LPIs reduce conflicts 

between pedestrians 

and vehicles.

LPIs improve visibility 

of pedestrians in the 

crosswalk. 

FEATURES:

• Increased likelihood of 

driver yielding.

• Enhanced safety 

for slower moving 

pedestrians. 

COMPLIMENTARY 

TREATMENTS:

• Right Turn on Red (RTOR) 

Restrictions.

• Accessible Pedestrian 

Signals.

• Parallel Vehicular Green 

Extension Interval.2

Leading Pedestrian Intervals (LPIs) are low-cost adjustments 

to signal timing to increase pedestrian safety at signalized 

intersections. An LPI gives pedestrians a typical 3- to 7-second 

head start before vehicles in the parallel direction are given 

the green signal indication. LPIs can help reduce conflicts 

between pedestrians and left- or right- turning vehicles. The 

LPI works to position the pedestrian within the crosswalk 

thereby decreasing the likelihood of a conflict or crash with 

a left- or right-turning vehicle ahead of the turning traffic. 

Agencies will often consider restricting Right Turns on Red 

(RTOR) in association with LPIs to better control for conflicts 

with right-turning vehicles.

The Manual on Uniform Traffic Control Devices (MUTCD) offers 

guidance on signal timing when LPI is used. The MUTCD says 

an LPI “should be at least 3 seconds in duration and should 

be timed to allow pedestrians to cross at least one lane of 

traffic or, in the case of a large corner radius, to travel far 

enough for pedestrians to establish their position before the 

turning traffic is released.” Using Accessible Pedestrian Signals 

(APS) with LPI provides indications for persons with disabilities. 

MUTCD guidance also offers considerations for accessible 

pedestrian signals when LPIs are used.2

LPIs can 

reduce 

pedestrian 

crashes by1

13%

!

Leading Pedestrian 

Interval (LPI) 

SAFE TRANSPORTATION 

FOR EVERY PEDESTRIAN

COUNTERMEASURE TECH SHEET

October 2019 | FHWA-SA-19-040
References

1

 Goughnour, E., Carter, D., Lyon, C., Persaud, B., Lan, B., Chun, P., ... Signor, K. (2018). Safety Evaluation of Protected Left Turn Phasing and Leading Pedestrian Intervals on 

Pedestrian Safety, Federal Highway Administration, Report No. FHWA-HRT-18-044. Washington, D.C.

2

 Federal Highway Administration. (2009). Part 4, Chapter 4E Manual on Uniform Traffic Control Devices. Federal Highway Administration. Washington, D.C.

3

 Dittberner, R., & Vu, N. (2017). How Long Is Your LPI?: Balancing Pedestrian Comfort and Traffic Impacts with an Elongated Leading Pedestrian Interval. ITE Journal. 

Washington, D.C. 

LPI LENGTH 

Researchers have developed formulas 

to help agencies calculate a desirable 

duration of an LPI, calculating the minimum 

time required for pedestrians to cross the first 

travel lane or halfway across one direction 

of travel. Streets with wide or multiple lanes 

may result in pedestrian crossing phases 

that are longer than the concurrent vehicle 

phase. This situation may lead the agency 

to consider elongated LPIs to reduce 

conflicts with left-turning vehicles.3

COST

LPI installation requires reprogramming the 

traffic signal to accommodate the advance 

pedestrian interval. In rare cases, agencies 

may need to upgrade signal controllers. 

The cost associated with LPI can range 

from $200 (controller setting changes only) 

to $1200 each (pedestrian/vehicle study, 

retiming analyses, incorporating the formers 

setting changes).1 

SELECTING SITES FOR LPI

Several cities across the U.S. have decided 

to install LPIs across systems of signalized 

intersections to improve pedestrian safety. 

Agencies prioritize the intersections where 

they install LPIs to maximize limited resources 

and after considering several common 

factors:

• Crash history. A review of 3 or more years 

of crash data for intersections with multiple 

crashes or a history of severe injury/fatal 

crashes are often a priority. Cities also use 

information from observed conflicts to 

supplement crash data. 

• Pedestrian crossing volumes. Cities may 

look for pedestrian volumes exceeding 

traditional pedestrian signal warrants when 

considering LPIs. The estimated exposure 

(product of pedestrian and turning traffic 

volumes) may be another consideration.

• Vulnerable populations. Agencies often 

prioritize LPIs where school-aged children or 

older adults are expected to cross. These 

pedestrians may enter the crosswalk more 

slowly than other pedestrians. 

• One-Way Streets or at T-intersections. 

Where left-turning vehicles aren’t typically 

expected to yield to oncoming vehicles, 

LPIs may be useful to increase yielding to 

pedestrians in the crosswalk. 

• Intersection Visibility. LPIs may be 

prioritized where the visibility of a crosswalk 

is limited or restricted. General examples 

are geometry, location of stopped vehicles, 

vegetation, and streetside features. 

STEP: https://safety.fhwa.dot.gov/ped_bike/step/ 

Leading Pedestrian Interval (LPI)

Source: FHWA