Upgrades: STC Crosswalk System to RRFB Configuration for Test
TEMPE, AZ - 09/02/2013 - The City of Flagstaff, AZ, a longtime user of STC
equipment, upgraded a Solar Ped-X wireless crosswalk to an RRFB
configuration. The upgrade is due in part to the city's efforts to
standardize its crosswalk locations to RRFB indication.
Flagstaff is participating in RRFB studies being conducted by the Federal
Highway Administration through Texas Transportation Institute (TTI) to
ascertain what makes the RRFB purportedly a more effective crosswalk
treatment than existing round beacons. Is it the pulse rate, lamp size, lamp
shape, lamp placement, or lamp intensity?
The engineering company doing the studies went to Flagstaff earlier this
summer to monitor motorist's response at the crosswalk using a single
12-inch amber beacon facing traffic, flashing at the standard 50-60 FPM with
a 50 per cent duty cycle. It should be noted that the original test
conditions included a 30-inch x 30-inch, W11-2 sign on what appeared to be
high intensity or diamond grade sheeting in a standard yellow color. The
original crosswalk signage did not include the W167P arrow sign pointing to
To prepare for the next round of testing, the city contacted STC to find out
if the Solar Ped-X crosswalks could be upgraded to RRFBs utilizing most of
the existing equipment. STC engineering came up with a conversion kit to
facilitate this change.
The conversion work for the controls was done in Flagstaff's traffic sign
shop by Joe Wise. The field changes were implemented by Steven Hill and
members of his sign crew at the crosswalk site.
The crosswalk features a protected pedestrian island in the middle of the
four lane road and had to be converted in sections. Unfortunately, only one
leg was completed the first day due to weather issues. Upon completion,
the WB leg of the crosswalk was outfitted with STC Type 2 RRFB indications
which feature dual 3-inch x 7-inch lamps on the leading edge and a high
intensity confirmation lamp on the end cap.
The W11-2 sign was upgraded to a 36-inch x 36-inch FYG diamond grade sign; a
W167P arrow sign was installed as well. STC noted that this adds another
variable to the prior studies done by the TTI study team and should be noted
in final analysis for the study since better signage can impact the results.
When asked about test criteria for placement of the RRFB assembly, city
personnel indicated they did not have any specific direction for the test.
Subsequently, STC and the city agreed to install the RRFB between the W11-2
and the W167P sign.
The system will run approximately five weeks prior to additional data being
taken at the location. Then the city will change the indications to 12-inch
amber LEDs again to test them as a Circular Rapid Flash Beacon (CRFB). The
12-inch DC amber beacons will operate with the RRFB flash pattern as part of
the test. The system will be configured this way for another five weeks for
the next phase of the test to allow motorists time to adapt to the change.
The city plans to revert back to the RRFB signals pending final study
results. STC DC LED lamps will work with the RRFB flash pattern and were
shown earlier this year at the Western Section ITE show and the IMSA
International Conference in Phoenix with and without rectangular masks.
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