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There are three basic types of hinge designs. One type, illustrated in Fig. 7.30a, develops a hinge by cutting through all but the back flange. The front flange is connected with a slotted plate known as a friction plate. When the post is struck, the friction plate sepa­rates from the slotted bolt holes as the […]

Inclined slip base designs, commonly used for single sign supports, cause the sign to rise up upon impact and allow the vehicle to pass beneath the sign. In a multiple-sign- support system, each support is fastened to the other supports by the sign panel and any existing sign panel bracing. When an inclined slip base […]

There are few single-support systems that can be buried directly and provide accept­able multiple-support performance upon impact. Two such systems are dual 3-lb/ft (4.5-kg/m) U-channel and dual 4-in X 4-in (90-mm X 90-mm) shaped wooden posts. The majority of single-support adaptations to multiple-support assemblies require the use of anchor pieces and breakaway designs. Triple supports […]

Multiple-mount sign-support assemblies (Fig. 7.22) are required whenever the surface area or width of the sign is too large to withstand the wind and ice loads. Each state has guidelines, in the form of tables and graphs, that are used to select the size and numbers of supports required to withstand the prevalent environmental loads […]

Acceptable single-sign-support performance can be achieved with the use of frangible couplings and load concentration couplers (Fig. 7.21). These couplings are either fabricated from die cast aluminum or extruded from an alloy. The couplers are used as inserts that bolt the support post plate to the anchor piece plate. They present a weak point on […]

The multidirectional slip base design operates on the same principle as the inclined slip base design. The multidirectional design consists of a triangular slip base employing FIGURE 7.19 Typical inclined, unidirectional slip base. Dimensions shown as mm: 100 mm = 4 in. only three slotted bolt holes, as presented in Fig. 7.20. The bolts are […]

Unidirectional slip bases for small sign supports consist of inclined slip bases, as shown in Fig. 7.18. The upper support piece is made from rolled-steel shapes, standard pipe, or structural tube. The base of the support assembly is inserted into a concrete footing to prevent movement of the anchor assembly. The upward thrust obtained from […]

Slip base designs for small sign supports consist of two components: (1) the anchor assembly up to the bottom of the slip base, and (2) the sign support, containing the top of the slip base on the lower end and the sign panel on the upper end. Small sign slip bases are categorized as unidirectional […]

Steel-pipe posts are frequently used in urban areas and have the advantage of being readily available. They require special fastening hardware, and an earth plate when directly embedded, to prevent the post from rotating from its intended position. Standard steel pipe, schedule 40, galvanized, is readily available from plumbing supply wholesalers. The maximum sign panel […]

Square steel-tube sign supports are used in many localities. They provide four flat sur­faces for mounting sign panels, facing different directions, without special hardware as required by some support types. Square-tube supports can be purchased from a number of manufacturers and are available with %s-in (11-mm) holes or knockouts at 4-in (25-mm) centers on all […]