The Texas MUTCD classification scheme (described in the preceding subheading) is somewhat difficult to apply to many interchanges, and the differences are not typically significant. For the purposes of this handbook, the interchange descriptions have been simplified to address the following design considerations:

Guide Sign Letter Height.

The letter height guidelines provided in Table 2E-2 of the Texas MUTCD have been simplified so there is only one minimum letter height option. As a result, it is not necessary to distinguish between interchange types to determine the appropriate letter height. Larger letter heights may be appropriate in some situations.

Number of Advance Guide Signs.

The Texas MUTCD requires one Advance Guide sign for minor interchanges. Two, and preferably three, Advance Guide signs are used for other interchanges. The following definition of a minor interchange (requiring only one Advance Guide sign) is based on the Texas MUTCD definition of a minor interchange.

Minor Interchange

— An interchange where all traffic exiting the freeway at the interchange (for all exits at the interchange from both directions) is estimated to be 100 vehicles per day or less in the design year (typically 20 years into the future).