ClearviewHwy

	Letterform Design

	Letterspace

	Development Criteria

	Comparisons


The ClearviewHwy spacing was developed based on controlled review of full size samples viewed at threshold to determine spacing for optimal readability for each specific typeface. Based on these designs, reduction of letterspacing to accommodate a specific size sign panel is discouraged because the visual attributes of the typeface in combination with letterspace will be compromised. Downloadable letterspacing charts are available within this website for each version of ClearviewHwy These dimensions are available for either metric or English dimensions and are identical to the Clearview charts included in the FHWA Standard Highway Sign book. The principles of calculating letterspaces for ClearviewHwy are identical to those specified for FHWA Standard Alphabets for Traffic Control Devices as show on pages 9-1 to 9-5 of the 2000 Standard Highway Signs book, but the individual dimensions for each letter are different for ClearviewHwy because they are based on the shape of each individual letter and its relationship to the adjacent letters. Based on a 100 millimeter (metric), or 4 inch (English) capital letter height, each letter has a value for letter width, and a value for the side bearings on the leading edge and the trailing edge of each letterform (Figure 1).

Figure 1.

The right side bearing is an average volume of space that when abutted to the left side bearing of the next letter will create even letterspace for that word. With 100 millimeter capital letter height as a basis for metric or the 4 inch for English, words can be proportionally spaced to any size. While this approach to letterspacing legends will simplify the layout process, it continues to have drawbacks because these side bearing dimensions are based on a average space and have been rounded to the nearest millimeter or fraction of an inch depending on the chart used, and the 676 pairs of standard letterspacing for each typeface. Since millimeters or inch fractions are a very coarse measurement relative to digital font production, manual spacing tables will not apportion letterspace in as refined a manner as can be done electronically using the ClearviewHwy font software (Figure 2).


Figure 2. Letters spaced with manual chart (middle) vs. letters spaced with software using auto kerning (bottom)

This program contains the correct letterspacing, and can be scaled proportionally in any standard unit of measure including inches, millimeters or points. In addition to the letterspacing being built into the software for each typeface in of the ClearviewHwy Type System. The program contains subtle kerning adjustments that enhance and improve letter fit based on thousands of letter combinations. Kerning is most noticeable with letter combinations in which the leading or trailing edge of one or both letters creates an unusual space such as “Te, ra, or Yo” that can not be averaged in all letter combinations. Not all applications support kerning data. Check with your applications manufacturer to learn if kerning is supported in the application. Lack of kerning does not detract from readability, but it does enhance the uniformity of the overall word as placed on the sign. Using the software, the word length will vary slightly (+/-) as calculated from the published spacing tables, but the letters will appear more precisely spaced than manually calculated letter combinations. Use of the ClearviewHwy font software allows design engineers and fabricators to know the length of a legend when creating a layout and allows legends to be pre-spaced when cut on a computer plotter. If letters are manually placed on signs, the most accurate and efficient method is to plot a full size paper outline print of the legend using the default letterspacing kerning the software. This plotted sheet, with baseline drawn, can then be used as a precise word layout template. Note that for letters applied by hand, the baseline is critical because it will show precisely how much the round letters descend from the baseline. Using a full size, or scaled plot the precise distance from trailing edge to leading edge can be measured and applied to the manual application of individual letters to the sign face. Software industry specifications for TrueType and PostScript2 are the standard for most layout and production programs. These font formats are the same as used for other computer-based programs such as word processing. The latest versions of these specifications use a standard called OpenType which is cross platform compatible. 1 TrueType refers to Microsoft Corporation standard font format description and specification. 2 PostScript refers to Adobe Systems Incorporated standard font format description and specification.