Section 2: Sign and Substrate Structure
Substrate
The sign substrate provides the rigid structural backing and shape for the sign. The substrate must be rigid enough to prevent the sign from flexing or waving in the wind or warping in the sun.
Common substrate materials are flat-sheet aluminum and extruded aluminum. Other substrate materials, such as plywood, roll-up and lightweight materials, may be used in work zones as per the
list.
Structural Support System
Some signs also require a structural support system. The
detail the types of materials,
thicknesses, support systems, and various other details.
contains specifications to be used in contracts.
Overhead Sign Walkways
Overhead sign walkways are designed so that maintenance personnel
can easily work on dynamic message signs. The walkways provide easy
access all along the bridge. Details regarding sign walkways are
provided in the
.
Overhead sign walkways are optional, since needs may vary
from location to location within the district. Factors to consider
are traffic conditions, anticipated maintenance, and maintenance
equipment available. Some dynamic message signs are manufactured
so maintenance personnel can walk inside the sign to perform basic
maintenance. A separate sign walkway is not needed on these types of
signs.
See Chapter 4 for information on overhead sign maintenance.