Wind Loading Considerations - ABB MicrOS 410 Installation Manual

5

Wind Loading Considerations

The American Association of State Highway and Transportation Officials (AASHTO) standards
manual, "Standard Specifications for Structural Supports for Signs, Luminaires and Traffic
Signals," governs most structural support issues related to traffic lighting and controls. Many
state and city public works departments site the AASHTO standard as the guide for their
requirements. Local municipalities in coastal states, which experience frequent hurricanes, etc.,
may have exceptions to the AASHTO standard that require higher design limits for wind
velocity or dead load.
Numerous pole and mast arm assemblies are used for traffic controls and traffic lighting. Each
assembly and installation is unique and worthy of an evaluation of the static and dynamic load
bearing capabilities; however, in most cases, the assembly will include a pole with a single 6', 9'
or 12' mast arm holding a single luminaire. Many of these mast arms are typically designed to
hold hundreds of pounds of static load and to carry several square meters of sail area in 80mph
winds. The typical mast arm is capable of supporting a single traffic control (typically weighing
around 160 lbs) and a single traffic sign (typically presenting a few square meters of sail area). A
single luminaire typically weighs about 60 lbs and presents about 3 square feet of sail area.
Note
Each assembly and installation is unique and worthy of an evaluation of the static and dynamic
load bearing capabilities. It is your responsibility to evaluate the load bearing capabilities of the
structure.
The router weighs approximately 4 lbs, including all mounting hardware. The router can be
mounted to the pole portion of the streetlight or to the mast arm portion.
When the router is mounted to the pole or mast arm, most of the unit is hidden by the pole or
mast arm and therefore presents minimal additional sail area to the structure. When the router is
mounted to the pole portion of the structure, the sail area of the router is approximately 1 square
foot. Pole manufacturers have advised ABB that small communications devices do not present
any significant static or dynamic load to these structures.
MicrOS 410 Installation Guide 34