By now, you have likely read our MUTCD article regarding methods to increase traffic sign conspicuity. Many of those methods are relatively low cost measures that, used sparingly, can be effective at areas of concern along your roadways. A more aggressive (and more costly) method that some jurisdictions have expressed interest in are rectangular rapid-flashing beacons (RRFBs).
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The Delaware Manual on Uniform Traffic Control Devices (MUTCD) contains many options for making signs more conspicuous (see Figure 2A-1).[1] The Federal Highway Administration (FHWA) issued a 2018 Interim Approval memorandum that also permits the use of RRFBs at uncontrolled, marked crosswalks, under the provisions of the MUTCD and the Interim Approval memorandum. In other words, if you wish to consider RRFBs, care must be given to do so under the right conditions. Additional FHWA information and frequently asked questions are also posted in their safety brief.
FHWA approved a request from the Delaware Department of Transportation (DelDOT) to deploy RRFBs and in doing so, required DelDOT (aside from complying with the conditions of the Interim Approval) to maintain a list of all RRFB installation locations in Delaware, including those installed by local agencies, so even on locally maintained streets, coordination with DelDOT Traffic is required to ensure that everyone is in compliance with the Interim Approval. They are more than willing to help with tips they’ve learned from the currently 22 installations shown on their tracking poster.
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Do they work? Are they helpful? The Crash Modification Factors Clearinghouse suggests a 47.4% reduction in crashes where they have been studied, but because the data are still small, the CMF is considered weak in quality for now. That said, the supporting research by Zegeer, et al. (NCHRP Research Report 841) was promising. Still, the report concludes that “the CMF for RRFB was based on a very limited sample, and hence should be used with caution.” DelDOT’s own data collection has shown highly mixed results, as shown on their tracking poster. There are many variables at play with any crossing and an RRFB should not be viewed as a sure thing, particularly given their cost.
DelDOT’s experience with solar and Wi-Fi have been poor, and their hardwired installations have ranged from $30,000 to $55,000 per crossing (in addition to any upgrade requirements for the Americans with Disabilities Act, ADA).
If RRFBs (or other alterations) are planned, consideration must also be made for ADA compliance. Any alteration triggers a legal requirement to provide accessibility to the full crossing for all pedestrians. Physical ramp and turning space elements must be in compliance, but accommodations for blind, low vision, and deaf pedestrians must also be incorporated.
As with any project to improve safety for motorists, pedestrians, and cyclists, a comprehensive and sometimes, phased, approach is best. Before the expense of an RRFB is undertaken, a close look at signage at the crossing, advance warnings, the condition of pavement markings, and barriers to good sight conditions is a good first step. It may be that an upgraded signage and pavement marking program will provide positive results that will be necessary even if a RRFB is later added.
The Delaware T2/LTAP Center’s Municipal Engineering Circuit Rider is intended to provide technical assistance and training to local agencies and so if you have pedestrian safety questions or other transportation issues, contact Matt Carter at matheu@udel.edu or (302) 831-7236.
[1] Delaware MUTCD, Section 2A.15
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