Comprehensive RRFB Specs for Safety Compliance

Have you heard about the importance of versatility and standardization in RRFBs?

In today’s blog, the Availed Technologies team outline why this is so crucial, its many benefits, and a real-life example of versatility and standardization done right.

Let’s dive in.

What Are RRFBs?

RRFBs are a unique traffic control device designed specifically to improve pedestrian safety at uncontrolled marked crosswalks. Uncontrolled crosswalks come in many different shapes and sizes from one-way or two-way roadways, from two to four lanes, and with or without median islands, curb bulb outs or extensions, etc.

On the other hand, uncontrolled crosswalks can be located at intersections where the major legs are through lanes or at mid-block locations such as school crossings or trail crossings. Other locations include roundabouts and bicycle corridors.

Lastly, crosswalk locations can sometimes have sightline issues due to curves or other features.

What is Versatility and Standardization in RRFB-Related Product Design?

With over 25 years of combined experience in the Solar LED industry (and, more specifically, solar LED for traffic safety), our team has both the knowledge and the skillset to deliver products that out-perform the competition year after year.

How do we achieve this?

By utilizing both versatility and standardization.

Versatility refers to how adept a product is at being used in a range of configurations that stem from the crosswalk and roadway design.

Standardization in this discussion is defined as the extent to which versatility can be accomplished with a single model.

For example, a key requirement for configuring RRFBs at the crosswalk is to have lightbars visible to oncoming vehicles on both the left and right hand side of the roadway. This requirement, coupled with the wide range of crosswalk configurations results in the need for the RRFB device to be versatile. Consider these scenarios:

Two way, two lane roadway. In this common configuration there are two back-to-back lightbars on each side of the crosswalk.
Two way, four lane roadway with median. In this configuration there are typically single sided lightbar systems on the curb sides and either one back-to-back system or two single sided systems on the median. The systems on the median may or may not have push buttons.
Crosswalks at a roundabout. In this application each crosswalk is for one-way traffic, therefore single sided lightbars are typically used.

As demonstrated here, RRFBs can include either one or two lightbars and be with or without a push button. In some cases, such as when sightlines require it, the location of the lightbars will be different than where the push button should be located. This scenario may utilize a system that consists of only the solar engine and the push button, without any lightbars.

In other cases, such as when RRFBs are installed in advance of the crosswalk with the Ahead sign, the system would consist of one lightbar and no push button.

In all cases with RRFBs, there is a wireless connection between systems so that when a push button is activated on one system the other system(s) at the crosswalk flash. Ideally the wireless connection between systems is automatic and requires no field configuration. Regardless of how many systems are used, all will turn on and off in a synchronized manner when the push button on any one of the systems is activated.

In the event that there are multiple crosswalks in proximity to one another there needs to be a means to avoid a push button actuation at one crosswalk activating lightbars at another crosswalk. This is referred to as crosstalk and can be easily addressed by a field adjustable dial on the solar engine controller for channel selection.

Learn More About Versatility and Standardization for RRFBs Today

The MUTCD 11th Edition, chapter 4L requires that RRFBs be on both the left-hand and right-hand side of the roadway for each approach. This frames the crosswalk for drivers and is one of the reasons the system is so effective. As we have seen, it does demand versatility in the system to allow for a range of installation configurations.

To simplify the ordering, inventory, and installation logistics an RRFB system should be able to have two, one, or no lightbars and either be connected to a push button or not. In other words, it should be both standardized and versatile.

At Availed Technologies, all of our products are created and sold with both versatility and standardization in mind.

By prioritizing these two product design factors, we ensure that our RRFBs fit a wide range of crosswalk configurations and are easy and fast to install.

To learn more about how to utilize our best-in-class RRFBs, or if you have questions about how to implement RRFBs in your particular situation contact our team today.

Image source: https://www.pexels.com/photo/landscape-photograph-of-skies-912364/

How much do you know about the power of solar RRFB systems?

In today’s blog, the team here at Availed Technologies outline common FAQs surrounding solar-powered RRFB systems: namely what the common array-to-load (ALR) variables are and what to keep in mind when maximizing power consumption.

Firstly, What Makes the ALR so Crucial?

The fundamentals for ensuring that the power of solar RRFB systems will be reliable year-round hinge on having a system where, on a daily basis, the power generated is greater than the power consumed. In the solar field this is known as the array-to-load ratio, or ALR.

Many of the variables for determining the ALR are intuitive, while others are less so. The following variables are considered the most common:

Time of Year, Latitude, and Historical Weather

A given system will have a much greater ALR installed in the sun-belt than in the Pacific Northwest. Time of year, latitude, and historical weather are all variables that are captured in solar insolation data available from NREL (the National Renewable Energy Laboratory.)

