RRFB Research

Rectangular Rapid Flashing Beacons, or RRFBs are a new device developed to improve safety at uncontrolled marked crosswalks.  RRFBs are a pedestrian actuated warning system that alerts vehicles to people wanting to enter the crosswalk.  The high intensity rapid flashing yellow lights achieve yielding rates that previously have only been achieved with devices that have a red indication.  In addition, RRFBs are extremely cost effective to install, particularly when solar and wireless technology are used as grid connections and trenching across the roadway is avoided.  

In 2010, FHWA completed a two year study of RRFB installations at 22 locations(1).  Yielding rates before the RRFBs were between 0-26%, two years after the installation yielding rates improved to 72-96%.  The majority of locations were four lane roadways, with and without median refuge islands.  Most locations had daily vehicle volumes of 12,000 or more ADT (Average Daily Trips) and posted speed limits of 35 MPH.  


A Solution to the Traffic Engineer’s Dilemma

Traffic Engineers have for years faced a dilemma regarding crosswalk treatments - standard signs and pavement markings can not only be ineffective, they can result in an increase in crash rates.  A landmark Federal Highways Study in 2005(2) examined 1000 marked and 1000 unmarked uncontrolled crosswalks.  For locations with more than two lanes and ADTs above 12,000, crosswalks with only conventional signs and pavement markings had higher crash rates than unmarked crosswalks.  For two lane locations, marked crosswalks provided no significant improvements.

Locations like those in the study typically fall below the warrants for signalization, which leaves a gap in the tool box of what a traffic engineer can use.  For many applications, the RRFB not only fits the bill, it fits the budget.

Where are RRFBs used

RRFBs are used only at uncontrolled marked crosswalks, which are crosswalks without stop, yield, or traffic control signals.  These include crosswalks at intersections with an uncontrolled approaches or at midblock crosswalks or trail crossings.  RRFBs have also been utilized at roundabouts.  

How RRFBs are used

For each approach to the crosswalk, an RRFB is installed on the left side and the right side of the roadway at the crosswalk.  The RRFB is mounted directly below the standard crosswalk or school crosswalk warning signs, including W11-2 (Pedestrian), S1-1 (School), or W11-15 (Shared-use trail crossing), and above the diagonal downward arrow (W16-7p) plaque.

Common applications include at or near school zones and locations with higher levels of pedestrian activity.  For more information, see the FHWA Interim Approval:  

(1) "Effects of Yellow Rectangular Rapid-Flashing Beacons on Yielding at Multilane Uncontrolled Crosswalks"

(2) Safety Effects of Marked Versus Unmarked Crosswalks at Uncontrolled Locations Final Report and Recommended Guidelines 

Learn about Carmanah's new R920 Rectangular Rapid Flashing Beacon here.