99- 420 C.M.R. ch. 3, § 3
The MUTCD states that "sign installations are an integral part of the facility, and as such are best planned concurrently with the development of the highway locations and geometric design. Interstate signing is to be considered and developed as a planned system of installations. An engineering study is sometimes necessary for proper solution of the problems in many individual locations but in additional consideration of an entire route is necessary."
Modification or installation of supplemental guide signs requires review of the surrounding area. Moving or eliminating other signs may be required to achieve a proper overall signing design in accordance with national standards. Signage is typically adjusted every 15-20 years as the life of most of the signs is reached and replacements are planned. In addition, as new facilities are built or new interchanges are built or under major rehabilitation considerations for adjustments in signs will be made. Therefore, requests for changes to signage under this chapter which are granted may not be actually put into effect by the Authority until a later date consistent with the Authority's long term planning and operations.
99- 420 C.M.R. ch. 3, § 3