Even though digital and illuminated route signs can cross over, they 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 a digital traffic sign could 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 illuminated traffic signs typically have a sensor that flips the switch on the lights as it gets dark and then reverses the process on the illuminated traffic signs as daylight arrives in the morning.
If you happen to see an illuminated sign, there are lights affixed that shine onto the reflective sign surface, making the signs into illuminated traffic signs that are highly visible at night, which is a good thing, especially if you’re new to an area or passing through.
Digital traffic signs are a bit more different just in the sense that they employ light emitting diodes to lighten their signs up. They’re exactly like a “message center” type of sign that is programmed remotely with a new message as needed… typically something like “Road Construction starting and Never Ending…” or the like.
They are usually programmed from a booth and will say something like “Open” or “Close” or similar. Obviously these digital traffic signs are more expensive than your standard aluminum panel road sign, especially the message center style of signage.
The standards for reflective road signs 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 both digital traffic signs and illuminated traffic signs. However, any street signage used on an interstate or state highway will still need to be approved by the state DOT or USDOT.
There are many road sign manufacturers in the US, but only a few that manufacture the big message center LED digital traffic signs. A few more make the panel-type LED digital traffic signs. Due to the complexity of the digital traffic signs/message center signs, however, many companies can sell them as distributors.
One other type of internally illuminated traffic sign is used almost exclusively at airports or public transportation facilities. These are a standard ballast-driven, fluorescent bulb, internally illuminated traffic signs with a decorated polycarbonate face, one or double-faced.
Obviously, these internally illuminated traffic signs need to have a power source, so it’s not practical under many circumstances to use this type of sign in rural areas, plus these internally illuminated traffic signs are considerably pricier than standard aluminum traffic signs. They are also custom illuminated 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 internally illuminated traffic signs, but all of them still need to be approved by the proper certifying authority.