GENERAL QUESTIONS ABOUT OUR TECHNOLOGY

Why Sequential?

Random flashing lamps provide no guidance and unnecessary warning.  Random flashing lamps are great behind the pizza shop to warn pedestrians of the sewer hole being dug in the parking lot.  When a driver approaches a work zone or incident on the road way, they are well aware of an event ahead.  What they need is guidance.  Sequential-flashing lamps scream out “Follow Me!” to approaching drivers.  Numerous academic and DOT studies reveal that drivers slow sooner and move over more effectively when presented with a sequential-flashing string of lamps.  An arrow board is great.  They are expensive.  From a distance a string of sequential-flashing lamps projects a 100-foot or 1,000-foot flashing arrow directing traffic around the point of concern.

The European Union has been using sequential lamps for two decades.  Sequential lamps are mandated at work zone entries in the U.K., as well as Italy and many other countries. Now, in the U.S., states such as Pennsylvania, Massachusetts, North Carolina, Missouri, and others have done their homework and see the safety benefits of sequential work zone lamps and sequential LED electronic flares (to replace incendiary flares).

Sequential-flashing warning lamps are described in the Federal and in every state DOT MUTCD (Manual of Uniform Traffic Control Devices- section 6F.83). The lamp is considered a warning lamp and must meet I.T.E. (Institute of Transportation Engineers) specifications for Type A warning lamp.

Technology! It simply wasn’t up to the task prior to 2005 or so.  Prior to 2005 the few deployments in the E.U. required “hard-wire” connections with power and sequencing signals being sent from lamp to lamp by a wire.  So, behind the mounting device (barrel, cone, etc.) you would see a coil of wire running to each lamp.  Recently, electronic circuity and radio-frequency or infra-red technology has provided the tools necessary to sequence lamps without wires and to do so efficiently (low battery consumption).

The different technologies? What are they and which is best?

There are three fundamental approaches to coordinating the flash signal amongst a group of lamps.

  • Infra-Red Communication: Several manufactures choose to use a beam of infra-red light to communicate, much like your television remote control unit.  Much like your T.V. remote, you must properly aim the beam at the next lamp.  And much like your T.V. remote, if your cat or spouse gets in the way of the beam, you can’t change the channel.  Such is the case with the infra-red systems.  Anything that obscures or attenuates the signal will lead to asynchrony.  Fog, snow, rain, even the sun on the horizon can wreak havoc with the signal and interrupt the sequential pattern.  In addition, in areas of wind and high-speed trucking (truck wake), the mounting device (cone, barricade, barrel, panel, etc.) will tend to “creep” or walk.  This will eventually lead to misalignment of the infra-red beam and failure to synchronize. Range between lamps is quite limited with this technology because of the energy required to transmit a strong enough light beam.  One must take into consideration that when a lamp is damaged by impact, the two closest neighbors must now communicate across twice the distance. Finally, the lamps using infra-red communication must be positioned in a straight line, not positioned more than a few feet off of the center line.
  • Master-Slave radio communication: Radio waves represent a better choice for linking nodes, but now you have lamps chattering at each other much like a crowd in a bar.  They can all hear each other.  So, how do you make sense of all this gossip?  The Master-Slave approach basically requires the operator to designate a “Master” that will do all of the talking.  The “Slave” lamps listen and receive their flash commands from the master.  There are limitations to this approach.  First, the range allowed for the Master to talk to the last slave in the line is limited by the radio range.  So, the commercially available Master-Slave systems are limited to 10 lamps or so, providing a string of several hundred feet.  Second, should the Master be damage or deplete its battery, the whole gang must go home.  No synchrony.  Sorry, games over.  Finally, each lamp must be manually programmed by the operator as number 1, number 2, number 3, etc.  Takes time and knowledge.
  • Radio “Mesh” Network:  We left the best for last.  The progression from infra-red to Master-Slave to Mesh Network is a time chart of technology development over the past 20 years.  Mesh networks are now used in your home (Wi-Fi), cellular towers, and thanks to Pi Variables, Inc., in traffic safety.  In a Mesh network, all nodes (lamps) are equal; there is no Master or Slave.  Communication is via a 2.4GHz radio signal with range of 300 meters (1,000 feet).  So the distance between any two lamps can be up to 500 feet (have to provide for a missing lamp).  The advantages of the radio Mesh network is that there is no programming.  The lamps are smart enough to establish their own sequence number as you turn them on.  They can be remotely controlled from a distance of 300 meters (1,000 feet) from ANY lamp: Not just the first lamp.  So if you can talk to lamp 39, it will send the message to all the others.  Any lamp can control the entire network, even lamp 138.  The Mesh also allows for the lamps to be “sleeping” most of the time which leads to major energy savings.  Battery life on lamps using the Mesh network typically are 4 times that of the infra-red or Master-Slave system.  And unlike infra-red systems, obstruction and weather and sun angle and straight line deployment are not an issue.  Put them in a circle, around a corner, in a building around a corner, put work trucks between them, move them with wind and truck wake, whatever, the radio signal will find its way.

