

• UDOT DLT Tutorial - http://www.youtube.com/watch?v=_dB25GPPdeU 

• UDOT DLT Interactive Map - 

http://i15core.utah.gov/flash/interchange_diagrams/universityparkway/ 

• MoDOT DLT - http://www.modot.org/stlouis/links/ContinuousFlowIntersections2.htm 

• CDOT DLT - http://www.coloradodot.info/projects/us160_us550durangocfi/video.html 

Brochures and Fact Sheets

• Exhibit C-2 illustrates a fact sheet on how to navigate a DLT from the I-15 CORE project 

in Utah County, UT. 

• Exhibit C-3 illustrates a project website for the CDOT US 160/US 550 Durango DLT 

intersection in Durango, CO. 

• Exhibit C-4 illustrates a graphical illustration of the CDOT US 160/US 550 Durango 

DLT intersection in Durango, CO. 

• Exhibit C-5 illustrates a fact sheet of a DLT project with TxDOT.

• Exhibit C-6 illustrates page one of a two-page brochure for a DLT project in Illinois. 

• Exhibit C-7 illustrates page two of a two-page brochure for a DLT project in Illinois. 
Displaced Left Turn Informational Guide

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Exhibit C-2. Fact sheet on how to navigate a DLT from the I-15 CORE project in Utah 

County, UT. 
Displaced Left Turn Informational Guide

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Exhibit C-3. Project website for the CDOT US 160/US 550 Durango DLT intersection in 

Durango, CO. 

Exhibit C-4. Graphical illustration of navigating the DLT for the CDOT US 160/US 550 

Durango DLT intersection in Durango, CO.
Displaced Left Turn Informational Guide

Exhibit C-5. Fact sheet of a DLT project with TxDOT. 

133
Displaced Left Turn Informational Guide

134

Exhibit C-6. Page one of a two-page brochure for a DLT project in Illinois.

Exhibit C-7. Page two of a two-page brochure for a DLT project in Illinois.
Displaced Left Turn Informational Guide

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Appendix D SUPPLEMENTAL CONSTRUCTION AND DESIGN 

DETAILS 

This appendix presents construction sequencing options for consideration during the construction 

of DLT intersections. Work zone traffic control plans were obtained for the construction of DLT 

intersections in Louisiana and Utah and are described below. 

Sequence of Construction for DLT intersection in Baton Rouge, LA

The sequence of construction for the intersection of Airline Highway and Siegen Lane in Baton 

Rouge, LA, was obtained from the Louisiana Department of Transportation and Development 

(LA DOTD). An aerial photo of this intersection is shown in Exhibit D-1. 

Exhibit D-1. Four-legged DLT intersection with major street displaced lefts and

channelized right turns (Baton Rouge, LA).

(1)

For the purposes of this phasing sequence example, the north-south roadway will be referred to 

as the major road where left-turn crossovers were installed. The east-west roadway is the minor 

road, and the approaches were constructed in a manner similar to a conventional intersection. 

There were three phases of construction, which are discussed below. 

Phase I 

• Installation of temporary signal heads, poles, and new controllers at the main intersection, 

the minor intersection with frontage road, and the left-turn crossovers. (During phase II, 

installation of fiber optic interconnect cable for new signal system was also initiated.) 
Displaced Left Turn Informational Guide

136

• Construction of frontage roads for DLT intersection lanes, new driveways along frontage 

roads, and turnouts. 

• Construction of right-turn lanes along major roads, left-turn lanes along major roads, 

right-turn lane for frontage roads in southeast quadrant, and crossovers. 

• Placement of permanent striping on southwest frontage roads. Temporary traffic signals 

operated on a new controller.

Phase II 

• Installation of new signal poles at the main intersection, the minor intersection with a 

frontage road, and the left-turn crossovers. New signal heads on mast arms remain 

covered until placed in operation. 

• Installation of permanent signing, high mast pole lighting, temporary striping for rightturn lanes along major roads (northbound), and temporary striping for turnouts. 

• Construction of island on the service road and its temporary striping and signal heads. 

• Construction of left-turn lanes along the median edge of major roads (northbound), rightturn lanes on the minor roads (eastbound), and left-turn DLT intersection lanes on the 

major roads (northbound). 

Phase III 

• Placement of permanent signals and removal of temporary signal systems at the main

intersections. 

• Installation of temporary striping on DLT intersection lanes.

• Removal of left-turn lanes and the construction of islands in the median of major roads 

between the two left-turn crossovers. 

• Completion of islands at main intersections and remaining wearing course and permanent 

striping.

Sequence of Construction for DLT intersection in Salt Lake City, UT

Work on the DLT intersection in Salt Lake City, UT, began in March 2007, and the intersection 

opened to the public on September 16, 2007. A portion of the construction sequence was 

obtained from the Utah Department of Transportation (UDOT) Web site and is shown as 

follows: 

Winter 2007 

• Work began on the northeast and southwest corners of the intersection. 
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• The first noticeable traffic impact was the closure of right lanes in each direction near the 

intersection. 

• Crews placed construction fencing, cleared two development on adjacent sites, and 

removed a section of the sound barrier wall. 

• Some excavation and utilities work took place. 

Spring 2007 

• Excavation and utility work continued. 

• Crews began concrete work and paving. 

 Summer 2007 

• Crews completed concrete work and paving. 

• New signals were installed.

Construction work was completed at this intersection by closing it off completely and utilizing 

the existing network to detour traffic. Detour signs were placed according to typical designs and 

were located 350 ft ahead of the upstream intersection. Exhibits D-2 and D-3 illustrate the detour 

routes as well as detour signing used during the work. 
Displaced Left Turn Informational Guide

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Exhibit D-2. Illustration. Detour routes for construction of a DLT intersection in 

Salt Lake City, UT—north end.
Displaced Left Turn Informational Guide

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Exhibit D-3. Illustration. Detour routes for construction of DLT intersection in 

Salt Lake City, UT—south end.
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safety.fhwa.dot.gov

Publication Number FHWA-SA-14-068

Front and back cover photos property of Federal Highway Administration