Question: What is the difference between Standard Reflective (Engineer Grade or Type I), and High Intensity (Type III) and Diamond Grade (Type XI) reflective sign material?

Engineer Grade

Engineer Grade Reflective Sheeting typically meets ASTM D4956 Type 1 standards and is an enclosed film or lens using glass beads or prismatic optical technology.

This material is specified for use on non-critical street and road signs such as parking signs or wayfinding signs. It has less reflectivity than the other types mentioned in the original question.

Question:  What is Reflective Sheeting?

Reflective sheeting is the sheeting used to create reflective road signs, traffic signs, street signs, and highway signs.

Basically, reflective sheeting is laminated to aluminum sign blanks of various sizes and shapes, then printed with whatever copy is needed, and you have a reflective traffic sign.

Different Reflective Sheet Grading

Reflective sheeting comes in various grades, the most common being “Engineer Grade,” “Hi-Intensity Prismatic”, and “Diamond Grade.” The USDOT requires diamond grade for most interstate 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 such signposts! Even more, I was amazed at how people knew how to get around without them.

One conversation I remember having with a Southern gentleman, an old-timer in Mississippi, went something like this…”ya’ll just travel yonda up Hwy. 357 and you’ll see a big old oak tree standin’