Applications

Besides the work zone scenarios, sequential warning lamps can be used in a number of different applications. To list a few: Parking lots for sports stadiums, malls, school events, local city/town event, DUI checkpoints, long term police incident, crowd control, airport crosswalks, dangerous roads with curves, temporary cross walks, emergency evacuation, etc. 

Any situation where one needs to direct vehicles or pedestrians in and out of certain areas. 

Pi Variables, Inc. is a technology company always looking towards innovation.  Products in the pipeline that will use our patented Mesh technology include bicycle warning lamps, personnel lights, institutional building evacuation, and others more secret.

Specifications

Pi-Lit® technology operates in the I.S.M. 2.4Ghz frequency band. This spectrum of radio frequency is dedicated to low power devices designed for  use in the Industrial, Scientific, and Medical industries (I.S.M.).

Indeed.  All of our products utilize a “System on a Chip” (SoC) with microprocessor (computer) and radio transmitter and receiver all on a single silicon wafer.  This component is FCC compliant and our circuit design has been tested by an independent laboratory confirming that spurious signals and radio-frequency output energy fall within strict FCC guidelines, and that the device is immune from external radio-frequency “noise”.

There is a mathematical limit of 256 lamps in a string. However, strings can be grouped together in an unlimited array effectively leading to a row of lamps without limit.

Manufactured

Yes.  Now we must be careful here.  There are 6 states (we think) that are a bit of a stickler on this issue. There is only one component in our product that is made overseas.  The bare circuit board is produced by manufacturers in China.  All other components are made here in the U.S. or by U.S. companies (for example, Texas Instruments).  The only other exception is our lithium batteries, which are manufactured in China.  All of our plastic is injection molded within 20 minutes drive our our facility.  Our electronic assembly of the circuit boards is performed in our building. Assembly and testing of the product is in our facility, as is design and support (when you call us).

In 44 states we can say “Made in the U.S.A.”  However, in California, owing to the bare circuit board, we can only claim to be “Assembled in the U.S.A. or “Manufactured in the U.S.A.” but not “Made in the U.S.A.”

Research studies - Downloads

When looking through the research on sequential warning lamps provided below, please use the keyword search function in the document to scroll to their discussion on sequential warning lights

Warranty and Returns

All Pi-Lit® Sequential warning lamps have a 1-year manufactures warranty. Any defect or issue with the lamp owing to manufacturing issues will be replaced by us.

ICS SEQUENTIAL LED ROAD FLARE

Purchase

The ICS sequential LED road flares are sold in sets. They are packaged in sets of 4-flares, 6-flares, and 10-flares and are available in rechargeable and Alkaline versions.  They all come with carrying case and either lithium rechargeable batteries (with car charger + wall charger) or 4 alkaline AA batteries installed.

We have distributors world-wide.  Where we do not have a distributor close by, we can work with you directly.  Call us 24×7 to discuss color options, battery choice, and general information.  

Specifications

Pi-Lit® technology operates in the I.S.M. 2.4Ghz frequency band. This spectrum of radio frequency is dedicated to low power devices designed for  use in the Industrial, Scientific, and Medical industries (I.S.M.).

Indeed.  All of our products utilize a “System on a Chip” (SoC) with microprocessor (computer) and radio transmitter and receiver all on a single silicon wafer.  This component is FCC compliant and our circuit design has been tested by an independent laboratory confirming that spurious signals and radio-frequency output energy fall within strict FCC guidelines, and that the device is immune from external radio-frequency “noise”.

The Pi-Lit® product line operates at 6.0 volts nominal. In fact, 4-alkaline cells (whether AA or D-cell) in series generates 6.4 volts with fresh batteries.

The rechargeable systems utilize lithium polymer battery technology with nominal voltage of 7.4 volts (8.4 volts with fresh charge).

