FAQs

Q1. Is a K or Ka-band radar device on the IACP’s approved list important?

A1. Ka-band requirement combined with IACP listing requirement reduces choices to, perhaps, 1 manufacturer in the US. Every sign manufacturer in the U.S. but one uses one of two guns; Decatur Electronics SI-II or Kustom Signals' DRU unit. Both of these are K-band units designed expressly for this type of application but both of no interest to the folks compiling the IACP list. Unless the client expects to write tickets and issue fines for offenses using these signs (not recommended either) this requirement is competition limiting, over-reaching and costly. These types of signs are described by both the NHTSA and the MUTCD as "advisory" signs and not "traffic control" devices negating any reason to over-engineer such a product.

Q2. The sign we are considering has what they call a 7-Segment display. They say these are as good as your full graphic characters? Are they really?

A2. The seven segment style design is simply antiquated. Moreover, independent studies have shown that cognitive recognition of seven segment vs. full graphic characters is significantly slower and at X-whatever mph, time is of the essence. This independent study also demonstrates that our 18" graphic display outperformed one competitor's 25" character sign in live on-road testing. The most recent revision of the California MUTCD specifically recommends use of full graphic characters over 7 segments when selecting a speed feedback sign.

Q3. What do you think of user adjustable amperage (sic. Intensity) for different applications?

A3. There are no different applications; every time you place one of these signs in public you are trying to slow people down. Adding this variable is only going to exasperate anyone looking for consistent results. Now, automatic adjustment to ambient light conditions is critical as you need full intensity in full sun and need to moderate brightness for night conditions.

Q4. One supplier is touting the advantage of a rather limited (30 degrees) included angle of readability. RU2 talks about 160+ degrees of legibility. What gives?

A4. This 30 degree thing is like a religious question; you either believe or you don’t. But once you do the trig, it smells more like a red herring. Here is our take:

IF you calculate the distance from the center of the sign face, accepting that the near lane driver is something like 14 ft. lateral off-set and intersect the driver with the 30 included angle the sign goes dark for him about 52 ft. down range. If you open that up to 160 included angle the sign goes dark about 2½ ft. down range –let’s call it a 50 ft. delta. 50 feet at 35 mph is covered in less than 1 second, at 25 mph in 1.36 seconds. What we are suggesting here is that the entire argument is…an excuse, not a feature.

Q5. Regarding the radar device, they talk about programming the sensor for distance and inclusion/exclusion of approaching/receding targets. Huh?

A5. Let’s take these things separately. Being able to adjust the sensor for distance isn’t an inherently bad idea. Our original response was to make the sensor independently adjustable to the sign face in both X and Y axis so that the sensor paints an “area of interest” much like pointing a flashlight while keeping the sign’s “best face forward”. This is in contrast to being able to make the sensor “stupider” but still pointing at the moose on the horizon. RU2 recently added user adjustable sensitivity to our signs in 5 increments for the greatest degree of flexibility in set up.

Oddly enough there are few suppliers out there still providing base equipment without single directional (approach only) radar, making it instead an option that you have to pay for. Our gun can pick up 8 discrete targets, determine approach/recede and, sort by signal strength. And we don’t charge extra, so there! We specifically filter for the strongest, oncoming target –only. Under what circumstances would you want to display receding targets other than to confuse everyone looking at the sign?

Q6. Suspensions: Leaf Spring vs. Torsion Bar; what’s the difference and should I care?

A6. At the loaded weights we are talking about (1000 pounds is a trifle in the trailer world) the biggest difference between the two technologies is a bit nicer ride (torsion) versus bullet proof (leaf). You may have to replace a torsion bar suspension over the life of the trailer; you probably won’t have to replace a leaf spring. We went with bullet proof leaf springs; some of our competitors went torsion claiming a gentler ride for their (tender) electronics. So, should you care? Nope.

Q7. What’s the deal about wet paint versus powder coat and can you do either right or wrong?

A7. Without a lot of hot air (get it?), a properly applied powder coat finish will outperform any wet paint finish. Today, you will find wet paint finishes only on the cheapest of equipment and we don’t mean just radar trailers. And sometimes that’s alright if the life expectancy of the piece of equipment is short by its nature (think: arrow boards).

