While these two sign types can cross over, Illuminated Traffic Signs and Digital Traffic Signs aren’t necessarily the same thing. Digital Traffic Signs are traffic signs that are typically lighted with LED’s (Light Emitting Diodes) and may have a small section that shows a digital number or series of numbers and letters, such as you might see at some airports, or may be an electronic reader board with messages for oncoming motorists.

Illuminated Traffic Signs, on the other hand, may include digital traffic signs, but may simply be a sign that is lighted from below with directional lamps, giving it the appearance of being illuminated. These signs typically have a sensor that flips the switch on the lights as it gets dark and then reverses the process as daylight arrives in the morning.

As you can see, on the rail below the signs and to the outside of the service platform there are lights affixed to the rail that shine onto the reflective sign surface, making the signs highly visible at night, which is a good thing, especially if you’re new to the area or passing through.

Digital Traffic Signs are different in that they use LED’s, as mentioned earlier, and can look like this. The sign on the left is a “message center” type of sign and is programmed remotely with a new message as needed…typically something like “Road Construction starting August 1st and Never Ending…hahaha” or the like.

The sign on the right is generally programmed from a booth and will say something like “Open” or “Lot 2 Full” or similar. Obviously these signs are more expensive than your standard aluminum panel road sign, especially the message center style of sign…the one on the left, for instance, probably cost taxpayers in excess of $100K.

In the previous article I discussed standards for reflective road signs which are set nationally by the US Department of Transportation (USDOT), or by local states conforming to the USDOT’s Manual on Uniform Traffic Control Devices (MUTCD). This manual gives all the regulations for various aluminum traffic signs, but doesn’t offer regulations regarding LED signs. However, any sign used on an interstate or state highway will still need to be approved by your local authority.

There are many road sign manufacturers in the US, but only a few that manufacture the big message center LED signs. A few more make the LED panel types signs. Due to the complexity of the message center signs, many companies can sell them as distributors and do.

One other type of internally illuminated traffic sign is used almost exclusively at airports or public transportation facilities. It is the standard ballast-driven fluorescent bulb lighted sign with a decorated polycarbonate face, one or two-sided, similar to the one shown here.

Obviously, this type of sign needs to have a power source, so it’s not practical under many circumstances to use this type of sign in rural area plus they’re considerably pricier than standard aluminum traffic signs. They are also custom traffic signs and are not covered in the MUTCD, but are typically regulated by local authorities. There are many companies that manufacture these types of signs, but any of them would need to be approved by the proper certifying authority.

Today I’m discussing custom traffic signs. Just for definition sake, a custom traffic sign is a traffic sign that is non-standard. Standard signs, as discussed in the previous post, are signs like Stop signs, School Zone signs, or Speed Limit signs.

Now, for those of you who think that signs are ugly and barely a necessity, you may have a valid point as you wander around, lost, in the world you want with no signs. However, for the rest of us who like to know where the heck we are, signs are the grandest invention for finding your way ever invented!

Of course, anyone can still get lost, even with a plethora of signs showing you where to go, which is why there are gas stations. You may’ve thought they were for gassing up your rig, and that’s a little bit true, but the main reason for gas stations is to have a place to stop and ask directions (if you’re a woman) or a place to zoom past (if you’re a man) ’cause you know exactly where you’re going!

At any rate, fortunately, most of us men are now kinder and gentler, thanks to George Bush the first, and have been trained to stop and ask directions (or at least that’s what our wives think we’re doing!).

In the previous article I discussed standards for reflective road signs which are set nationally by the US Department of Transportation(USDOT), or by local states conforming to the USDOT’s Manual on Uniform Traffic Control Devices MUTCD).  This manual gives all the regulations for various aluminum traffic signs, but doesn’t address non-standard or custom traffic signs.

So, when you’re driving down the interstate, and you see a sign for the next exit that says there’s a Shell Station, a Conoco Station, and a McDonalds restaurant, who sets the standards for those signs?

Well, if you guessed your state DOT, you’d be correct…almost. Some states allow only copy on the signs, whereas others allow full color logos for the business being advertised. Businesses pay an annual fee to have their logo or name on these signs, and usually only gas stations, restaurants, and hotels/motels are eligible to be listed. Obviously, those that allow company logos like a McDonalds logo on the sign allow design standards that they don’t set, just size and material standards.