In all of our systems the “smart” electronics (micro-controllers, multiplexers, and stuff like that) operate and 3.0 volts requiring a 3.0 volt regulator to maintain a constant 3.0 volts.  The LEDs operate at a higher voltage.  Lamp brightness (intensity) is controlled through Pulse Width Modulation (PWM), where the duty cycle (percentage of on-time to off-time) during a 1-millisecond flash is varied according to the battery voltage.  As the battery depletes, the duty cycle increases to maintain constant brightness.  This approach is much more efficient because it eliminates the need for large current-limiting resistors which convert electric current flow into heat.  What appears to the onlooker as a 200 millisecond flash is really too flashes each 1 millisecond long.  Your eye cannot resolve this rapid a flash, and it all blends together.  But by varying the duty cycle the intensity can be controlled.

General Questions

There is a mathematical limit of 256 lamps in a string.  However, strings can be grouped together in an unlimited array effectively leading to a row of lamps without limit.

Nothing.  The remaining flares will continue to flash in sequence.  The missing lamp will not interrupt the sequence.

The ICS system was designed for easy and quick deployment.  First responders must deploy their warning device and get to the incident as quickly as possible.  So the ICS flare was designed with few options and less confusion.

Our construction lamps, the barricade-style and SunFlower cone-top require a bit more sophistication.  They may be on the roadway for months at a time.  Should a lamp be damaged or battery depleted, ease of replacement is mandatory. These products enjoy an “insert” mode that allows for a fresh lamp to fill a hole created by a missing lamp. 

Of course. Independent laboratory testing took 3 flares and crushed them until they “began” to crack; not pancake, but crack.

Test 1 – 30,000 pounds

Test 2 – 29,000 pounds

Test 3 – 37,000 pounds.

They may get scuffed up, or require some Simple Green or soap to clean up, but they will keep on working.

We rate the ICS flare at IP66, which means that you can hose the flare with a strong steam of water, place it in a puddle, on snow, or in the rain.  No problem.  It is impervious to dust.  BUT we do not recommend immersion into water below 1 foot.  It is not rated for sinking to the bottom of a lake.  Soon, but not yet.

Yes.  While this product has not been independently tested to be “Inherently” safe, the low voltage and conservative design virtually eliminates the likelihood of a spark.  Inherently safe testing is expensive and necessary for deployment in mines and in known volatile atmospheres.  We cannot recommend deployment in these environments.

Maintenance

Soap, water, Simple Green, damp cloth, pick your weapon.  Just rub it down with a cloth and cleaning agent and it will be good to go.

No. The lithium polymer battery is specially designed and manufactured for this product.  You will not find a replacement on the shelf at your local battery store.  If you are having difficulty with battery life, give us a call.  We can send you a replacement battery, and if you are a rocket scientist or brain surgeon, you can figure out how to install the new one.  Or speak with one of us, all rocket scientists and brain surgeons to walk you through it.  Or better yet, talk us into sending you a new flare!

No and yes.  If you are that obsessive compulsive, maybe you should come to work for us.  You can open up the case to clean the polycarbonate lens, but in so doing you will likely compromise the water seal.  If the lens is dirty on the inside, we want to see it.  Give us a call to discuss.

Downloads

Independent Laboratory Test

Warranty and Returns

We will replace your flare or road lamp within 1 year of sale for defect in manufacturing.  We, unfortunately, cannot commit to replacing the product as a result on road damage.

Sequential Barricade + "SunFlower" Cone-Top

Purchase

The Sequential Barricade and Sequential “SunFlower” Cone-Top Warning Lamps can be purchased in sets. 

We have distributors world-wide.  Where we do not have a distributor close by, we can work with you directly.  Call us 24×7 to discuss color options, battery choice, and general information.  

Specifications

The patented Pi Variables, Inc. technology uses the I.S.M. (Industrial, Scientific, Medical) 2.4GHz band. The Pi-Lit® product line is FCC compliant.  The radio “stack” or protocol is not Bluetooth, ZigBee, or Wi-Fi, but similar.

Indeed.  All of our products utilize a “System on a Chip” (SoC) with microprocessor (computer) and radio transmitter and receiver all on a single silicon wafer.  This component is FCC compliant and our circuit design has been tested by an independent laboratory confirming that spurious signals and radio-frequency output energy fall within strict FCC guidelines, and that the device is immune from external radio-frequency “noise”.