We employ a 2 part powder coat system, first applying what is known as “high zinc” epoxy primer which gets a partial bake, then a polyester application over that. Epoxies alone are very chemical resistant, great adhesion and impact resistance but typically have very little resistance to UV rays and will “chalk” very fast leaving a dull, smudgy, unattractive finish. Polyesters by themselves don’t have the chemical resistance of epoxies but are specifically formulated for outdoor equipment and have strong UV resistance, staying bright and shiny for years. Dirty metal, sharp edges and under or over curing are the enemies of a good powder coat. Great prep and attention to process detail prevent that.

Q8. While we’re on paint, are any coatings really “graffiti proof”?

A8. No, not really. What we have been told by the manufacturer we use (Rohm & Haas) is that the only Graffiti-proof coating is a secondary clear overcoat which, unfortunately, due to a difference in coefficient of expansion, will craze (crack) and trap dirt, eventually causing the “object of concern” to look like crap anyway. And it’s expensive. We can do it. We don’t recommend it.

Q9. Batteries, batteries, batteries…what should I know about batteries?

A9. Quite a bit, yet nothing…how Zen! There are really two questions here; one, what is the difference in battery technology and two, how long can I go with your equipment between charges?

Our battery universe is divided along the lines of battery construction. Currently, there are three common lead-acid battery technologies: Flooded, Gel, and AGM.
Flooded or Wet Cells are the most common lead-acid battery-type in use today. They offer the most size and design options and are built for many different uses. Typically, the cells can be accessed via small ~1/2" holes in the top casing of the battery so the user can replenish any electrolyte the battery vented while charging the battery.

The plastic container used for flooded cells will have one or more cells molded into it. Each cell will feature a grid of lead plates along with an electrolyte based on sulphuric acid. Since the grid is not supported except at the edges, flooded lead-acid batteries are mechanically the weakest batteries. They are also the cheapest.

Gel Cells use a thickening agent like fumed silica to immobilize the electrolyte. Thus, if the battery container cracks or is breached, the cell will continue to function. Furthermore, the thickening agent prevents stratification by preventing the movement of electrolyte.

As Gel cells are sealed and cannot be re-filled with electrolyte, controlling the rate of charge is very important or the battery will be ruined in short order. Furthermore, gel cells use slightly lower charging voltages than flooded cells and thus the set-points for charging equipment have to be adjusted.
Absorbed Glass Mat (AGM) batteries are the latest step in the evolution of lead-acid batteries. Instead of using a gel, an AGM uses a fiberglass like separator to hold the electrolyte in place. The physical bond between the separator fibers, the lead plates, and the container make AGMs spill-proof and the most vibration and impact resistant lead-acid batteries available today. Even better, AGMs use almost the same voltage set-points as flooded cells and thus can be used as drop-in replacements for flooded cells. Basically, an AGM can do anything a Gel-cell can, only better. However, since they are also sealed, charging has to be controlled carefully or they too can be ruined in short order.

Gel and Absorbed Glass Mat batteries are relative newcomers but are rapidly gaining acceptance. There are some very compelling reasons to use VRLAs (valve regulated lead acid):