Industry best practices are to ensure the ALR of a system is a minimum of 1.2:1. To calculate this, the solar insolation value (measured as equivalent sun hours) for the month that has the lowest solar insolation for the year (typically December) is used.

Trees and Buildings

One often overlooked variable is shading from trees and buildings. Google’s Street View provides an excellent tool for determining the shade derating of a particular location, and it is important that this is factored into the calculation.

Why? Because more shade, of course, equals less daily power!

‘Under-the-Hood’ Variables

Also frequently overlooked are the ‘under-the-hood’ variables of solar RRFB systems themselves.

On the power generation side of the equation, this involves the solar panel and charging system that work together to deliver power to the batteries. Monocrystalline solar panels provide greater efficiency over polycrystalline solar panels; this difference is greatest during marginal charging conditions where, for an RRFB application, this is often when charging is most critical.

Similarly, Maximum Power Point Tracking (MPPT) charge controller technology provides greater efficiency over PWM (Pulse Width Modulation, particularly during lower light conditions where power generation can be so crucial.

The variables discussed so far are on the power generation side of the equation. On the power consumption side there are often very significant differences between different manufacturers’ systems and the technologies that are used.

Solar RRFB System Power Consumption

Before outlining the power consumption variables of solar RRFB systems, it should be noted that there are some inherent ‘buffers’ that make RRFBs particularly well-suited for solar power.

During the winter months where solar insolation is at its lowest, there is typically lower pedestrian activity… particularly during inclement weather. In addition, with shorter daylight hours comes more activations occurring in darkness when the system runs at a lower intensity, as dimming is required by the MUTCD for RRFBs and works to mitigate the disability glare that occurs if the light intensity is too bright.

Now, onto key solar RRFB system power consumption variables:

LED Efficiency

LED efficiency is a key variable in power consumption of an RRFB system. LEDs have been described as the ‘enabling technology’ for solar traffic devices and the gains seen throughout the years have been a game changer.

The landscape keeps changing and today there are ultra-efficient premium LEDs that, while cost-prohibitive for many applications, provide energy savings for devices like solar RRFBs that are significant.

The light intensity specification for RRFB LED indications is SAE J595 Class I which requires a relatively narrow beam pattern, much narrower than the ITE specification for LED Traffic Signal Modules. Compared to school zone flashers and 24-hour flashers that utilize these modules RRFBs require far less power which makes the device particularly well suited for solar power.

At the same time, in part due to the directional beam pattern combined with the irregular flash pattern, the RRFB is far more effective than traditional flashing beacons for a pedestrian activated warning system at uncontrolled crosswalks.

Wireless Technology

Another determining factor of power consumption is around the wireless technology used.

When one RRFB system is activated by the pedestrian push button all other systems commence activation simultaneously through being connected wirelessly. A wireless system designed for this specific application will consume a fraction of the power of a system designed for more general ITS applications.

Similarly, a controller that is designed specifically for the RRFB application will consume far less power than a controller designed for multiple applications. A well-designed controller will manage all the functions of the system with microchip level components on a single printed circuit board assembly. These functions include charging, powering the LEDs, field adjustments such as flash duration, and wireless connectivity between systems.

In short, an inefficient system can consume nearly four times the power compared to a highly efficient system. The Availed AV-400 RRFB, with a 20W solar panel and 14Ah battery capacity, will have a greater operating capacity than a less efficient system with a 60W solar panel and 50Ah battery capacity.

Energy Storage

Energy storage is the other key factor that needs to be considered and properly specified. The purpose of including batteries in an RRFB system is two fold: to enable operation during dark conditions when there is no charging, and to enable the system to operate through extreme weather conditions where over a 24 hour period the power generated could be less than the power consumed (ie when the ALR ratio is less than 1).

Consider a scenario when there are heavy overcast skies day after day in the winter time when daylight is already greatly reduced. In these conditions, charging will still occur with systems that have efficient charging technology, however the system could run an energy deficit where more power is consumed than generated during a 24 hour period. Sufficient battery capacity will ensure that the system will continue to operate throughout these conditions.

Industry best practices are for a system to have an autonomy of 5-to-10 days. A system with a high ALR will maintain reliable operation even with a lower autonomy due to the system’s ability to maintain charging in challenging conditions.

Start Utilizing the Power of Solar RRFB Systems Today

Given the multitude of variables involved in both the power generation and power consumption, the best way to evaluate an RRFB is with a Solar Performance Report that provides the array-to-load (ALR) and autonomy calculations.

Need help getting started harnessing the power of solar RRFB systems? Reach out to Availed Technologies today.

The Importance of Versatility and Standardization in RRFBs