a. No person shall drive upon, across or within any sidewalk area except at a permanent or temporary driveway.
b. The provisions of this ordinance shall not apply to three-wheel electric delivery vehicles of the United States Post Office being operated in a residential area for the delivery or pickup of mail. Said vehicle shall not be operated upon any sidewalk at a speed in excess of eight miles per hour.
c. The provisions of this ordinance permitting the United States Post Office to utilize City sidewalks for the delivery of mail through the use of electrically powered carts shall not be operative until such time as it has filed an indemnity agreement with the City of Phoenix whereby it assumes all liability for injury and damages occasioned by its use of the sidewalks as referred to above. (Code 1962, § 37-26.02; Ord. No. G-1324, § 1)