Sign Legibility Series...

Beginning with this issue of Signpower, the critical issue of Sign Legibility will be covered in a simplified "rule-of-thumb" format. As members are aware, The United States Sign Council and the United States Sign Council Foundation have spent well over a million dollars in research grants and staff and member in-kind contributions to make it possible for the industry to finally bring scientific credence to on-premise sign legibility and to the necessity for the presence of adequately sized signs in our high speed automobile dominated commercial environments.

The impact of this effort is enormous and has already had far-reaching effectiveness. It has given the USSC an unprecedented level of expertise in sign legibility and clearly has led other organizations to turn to USSC whenever the factors involved in how signs are perceived and understood in the landscape is an issue. In its signature sign code document, Street Graphics and The Law, published in late 2004, The American Planning Association uses the USSC Guideline Standards for on-premise sign legibility and sign size as the basis for the computation of freestanding sign size and heights. And, in a similar vein, the International Code Council, responsible for the development of virtually all building codes in the United States, has adopted the USSC Guideline Sign Code as the basis for its zoning regulation of on-premise signs. None of this, of course could have taken place without the foresight of USSC in funding the research and in developing the standards for on-premise sign legibility.

Now that the critical research work is done, it is important, we think, that as many sign people as possible be able to use it to their advantage, and to the advantage of the industry. The signs we make, after all, are a visual medium displayed throughout the commercial landscape. They depend on superior visibility and clear legibility for their effectiveness, and it is up to us who design and make them to have at least a working understanding of how those two critical factors can make all the difference in creating signs that can communicate messages efficiently and rapidly.

We need to be able to make this knowledge available to our customers, who certainly deserve the best professional counsel we can provide. And, as well, we need to make this knowledge available to those who regulate the industry so that they can come to understand that the sign codes they enact must always take into account the need for adequate size and height requirements necessary to ensure motorist legibility and safety.

This series on Sign Legibility is intended to help you fill those needs, and to gain an understanding of how a knowledge of this critical central aspect of sign design can make your work accepted on a much higher professional scale by both your customers and your local legislators. We suggest that you save the Signpower issues and refer to the series as often as necessary to gain the knowledge it can provide. The first article in this issue will cover visibility and height parameters for perpendicular signs, how to compute viewer reaction time and distance, how to use the USSC Legibility Index for letter heights, and how to compute negative space. In future issues we will address how to compute the size of signs for various speed of traffic scenarios using viewer reaction time and the Legibility Index as well as the formulas developed to simplify the process, and the final installment will cover how to compute adequate sizes for parallel signs with simplified formulas and tables.

For USSC members, the full text of all three installments is also available as Sign Legibility Rules-Of-Thumb on our website, www.ussc.org on the member services page. You will need to use your member identification and member password to access it in PDF format, which you can then download.

Back