•Gel and Absorbed Glass Mat (AGM) batteries can dispense charge at a higher rate than flooded cells due to their lower Peukerts exponent. Deep-cycle Flooded Cells cannot deliver more than 25% of their rated amp-hour capacity in amps without plummeting Available Capacity.
•Virtually no gassing under normal operating conditions: Unlike flooded cells, gel cells and AGMs are hermetically sealed and operate under pressure to recombine the oxygen and hydrogen produced during the charge process back into water.
•For every additional 15 degrees of heat over 77 deg F, lead acid battery life (regardless of type) is cut in half (batteries self-destruct with time, you can only slow that process).
•VRLAs can operate in any orientation (although you may lose some capacity that way) and even if a container is broken, a VRLA will not leak. Proper (heavy duty) battery restraints are a must, regardless of battery type.
•Gel cells and AGMs require no maintenance once the charging system has been properly set up. No equalization charges (usually), no electrolyte to replenish, no specific gravity checks, no additional safety gear to carry in order to protect yourself. If you want to be anal retentive about VRLAs you can load test them. However, proper charge control and protection is much more important with VRLAs because once fried it is impossible to revive them.
•The higher charge efficiency of AGMs allows you to recharge with less energy: Flooded cells convert 15-20% of the electrical energy into heat instead of potential power. Gel-cells lose 10-16% but AGMs as little as 4%. The higher charge efficiency of AGMs can contribute to significant savings when it comes to the use of expensive renewable energy sources (wind generators, solar panels, etc.) as your charging system can be 15% smaller (or just charge faster).
•While flooded cells lose up to 1% per day due to self-discharge, VRLAs lose 1-3% per month.
•High vibration resistance: The construction of AGMs allows them to be used in environments where other batteries would literally fall to pieces. This is another reason why AGMs see broad use in the aviation and the RV industry.
RU2 uses gel cells on its Fast-6000 and Fast-600 models, AGM on everything else. Enough about that!

The other issue, probably more germane, is field autonomy or, how long can I deploy the trailer between charging. Everything else being even, the two primary factors in play are current draw of the gun and sign and duty cycle. Overall efficiency of the design can vary all over. RU2’s primary 12”and 18”character signs draw 18 Watts peak, another manufacturer may be at 25W, another even higher. The difference between 18 and 25 is a 28% advantage right there. We typically see 7 to 10 days of service from a fully charged trailers and under proper circumstances, many of our solar assisted trailers are virtually field autonomous requiring quarterly of semi-annual charges to “top them off”. Amp hour figures are by themselves meaningless.

Q10. The "SPEED LIMT" sign size on your Fast-375 isn't dimensionally to MUTCD standards. Are we going to be in violation if we use it?

A10. Regarding the “non-standard”sizing of the Fast-375 sign overlay, it stems primarily from the origin of the underlying electronics. That is, early on we decided to make the best “full graphic”character sign we could at standard 18”character size for placement on a radar trailer. This was long enough ago that the pole-mount concept hadn’t been marketed by anyone yet. As we were not looking to reproduce or adapt to anyone’s standard sheet metal we started out with a blank sheet of paper and ended up with a terrific sign with a 40”wide case.

Designing the typical R2-1 Speed Limit Sign overlay for the nearest standard size (36”x 48”) we maintained the 1 to 1.33 aspect ratio and ended up with a 41”x 54.5”plaque. Non-standard perhaps, but conforming.

An interesting thing comes up in all of this and is particularly poignant if one was examining “standards”for a reason “Not To Do Something”; The 18”character specification (or 12”for that matter) defies all R2-1 standards. The standard character heights are 8”, 10”, 14”and, 16”. The 16”character is for the 48”x 60”sign, recommended for posted limits of 55MPH or greater. Strictly by these standards everyone in this business is wrong. An 18”character on a 36”x 48”(or larger) sign should look really stupid (and non-conforming) except…that it doesn’t. And our characters look really good in our plaque.

By the way, in looking for 3rd party blessings, the most recent California MUTCD issued this: “Guidance: To the degree practical, numerals for displaying approach speeds should be similar font and size as numerals on the corresponding Speed Limit (R2-1) sign” which we naturally take as a ringing endorsement of our “full graphic characters” (vs. antiquated 7 segment).

Q11. We are in the process of writing specifications for the purchase of a radar speed trailer. One of our engineers is concerned with NCHRP 350 compliance as we intend to use it on an Interstate. What's the scoop?

A11. Trailers of this type are exempt from NCHRP - 350 Crash Testing. Even though they are a Type IV device, the FHWA has recognized that in order for them to meet NCHRP-350 requirements - they would need an Impact attenuator that would be bigger than the Trailers. Additionally in an attempt to make Changeable Message Signs (Full Size Trailers) NCHRP-350 compliant (in past testing), the "Roll Ahead" factor encountered after impact was unpredictable. In other words - you couldn't tell if the impact attenuator made the unit safer - more often than not the Trailer would still roll forward further than an unprotected trailer and often would wind up crossing adjacent lanes of traffic.

