SAFE TRANSPORTATION FOR EVERY PEDESTRIAN CASE STUDY

Arlington County Finds the Best Spots for 

Rectangular Rapid Flashing Beacons 

Arlington, Virginia 

KEY ELEMENTS:

RRFB Implementation 

Data-Driven Evaluation

Arlington County, Virginia has developed a program 

for widespread implementation of Rectangular RapidFlashing Beacons (RRFBs) in an effort to improve 

pedestrian safety and increase driver yielding behavior 

at crosswalks throughout the County. To maximize the 

safety benefits of the RRFBs, the County has developed 

a data collection and evaluation program to inform 

future site selection and implementation. 

RRFB IMPLEMENTATION IN ARLINGTON COUNTY

RRFBs are pedestrian-actuated devices 

consisting of two rectangular yellow lightemitting diode (LED) arrays that flash 

when activated. RRFBs are combined with 

pedestrian, school, or trail crossing warning 

signs to improve safety and enhance 

conspicuity at uncontrolled pedestrian 

crossings.

Arlington County, Virginia, has a high 

level of transit accessibility because 

of its proximity to the Washington, D.C. 

metropolitan area, leading to increased 

pedestrian activity. To systemically improve 

pedestrian safety, Arlington County installed 

10 RRFBs at active pedestrian crossings 

through the end of 2017. Subsequently the 

County has planned the installation of 20 

more by the end of 2020 (figure 1). 

EVALUATING EXISTING RRFB SITES

The Arlington County Department of 

Environmental Services’ Transportation 

Engineering and Operations evaluated the 

first 10 RRFB locations, which were spread 

across the County and implemented in a 

range of settings, to optimize the placement 

of the 20 planned RRFBs. The County 

asked several key questions regarding 

both pedestrian and driver behavior at 

RRFB locations as part of their evaluation, 

including:

• Are pedestrians actuating the RRFB? 

How often?

• What are the volumes and 

characteristics of the pedestrians at the 

crossing?

• At what rate are drivers yielding to 

pedestrians at the RRFB?

• How do vehicle speeds change when 

the RRFB is flashing? 

For more information, please contact:

Dan Nabors, Design Team Supervisor, Arlington County 

Department of Environmental Science | dnabors@arlingtonva.us

Figure 1. Graphic. RRFB locations, existing and planned.

©2020 Arlington County
STEP: https://safety.fhwa.dot.gov/ped_bike/step/

Case Study: Arlington County Finds the Best Spots for Rectangular Rapid Flashing Beacons 

In addition to these items, the County Staff 

recorded data at each site including the 

number of lanes and the posted speed 

limit.

RRFB EVALUATION RESULTS 

The results across the 10 study locations 

showed that after installing the RRFBs, 

driver speeds reduced by 15 percent. 

Crossings experienced an overall increase 

of 110 percent in driver yielding (for an 

overall yielding rate of 70 percent following 

implementation). The sites also experienced 

an increase in pedestrian volumes.

Additionally, Arlington County modeled the 

average driver yielding rate as a function 

of the 85th-percentile speed (measured 

when the RRFBs were not flashing). As the 

85th-percentile speed increases, average 

driver yielding rate decreases according 

to a logistic function. The results showed 

that when the 85th-percentile speed is 

between 30 and 35 miles per hour (mph), 

a 1-mph reduction in speed corresponds 

to an 11-percent increase in average driver 

yielding rate. At 30 mph, the modeled 

yielding rate was 75 percent, but it 

deceases to 50 percent at 34 mph and to 

25 percent at 37.5 mph.

BEST PRACTICES AND RRFB SITING MATRIX

Arlington County used the results from 

the 10 RRFB study locations to support 

screening out high-speed (i.e., 40 miles 

per hour or above) roads from potential 

RRFB locations and prioritizing locations 

with the highest potential benefit. The team 

also required collecting aggregate speed 

data for the “before” condition for use 

in future evaluation and recommended 

the computation of a benefit/cost ratio. 

On an individual project level, the team 

recommended considering speed 

mitigation measures (such as speed 

feedback signs, “slow” markings, and 

speed enforcement) alongside RRFBs at 

higher speed locations to augment the 

safety effects. 

Arlington County used the evaluation results 

to update their guidelines for uncontrolled 

crosswalk treatments. Now, practitioners 

can determine appropriate treatments 

(including RRFB) based on factors including 

average daily traffic, pedestrian activity, 

posted speed limit (or 85th percentile 

speed), lane configuration, and median 

presence for a given location. 

Arlington County plans to continue 

evaluating the RRFB installations and 

collecting additional safety and operational 

data as RRFB implementation continues. 

Resources

Arlington, Virginia Department of Environmental Services, "Pedestrian Planning and Design Assessing the Effectiveness of RRFBs," https://

www.novaregion.org/DocumentCenter/View/12191/PAC-Presentation-Arlington-REGIONAL. n.d.

Smith, J., "Making Walker Safer with Rapid Flashing Beacons," https://newsroom.arlingtonva.us/release/making-walking-safer-with-rapidflash-beacons/. June 7, 2019. 

Figure 2. Photo. RRFB evaluation site on N. Quincy St. at 15th St. N.

©2020 Arlington County

When the 85th-percentile speed is 

between 30 and 35 miles per hour 

(mph), a 1-mph reduction in speed 

corresponds to an 11-percent 

increase in average 

driver yielding rate.