I don't design highway signs for a living any more, but I used to. I still go to garage sales, though. That puts me in a position to speak knowledgeably about signs, their design, and their use.
By the way, I much prefer signing to signage. Just personal preferage.
Lets start with how NOT to make a sign.
Don't do this.
You start with how long it takes to read a sign. Drivers need time to read signs, and how much time they need depends on what the sign says. Try writing down what you want the sign to say, and reading it out loud. Don't hurry, not everyone can read as fast as you can. Time how long it takes. If you don't have a stopwatch, try reading it ten times (try not to laugh, it screws up your timing) and divide.
If it takes longer than about three seconds, go back and rewrite the text. Highway signs are designed to be read at a glance, which is why they have so little information on them. More information takes longer to read and distracts the driver from his job - yakking on his cell phone and fiddling with the CD player.
How much time drivers actually have to read a sign is determined by:
If traffic is traveling at 30 mph - 45 feet per second - and it takes three seconds to read the sign, you need to make it visible from 45 x 3 = 135 feet away. At 50 feet per inch of letter height, that's 2.7 inches. I'd round it up to three because I'm lazy.
See why ½" letters won't work? You can only read them from 25 feet away, or ½ second at 30 mph.
Not all the text needs to be this big - just the part you want them to read first. Make the important information big, and the less important information small. (Notice I said "less important" and not "unimportant" - if it's unimportant, it shouldn't be on the sign.)
If you make your sign on printer, DON'T use a fancy font. Use something very simple and easy to read. The Federal Highway Administration has established a standard font called "E-Modified", which is perfect if you can find it, but any wide sans-serif font with a heavy stroke is good. You want a font where the M is about as wide as it is tall, and the stroke width is about 20% of the height. "Arial Black" and "Swis721 Blk BT" are standard Windows fonts that work well.
If you work by hand, lay out lines to keep your text straight. Lower case letters are two-thirds the height of the upper case letters. The space between lines should be ¾ the height of the lower-case letters.
Pencil in the letters first, keeping an eye on your stroke width (one-fifth of letter height), to make sure the text fits and is centered nicely. The spaces between words should be the width of the upper-case letter A, and between sentences should be the same as the letter height. Erase and adjust until it looks good.
Lastly, paint in the letters.
A road where there is a lot of low-speed traffic is best.
Choose a location where drivers have time to react to the sign. At a red light, they've got all the time in the world to read the sign and decide to turn. But will they have time when the light is green and they're not stopping? Put the sign a bit in advance of the intersection, but not so far that it's not clear where to turn.
If the sign is in advance of the intersection, place another at the intersection. The latter can have less important information replaced with an arrow to indicate the turn. If you do this, you need to somehow relate the signs to each other, either by color or by legend.
If the turn leads them directly to the site, great. If not, you need follow-up signs to indicate later turns. Don't lead them into the countryside and expect them to know where they're going.
Paper sucks, but sometimes is the only reasonable material. It's cheap and goes through a printer.
Use thick cardboard - if you use corrogated cardboard, make sure the corrugations run horizontally, not vertically, or the sign will fold up in the wind. Use plywood for permanent signs.
The background should be some light color. White is best for reading, but fluorescent colors catch the eye better. The text should be black. Whatever you use, it should be waterproof. Shiny is bad, as it produces glare.
Nothing is more annoying than trying to read a sign that is wrapped around a pole so only the middle third is visible. Mount flat, or nearly flat, whenever possible.
If using paper, attach it at the corners to keep them from bending inward and blocking the sign. This limits its use to surfaces without much curvature. If you must mount on a curved surface, such as a light pole, try to arrange the text into two or three columns so it can be read without walking back and forth to see around the edges.
Cardboard is preferable for mounting on poles because it can keep itself flat. Attach it at the center top and center bottom. Make sure the corrugations run horizontally so the wind won't fold it up.
Don't put the sign up before you need it, and take it down as soon as possible after you are done. If you leave it up forever, you're just training drivers to ignore signs.
Why put the date on a sign if you aren't going to leave it up when it doesn't apply? For driver confidence - it's a way of saying "No, you won't be wasting your time following this sign." Besides, you might forget and leave the sign up.
© 2005 W. E. Johns