It was decided that trailer mounted equipment would be compromised by an attenuator in that it would be heavier, take up a larger footprint on the roadway, and present an operational problem in its field deployment (make it more complex to setup and remove from the roadway - resulting in Longer exposure in live traffic to the user).

After checking accident statistics (Nationwide) the FHWA could not find a number of reported accidents of Vehicles running into the trailer mounted equipment (Other than a few anecdotal occurrences of Drunk Drivers hitting trailers).

Their final decision said that the practices currently being used (putting the trailers behind guardrail and barrier walls where practical,or in the clear way - described as 30 feet off of the traveled portion of the highway, or if need required that the unit be placed on a shoulder, then the unit should have at least 1-2 feet of clearance to the live lane and it should have temporary traffic control devices - that is orange drums or cones used to form a taper in front of the trailer to highlight the placement of the trailer on a shoulder.

REF http://safety.fhwa.dot.gov/roadway_dept/road_hardware/nchrp_350/catg4.htm

Q12. I am...

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Trailer

Size: Some things to consider while looking at the trailer size (height, weight and length) is visibility around the trailer when it is setup and when it is in tow.

Weight: The weight of the trailer can predict whether or not it is feasible to tow with a squad car or not. Sometimes a trailer may be so heavy, it can only be safely towed with a truck. Also, moving the trailer around by hand may be a problem if it weights too much. If a trailer is too light, it could fall victim to high winds during bad weather.

Materials of Construction: The base of a trailer is primarily made from steel of various shapes and thickness. The enclosure that houses the components are usually made of steel or fiberglass. A popular material for building trailer bases is 1 ½ to 2 inch square tubing 1/16 to 1/8 inch think. In comparison, 1 1/2 square tubing 1/16 inch thick would be average duty, and a 2 inch square tubing 1/8 inch thick would be very heavy duty.

Paint: Good paint is important in order to get many years of good service from your radar trailer and withstand the rugged use. Powder coating is one method of achieving this goal. Powder coating is a thick baked on paint that is very durable.

Axle: A heavy duty axle with a weight capacity rating stamped on it to ensure quality is important. When the trailer is being moved, the axle and springs take most of the abuse so they should be of good quality. Grease fittings on the hubs will make routine greasing an easy task which will ensure longer bearing life. Tires: Tire size is important depending on the trailer usage and size. If the unit has a lot of highway travel or the trailer is heavy, at least a 13 inch tire is needed. This is about the size of a small car tire. A typical 13 inch tire size will be written BR78-13. If the trailer is light enough, then an 8 to 10 inch tire will be sufficient. The smaller the tire, the less the cost of the unit. An 8 or 10 inch tire is the same size that is used on a small boat or jet ski trailer. These sizes are typically written 4.80/4.00-8.

Light Hookup: The connector that plugs in from your tow vehicle to the unit for lights needs to be considered. There are three commonly found connections: four prong flat plugs, four prong round plugs, and five prong round plugs. The type your vehicles are equipped with should be specified to the radar trailer manufacturer. This will take out the frustration when you receive your trailer, and aren’t able to hook it up properly to your vehicle.

Hitch: There are two common ball sizes, 1 7/8 and 2 inch. Again, this should be outlined in your radar trailer specifications to the manufacturer.

Theft: There are various methods of theft deterrents. Everything from locking a bar through the wheels, to simply locking a leveling jack and alarm systems are available. The things to remember when reviewing these systems are how effective the method is and how cumbersome and time consuming is it to the person setting up the unit. If someone really wants to steal the trailer, they will find a way, the theft deterrents are only there to make it more difficult for them to steal.

Lifting Jacks: Lifting jacks are used to both stabilize the unit and compensate for uneven terrain when setting up the trailer. The most widely used type is the jack screw. The jack screw can be permanently mounted or swing down. The jack screw type has a handle on the top that turns to lower and raise the jack. One disadvantage to this type of jack is that the handle has to be turned many times in order to lower and raise the jack. If you multiply this times three or four jacks, setup becomes a very cumbersome and time consuming process.
Another type of jack is a swing down jack which requires a handle to pry down a slotted skid one notch at a time. This is a much faster jack but the operator needs a strong arm and lowering the jack is more difficult.
One very fast and convenient jack is an electric actuated jack. This jack can be extended 24 inches in about 30 seconds. When reviewing different jacks keep in mind the personnel and situation in which the unit will be setup.

