Poles are available in a number of materials. The advantages and disadvantages of each follow.
Steel. Steel poles are available in galvanized, painted, powder-coated, and weathering types, plus a combination of powder coating over galvanizing. Galvanized is the most popular of the steel types because of the comparatively low cost and extended life. Painted poles are used primarily when a color is desired, but they require continual maintenance. The powder coating over galvanizing serves the same purpose and requires little maintenance. Weathering steel poles offer enhanced aesthetics but provisions must be made for the rusty runoff.
Aluminum. Aluminum poles are popular because of their resistance to corrosion and the resultant low maintenance cost. They have an added advantage of being lighter in weight than most other types. Aluminum poles operate well as breakaway designs when impacted at the design height. Since they are less rigid than steel posts, however, aluminum poles can result in an increased probability of improper breakaway operation when impacted higher than the design height. Aluminum poles are also considerably more expensive than most other types.
Stainless Steel. Stainless steel poles are corrosion-resistant and relatively lightweight. Their high rigidity results in dependable breakaway operation upon impact. They are, however, considerably more expensive than the other pole types.
Fiberglass. Fiberglass-reinforced plastic (FRP) poles are approved for breakaway use both in the anchor base and in the direct burial series. Shaft lengths are currently limited to 47 ft (14.3 m), which means 39 ft (12 m) height for the direct burial series and the full 47 ft (14.3 m) height for the anchor base series. Advantages of FRP poles include no rust, no corrosion, no rot, lightweight, no additional breakaway device required, no maintenance, no electrical shock, and, for the direct burial series, no need for concrete foundation. FRP poles come in many decorative styles and several standard colors.
Wood. Wood is perhaps the least expensive of pole types, particularly in areas where trees are plentiful. They can be treated to resist deterioration from the environment and damage due to insects. The use of existing utility poles for luminaire placement has the advantage of reducing the number of poles on the roadside. The huge mass of wood poles, however, makes it difficult to design them as breakaway, and thus, wooden poles should not be installed on high-speed facilities.
Concrete. Concrete poles are popular in regions where cement and concrete aggregates are plentiful. One advantage to concrete poles is that they can be economical. Concrete poles cannot, however, be designed effectively to safely break away upon impact. They are extremely heavy even when made by prestressing concrete. Impacts with concrete poles result in extensive damage to vehicles and severe injury to occupants. Prestressed concrete poles, therefore, should not be used within the traversable area, unless shielded, on facilities with design speeds over 30 mi/h (50 km/h). Concrete posts can be a functional and economical type of support on local urban streets if proper consideration is given to placement.
