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Multiple sign supports are designed to operate correctly when either one or all of the sup­ports within a 7-ft (2100-mm) radius are impacted. When only one support is impacted, the remaining signpost should support the sign and prevent it from penetrating the wind­shield. The desired impact performance of slip base and frangible coupler designs for […]

Slip base designs for multiple sign supports are usually of horizontal design as shown in Figs. 7.23 and 7.26. Horizontal slip bases, when used in multiple-sign-support systems, operate satisfactorily when impacted from only one direction. Horizontal slip bases should not, therefore, be used for multiple sign supports where there is a high probability of impacts […]

Transpo Industries manufactures a series of breakaway systems for ground-mounted sign supports, marketed under the trade name Break-Safe. The Break-Safe system uses frangible couplers and is available for U-channel, both concrete footing and direct burial; 3-in to 4.5-in (75-mm to 115-mm) round pipe; 3-in to 5-in (75-mm to 127-mm) square FIGURE 7.46 Weakened wooden post […]

Multimount sign supports have two or more support posts of breakaway design. The breakaway mechanism is either a fracture or a slip base type. Fracture mechanisms consist of frangible couplers or frangible one-piece posts. 7.8.1 One-Piece Multiple-Mount Sign Supports Direct burial assemblies that are approved for use include dual 3-lb/ft (4.5-kg/m) U-channel and dual 4-in […]

The following guidelines should be followed for fastening sign panels to supports: • Bolts smaller than %s in (8 mm) should not be used to fasten sign panels to the support. The bolts must be long enough to provide for bolt extension beyond the fastening nut. • Carriage bolts, or hex bolts with washers between […]

Regardless of the type of support that is being used, there are three general rules that must be followed: (1) the top of the sign should be 9 ft (2750 mm) above ground level to reduce the possibility of intrusion into the passenger compartment upon impact, (2) the retaining bolts must be snug but not […]

Slip base designs for single sign supports provide the opportunity to use stronger sign supports than would be possible without the slip base design. The purpose of the slip base is to provide a separation plane between the sign support and the anchor system. The two pieces are fastened together with bolts that must be […]

The correct installation of sign-support assemblies is dependent upon the type of sup­port post, the type of soil present, and the impact performance design of the sign assembly. Installation instructions are contained in standard state drawings and, for proprietary devices, from signpost manufacturers. Proper installation practices for the most common types of single support assemblies […]

An important element of a safe highway environment is the proper construction and maintenance of traffic signs. Good designs and the best of materials will not be effective in reducing accident potential or severity if the traffic signs are improperly placed or installed. This requires that field crews be knowledgeable of proper installation tech­niques and […]

A number of manufacturers have developed products so that the anchor piece can be placed almost flush with the ground. These products can be used either to retrofit FIGURE 7.31 Commercially available hinge plates by Transpo Industries. existing slip base designs or for new installations. One such manufacturer is Transpo, which markets the Breaksafe breakaway […]