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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.