Notwithstanding the provisions of this chapter, overhead facilities may be installed and maintained for a period, not to exceed sixty (60) days, without authority of the director of public works in order to provide emergency service. The director of public works may grant special permission, on such terms as the director of public works may deem appropriate, in cases of unusual circumstances, without discrimination as to any person or utility, to erect, construct, install, maintain, use or operate poles, overhead wires and associated overhead structures. (Prior code § 7855)