Supports for traffic signals are not usually of the breakaway type, because of the potential consequences of the loss of the signal at an intersection. Supports in the clear
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zone should be shielded. Call boxes can often be located behind existing barriers, but a breakaway support is an option. The call box should be securely attached to its support to prevent windshield penetration if dislodged. At highway-railroad crossings, highway and railroad officials should cooperate in deciding on the types of warning devices needed, such as crossbucks, flashing lights, or gates. If the support for the device is located in the clear zone, consider shielding it with a crash cushion. There is seldom room for a longitudinal barrier. Fire hydrants have not been tested to current criteria, but at least one breakaway design is available that includes immediate water shutoff after impact. Mailbox supports should be embedded no more than 24 in (600 mm) in the ground and not set in concrete, the mailboxes should be attached to the supports so that they will not separate after impact, and multiple mailboxes should be spaced apart by a distance of three-fourths of their height.