Display

Size: When evaluating the displays size, what is important is the actual character size. For example, an 18 inch display should mean 18 inches from the top of the number to the bottom of the number. Display size requirements depend on the normal usage and budget for the unit. For higher speed area usage, 45 miles per hour and up, the sign should be at least an 18 inch or larger display. In residential areas and school zones, a smaller 12 inch and larger display would be sufficient. Method of Display: There are two ways to make numbers for radar signs. One method uses light and the other is by flipping segments electro-mechanically. The preferred method is light. This is done using a technology that has only in the last ten years become cost effective and efficient. The light is generated from high intensity LED’s (light emitting diodes). LED’s are not light bulbs, but are diodes which are very power efficient and by focusing with a lens creates a very bright light. Unlike light bulbs, LED’s can be turned on and off many times with extremely low percentage of failure. Flipping segments electro-mechanically is not very power efficient and has moving parts which creates frequent failures.

Display Arrangements: There are primarily two arrangements for creating number characters. One is a seven segment display which creates a squared off number using a different combination of lines, much like a calculator. The other method uses several rows and columns of dots. This array of dots is known as full matrix display. A full matrix display is capable of creating rounded characters that are more pleasing to the eye and easier to recognize at a glance.

Night and Day Viewing: In order to see LED’s during the day, they need to be at full brightness. At night, the LED’s at full intensity can be blinding to on coming traffic. The intensity can be controlled using ambient light sensing and adjusting the intensity of the LED’s accordingly. This is commonly referred to as automatic intensity control.

Protective Cover: The display needs to be protected by a transparent window. The most commonly used form of protection is Lexan, which is very durable and will not be penetrated by most objects, including bottles, rocks and in some cases even bullets. The texture of the outside surface should not be shinny, as the sunlight or headlights create a glare, preventing the numbers from being easily seen.

Radar Unit

Band: One of the higher frequency band radar units should be used, K band or higher. K Band has many advantages including it’s accuracy, and is widely used by manufacturers.

Single Directional Radar: Another important feature to consider is a single directional radar unit. Single directional radar will only display the speed of on coming vehicles, ignoring traffic traveling away from the unit. This prevents on coming motorist from getting mixed signals as they approach the sign.

Certified Radar Units: It is important that the radar unit has the proper FCC certification. Not all radar units are certified, and some states have different regulations as to what is a “certified”radar unit. If a certified radar unit is required, it is important to communicate this to your sign manufacturer.

Power System

Charging: Unless a unit is equipped with a solar panel, the radar unit will require periodic recharging. This could range from charging every day to every 30 days depending on the usage and power supply. The radar sign usage will have to be taken into consideration when shopping for a sign. It only takes a few batteries to run a unit for a few days, but it takes many batteries to run for 30 days. The battery will need replacing every three years or so, make sure the unit is easily serviceable and consider the cost of replacement batteries.

Batteries: Battery technology has come a long way in the last few years, and there are some very good batteries available. Deep cycle dry or gel cell batteries are efficient and emit no hydrogen gas during recharging. These batteries are higher in initial cost, but have a longer life expectancy. Another type of battery is a deep cycle lead acid battery that also has a layer of oil in the battery. This is a very efficient battery and emits a negligible amount of hydrogen gas during recharging. This battery is lower in cost, and like the dry and gel cell batteries, is less likely to have corrosion on the terminals due to the presence of acid.

Solar Power: The use of a solar panel or panels is a good way to make a unit self-sustaining. Some things to consider are the cost and effectiveness of solar power. The effectiveness depends upon the power required as compared to the power supplied by the solar panel, and the amount of sunlight available in your region. Consider how long the unit needs to run without sunlight to determine if solar power is a cost effective power supply.

 

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Posted: Aug. 18th, 2010

RU2 is excited to announce the release of our latest version of Traffic Count traffic data analysis software package. Please visit our Data Collectiion page for more details.

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