Page:UK Traffic Signs Manual - Chapter 7 -The Design of Traffic Signs 2013.pdf/104



Existing signs sometimes need to be altered to take account of the opening to traffic of a new road, or other changes to the highway network such as reclassification. These alterations can take the form of new or deleted destinations, changes to route numbers etc. To save the cost of providing a completely new replacement sign, it is often possible to modify an existing sign by the application of cover plates. In no circumstances may smaller X—heights or sub-standard spacings be used to accommodate alterations.

Care should be taken to ensure that the sign face materials used to manufacture a cover plate match as far as is possible the materials used for the manufacture of the original sign. Problems that are likely to occur are mis-matched colours and mis-matched retroreflective properties. It is not uncommon to recognise a plated sign at night by a highly reflective "panel" on what is otherwise a relatively dark sign. Such methods of sign modification should be avoided, as they give unwarranted emphasis to a particular section of the sign. Where the intention is to remove the plates at a future date, they should be affixed to the sign in a manner that does not cause damage to the original sign face (other than the drilling of holes).

Where future changes are anticipated, it may be possible to design a sign with these changes in mind. However, the initial design of the sign should follow the design rules detailed in this chapter.

Where a sign is altered by the application of plates, and the sign had not previously been designed to take account of the specific changes, care must be taken to ensure that the modified sign still accords with the design rules, particularly with respect to block spacing. On map type signs it is important that the minimum space for unrelated blocks is maintained. Where a place name is removed from a list of destinations, a single line cover plate should not be used if this produces an artificial gap in the list. In this case a complete cover plate containing 103