Letter Size

The Texas MUTCD provides guidance as to the letter height on guide signs. For freeway guide signs, the message dimensions and letter size must be determined first, and the outside dimensions second. Lettering size on freeway signs is dependent on the type of interchange or sign, and must be the same for both rural and urban conditions.
Letter and numeral sizes for freeway guide signs according to interchange classification and component of sign legend are given in the Texas MUTCD. The minimum and desirable sizes for sign elements on Advance Guide and Exit Direction signs are shown in the following table. The minimum sizes for sign elements on other types of freeway signs are provided in Chapter 3.
Minimum Letter and Number Sizes for Advance Guide and Exit Direction Signs
Type of Sign and Sign Elements
Minimum Height (inches)
Letter Style
Exit Panel
Word
10
CV 4W
Numeral and Letter
15
CV 4W
Interstate Route Sign
Numeral
1
18
D
Shield (1-2 Digit)
36 × 36
—
Shield (3 Digit)
45 × 36
—
U.S. or State Route Sign, Business, Loop, or Spur Interstate Route Sign
Numeral
1
18
D
Shield (1-2 Digit)
36 × 36
—
Shield (3 Digit)
45 × 36
—
Or Alternative (Ex: U.S. 56)
Initials
12
CV 5WR
Numerals
15
CV 5WR
Cardinal Direction
Word
2
12
CV 5WR
“BUSINESS”
Word
10
CV 5WR
Name of Place, Street, or Highway
Word
16
CV 5WR
Distance Message
Numeral
15
CV 5WR
Fraction
10
CV 5WR
Word
10
CV 5WR
NOTES:
1. In a few cases numerals cannot be accommodated within the space available. For these cases, the standard series D numeral may be reduced to C, or as a second choice to the next smaller height commonly available.
2. It is Texas practice that the entire cardinal direction word be the same letter size.
Examples of letter style and minimum letter and numeral sizes on an Advance Guide sign are shown in Figure 4‑10.
Letter style and minimum letter and numeralsizes on an Advance Guide sign. (click in image to see full-size image)
Figure 4-10. Letter style and minimum letter and numeral sizes on an Advance Guide sign.