There are many other types of custom traffic signs though.  The US Postal Service has its own specs for its facilities, as do military bases. Private developments are able to customize traffic signs to their own specs as long as it’s approved by some money-sucking inspector from the county or state. HDU or wood custom traffic signs are used in some high end developments.

Material-wise, repeating standards from the MUTCD, for interstate custom traffic signs, the varying thicknesses of used are .080″ thickness, .100″ thickness, and .125″ thickness aluminum. As I also stated in the last article, the size of the sign and local environmental conditions will determine the thickness of sign material to be used, and some states require extruded aluminum for signs larger than a specific square footage.

The MUTCD specifies what types of aluminum to use on any custom traffic sign. One of the most used grades of aluminum is classification 5052-H38. The number refers to the purity and hardness of the material. All aluminum also must be alodized or anodized to prevent corrosion. Corrosion is to aluminum as rust is to steel, only faster.

Today I’m discussing reflective traffic signs or reflective road signs. As you drive down the various roads and highways, you’d certainly be lost frequently if you didn’t have signs. Back when I was a young man in my early 20′s, I spent a few winters in the Southern U.S. and was amazed at the lack of signs. Even more, I was amazed at how people knew how to get around without them.

One conversation I remember having with an old-timer went something like this…”ya’ll just travel yonda up Hwy. 357 and you’ll see a big old oak tree standin’ off by itself and there’s a road there. Ya’ll turn right on that road and drive ’til you see an old barn and ’bout half mile past you’ll take a left on a dirt road. Drive on that ’bout half a mile and you’ll see a brick house and just past that take another left and you should be there.”

Most of the time, by the way, we got lost. And that was back before cell phones, so when you were lost, sometimes you lost the whole day!

So, who sets the standards for these reflective traffic signs? In the US, the U.S. Department of Transportation’s Manual on Uniform Traffic Control Devices specifies not only the materials to be used on certain types of reflective road signs, but also determines the designs to be used, the shapes of the signs, and what reflective values are needed for various areas.

The MUTCD has over 600 various sign designs specified within its covers (although I prefer the PDF version as it’s much lighter and is always as near as my computer!). Currently the 2009 edition has been adopted by 12 of the 50 states, so some latitude is given individual states as to when to adopt the standards, although by January 15, 2012, all the states are required to adopt the standard or have equivalent state standards.

As an example of MUTCD standards, in a residential zone or school zone, “Slow Children” signs might be required to have a highly reflective “diamond grade” reflective sheeting laminated to the reflective road signs blanks because of the over-riding concern for the safety of our children.

There are varying thicknesses of reflective traffic signs material available in the US, but the most common thicknesses used are .080″ thickness, .100″ thickness, and .125″ thickness aluminum. Depending on the size of the sign and local environmental conditions, it is often left up to a local inspector as to what thickness of material will be used on various signs. A 48″ Stop sign, for instance, may be .100″ or .125″ if specified by an individual contract, whereas a 24″ Stop sign likely would be specified at .080″ in most instances.

On very large freeway signs, you probably won’t see it, but many states specify extruded aluminum sign panels locked together because of the size and wind load. Alternately, many states simply require a strong framework behind the metal panel. You’ll need to check with  the DOT in your state to learn which type is specified.

The MUTCD also specifies what types of metal can be used…one common types is 5052-H38 aluminum. This specifies the purity and hardness of the metal. It also specifies that the aluminum be either alodized or anodized to keep it from corroding.

The MUTCD also specifies categories of signs by a letter/number code, such as the S1-1 which would designate a School Zone or the R1-1 which designates a Stop sign. There are also Guide signs which start with D, E, I, or M, Regulatory signs which start with R, school zone signs that start with S, and Warning signs that start with a W. Not an exhaustive list, by the way, and not entirely accurate, but you get the idea.

Military bases often use many traffic signs as well and generally conform to MUTCD standards as well, but are not required to. They also have many custom signage needs, so there are many ways that signs are used on bases.

In the next article, I’ll discuss some variations in traffic signs that have come around in the past 20-30 years, as well as some articles regarding custom reflective aluminum signs that can be used if approved by the DOT or in private communities as well.