The maximum recommended deployment distance between lamps is 100 meters (330 feet). The allows for variation in radio frequency energy between lamps, multipath transmission noise (signal bouncing off trucks, vehicles, etc.), weather (rain may attenuate the signal), line-of-sight obstruction, etc.  The actual line-of-sight is closer to 300 meters (1000 feet), but remember, placement must take into account that one or two lamps may be struck by vehicles, and the two closest lamps must pass the signal down the string.  So, if a lamp is struck, the two adjacent lamps must be less than 300 (1000 feet) apart.

a) When using 4 D-cell alkaline batteries, the optimum battery life is 5 to 6 months. This operating life will be seen when flashing on one face only and nighttime only.  If the operator choses to have both sides of the lamp flashing and for 24-hours of the day, then battery life will be 3-4 months.

b) The Sunflower lamp is designed for cone-top deployment and is of lighter weight than the bolted-on barricade style lamp using D-cell batteries. The 4 AA-alkaline batteries of the Sunflower will provide 1 month of operation with single side flash and nighttime only.

General Questions

Mathematically each string is limited to 256 lamps. However, strings can be placed continuously to emulate an infinite number of lamps.  Each string of 256 lamps will merge with the next to create the visual perception of one continuous string of infinite number of lamps.

All the Pi-Lit® lamps meet and are compliant with the Institute of Transportation Engineers (I.T.E.) specifications and the Federal and State Manual of Uniform Traffic Control Devices (MUTCD) definitions. The lamps are currently self-certified crash worthy based upon the NCHRP-350 requirement of significantly similar and equal to or lighter in weight than tested devices. MASH testing will be required (or exempted at the state level) before December 31, 2019.

The Pi-Lit® Remote-Control Unit will control the string of lamps when within 300 meters of the closest lamp. The operator can be in the safety and comfort of their vehicle on an overpass, for example, that is 300 meters (1000 feet) from ANY of the lamps.  It does not have to “communicate” with lamp number 1; any lamp will do.

The Pi-Lit® product line is designed to be deployed in any weather condition. The circuit boards are coated with a protective, insulating material that prevents water or humidity from damaging the circuit.  The lens construction is designed to “breathe” which allows water vapor to escape.  Fogging of the lens owing to water vaper may occur, but will clear once the lens is dry for a few hours or placed in the sun.

The technology allows the lamps to be deplyed in any shape desired. The advantage of using radio communication is that the lamps do not need to use line of sight to communicate with one another. This allows the user to deploy them in many scenarios such as round a dangerous curve, a lane cross-over, etc. 

Maintenance

a) Periodic cleaning of the lens is recommended. Deployment on the road will result in significant dirt and grime that will diminish the light output.

b) On rare occasion, when operating on the roadway, the lamps may “hiccup”; that is, there may be some unexpected behavior. Should this occur, we recommend opening all the battery tops to disconnect the power to the lamps.  This “reboots” the computer in the lamp.  This should be done on all the lamps together.  If there is a spurious signal being transmitted by one lamp, you do not want that signal to be received by an operating lamp and retransmitted.  So, all of the lamps should be powered down before starting over.  MAKE SURE THAT THERE ARE NO LAMPS IN THE TRUCK THAT ARE FLASHING.  They will pick up the erroneous signal and pass it on.  The same will occur with the Remote-Control Unit.  Take the batteries out of the Remote-Control Unit when powering down the lamps.

You may hose it down with water and use a rag to clean the lens from dirt. Simple green is a good way to clean any dirt or grunge that wont come off by hosing the lamps down

Downloads

Warranty and Returns

All of the Pi-Lit® products are covered by a 1-year warranty. Should the lamp fail for any reason, other than road impact, we will replace it.  In most cases we will want to retrieve the defective product so that we can study it.  You will be responsible only for shipping. Please telephone for RMA (authorization)

Pi-lit Landing Zone Kit

Purchase

The ICS sequential LED road flares are sold in sets. They are packaged in sets of 4-flares, 6-flares, and 10-flares and are available in rechargeable and Alkaline versions.  They all come with carrying case and either lithium rechargeable batteries (with car charger + wall charger) or 4 alkaline AA batteries install.

We have distributors world-wide.  Where we do not have a distributor close by, we can work with you directly.  Call us 24×7 to discuss color options, battery choice, and general information.  

Specifications

General Questions

Maintenance

Downloads

Warranty and Returns

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