http://safety.fhwa.dot.gov

SourceS

1 FHWA Techbrief: Displaced Left-Turn Intersection, 

FHWA-HRT-09-055 (Washington, DC: October 2009). 

Available at: http://www.fhwa.dot.gov/publications/research/

safety/09055/index.cfm 

An InnovATIve, proven 

soLuTIon for ImprovIng 

sAfeTy AnD mobILITy AT 

sIgnALIzeD InTersecTIons

Fenton, MO DLT Intersection 

Source: DLT Video FHWA-SA-14-021

A coST-effecTive WAy To 

MeeT coMMuNiTy NeedS 

The DLT design is flexible and can be tailored to 

meet the needs of a particular intersection and 

all of its users. Because DLT implementation can 

be full or partial, agencies and communities can 

adjust the design to balance benefits, costs, and 

impacts. When DLTs are implemented at multiple 

intersections along corridors, travel times and 

throughput are improved along the entire route. 

A DLT also can support community goals for 

pedestrians and bicycles. Provisions for walking 

and biking must be considered throughout 

the project development process, with the 

needs of pedestrians and bicycles shaping 

the overall design of the DLT accordingly. This 

includes pedestrian crossings that are accessible 

to all users , and traffic signal phases that 

accommodate both pedestrians and bicycles.

Salt Lake City, UT DLT Intersection 

Source: DLT Video FHWA-SA-14-021

1

Ibid.

coNTAcT

Jeffrey Shaw, P.E. FHWA 

Office of Safety

202.738.7793

jeffrey.shaw@dot.gov

Mark Doctor, P.E. FHWA 

Resource Center 

404.895.6210

mark.doctor@dot.gov

FHWA-SA-14-041

Updated July 2020

Shirley, NY DLT Intersection Source: DLT Video FHWA-SA-14-021
Figure 1. Depiction of separated left turns and through traffic in a DLT intersection. 

• A partial DLT with crossovers on only

select intersection approaches increased

throughput by about 20 percent.

• DLTs significantly reduced delay – by 30-40

percent for the partial DLT and 50-80 percent

for the full DLT.2

DLT intersections have been constructed in several 

states, including Louisiana, Maryland, Missouri, New 

York, and Utah. More DLTs are being considered in 

these and other states.

The DLT is best-suited to intersections with 

moderate to high overall traffic volumes, and 

especially to those with very high or unbalanced 

left turn volumes. It can be a competitive 

alternative to a full, grade-separated interchange.

SAfeTy ANd operATioNAl 

BeNefiTS

Improving safety and mobility are important goals 

of every road agency. The DLT advances both of 

these goals through unopposed left turns and 

simpler traffic signal phases. A traffic signal at 

a DLT can use as few as two phases, meaning 

shorter and more efficient cycles.

The DLT design reduces the total number and 

overall severity of vehicle-to-vehicle conflict 

points. Conflict points decrease from 32 to 28 

when a conventional intersection is converted to 

a full DLT.1

 The unopposed left turns at the main 

intersection eliminate the need for drivers to 

judge the speed and gaps of oncoming traffic, 

greatly simplifying the maneuver.

A study by FHWA using traffic models 

to compare performance between 

DLT intersections and equivalent 

conventional signalized intersections 

showed the following:

• A full DLT with crossovers on

all intersection approaches

increased throughput by about 30

percent.

Motorists, pedestrians, and bicyclists face 

greater mobility challenges and safety risks 

at intersections as traffic volumes grow and 

congestion worsens. Agencies need safer, more 

balanced designs that keep people moving. 

Innovative intersection designs represent a 

solution, and are being built more often because 

they can deliver more for less.

WhAT iS A diSplAced lefT 

TurN iNTerSecTioN?

The Displaced Left Turn (DLT) intersection 

implements unopposed left turns at 

intersections by moving traffic over to the other 

side of the road in advance, as illustrated in 

Figure 1. Traffic crosses opposing through lanes 

at a separate signalized intersection before the 

main intersection, entering a parallel left turn 

lane separated from opposing lanes. At the main 

intersection, left turning and through traffic 

move simultaneously, increasing efficiency and 

safety by reducing conflict. Traffic signals at the 

advance crossovers are coordinated with the 

main intersection to minimize stops.

A DLT is sometimes referred

to as a Continuous Flow 

Intersection (CFI)