It shall be unlawful to conduct or engage in outside construction activities regulated by this title between the hours of nine p.m. and seven a.m. in any area of the city located in a residential zone or directly abutting a residential zone; provided, however, that this section shall not prohibit the emergency repair of utilities or streets or the construction of utilities or streets where operations are necessary during such hours in order to promote the safety of the traveling public. (Ord. 837 §1, 1988).