A large, bright road sign directs highway drivers to an exit.

Road Sign Uniformity: What Matters

  • A person kneels over a reflective road sign during the sign-fabrication process.

    Every road sign serves one primary purpose: convey the most accurate information possible at the moment when each driver needs it in order to make a decision.

    Key to accomplishing this is delivering that message quickly, effectively and safely. While many factors can influence how this transpires, some are more critical to consider than others. We’ll address what “orientational uniformity” is and what role it plays.

    What is "orientational uniformity?"

    You may have heard the term “orientational uniformity” (or “rotational insensitivity”) to describe a characteristic of retroreflective sign sheeting.

    You might assume that, by using “orientationally-uniform sheeting,” the result guarantees a visually-uniform road sign—one that conveys all of its information consistently, regardless of the angle at which each element was installed on it. In theory, this might also provide more flexibility and material savings during fabrication, but the most important question remains whether or not the sign does its job well. 

The test: does orientation matter?

To test the assumption that “orientationally-uniform sheeting” yields visually uniform signs, we made two signs both according to each manufacturer’s recommendations.

On the first, we used 3M™ Diamond Grade™ DG3 4090 Sheeting (at the recommended orientations of only 0o or 90o). On the second, we used a competitor’s Type XI—a sheeting product advertised to be “rotationally insensitive” and provide “orientational uniformity” (which does not recommend any specific orientation).

  • A street sign reading “SMARTER?” is illuminated at night; all the letters are bright, and the sign is easy to read.
    3M™ DG³ 4090 Type XI Sheeting

    The letters (direct applied copy) in this sign were produced using 3M™ DG3 4090 Type XI sheeting using 3M’s recommended orientation (0o or 90o). The image was taken from the front seat of an SUV and was illuminated using headlights only.

  • A street sign reading “SMARTER?” is illuminated at night; only some letters are bright, and the sign is hard to read.
    Competitor's Type XI Sign Sheeting

    The letters (direct applied copy) in the above sign were produced using a competitor’s Type XI sheeting per their recommended orientation (any). The image was taken from the front seat of an SUV and was illuminated using headlights only.

The results: “rotationally-insensitive” sheeting does not necessarily ensure a visually-uniform sign

  • The signs in the photos above are manufactured with the same message. However, at a critical moment when the driver may need to make a decision, one delivers inconsistent brightness.  It would appear that using a “rotationally-insensitive” sheeting does not necessarily ensure a visually-uniform sign.

    For those concerned about finished sign uniformity, 3M recommends that all sheeting of the same color on the same (or adjacent) signs be installed in the same 0 or 90 orientation.

  • Get the Full Report

    Are you a traffic engineer looking for a better understanding of the effect of sheeting orientation on traffic sign performance?

    In the 3M Sheeting Orientation white paper you will find:

    • Sign manufacturing practices to optimize sign uniformity
    • The difference in retroreflective performance between 3M and a competitor
  • 3M Orientational Uniformity Competitive Video
    See for yourself.

What is Nesting?

  • Nesting refers to carefully planning designs in order to produce the required quantity of parts while minimizing the amount of wasted material.

    For signs, the technique is used to plan the production of sign components (letters, numbers, and other elements of a sign) before those components are cut from sign sheeting. The technique involves placing one sign component within another, closely positioning components, and rotating components. The cut components are then arranged and manually applied to the sign.

    In general, nesting improves material savings but makes for a more labor-intensive process—a decision that often makes economic sense, especially for large signs.

Our Recommendation

  • Our recommendation: all sheeting of the same color and on the same sign should be oriented in the same direction.

    At 3M, we recommend that all sheeting of the same color and on the same sign be oriented in the same direction, ideally in the 0 or 90-degree orientation. This helps ensure the best driver viewing experience and finished sign appearance.

    For the driving public, this means a quality sign with uniform legend that conveys the necessary message for years to come.

    For the sign fabricators, it means less risk of rework on signs that don’t meet the road owner’s standard for appearance.

Does it cost more to use only 0 and 90- degree orientations?

In short, not necessarily. To illustrate, let’s look at this example from a sheeting manufacturer’s brochure:

  • Figure 1: Letters and symbols are nested in order to be cut out efficiently; they face 0, 90, 180 and 270 degrees.
    Figure 1

    A nesting example from a competitor's brochure.

  • Figure 2: The letters and symbols are laid out without nesting to show what needs to be cut out
    Figure 2

    All the letters and shapes laid out so we can see what's here.

  • Figure 3: The letters and symbols are laid out in the same area as Example 1, but only at 0 and 180 degrees; all fit.
    Figure 3

    The letters and shapes nested together using only 0 and 90-degree orientations.

By constraining nesting to 0 and 90 degrees in this way, one might expect to consume and potentially waste more material. However, in the above example (Figure 3), we have reproduced all of the components at the same size and on relative sheeting dimensions, and everything fit. In the example shown here, the same amount of material was used in both nesting situations.  3M believes that signs that help to bring families home safely are more beneficial than saving a small amount on materials.