Nothing contained in this chapter shall be deemed to prohibit the operator of any truck traversing any of the hereinafter designated truck routes from leaving such routes for the purpose of loading or unloading said truck at a point off of said route; provided, that such deviation for the purpose of such loading or unloading shall be had over a route which keeps the distance traveled off of the truck route at a minimum. (Ord. 3727 § 2 (part); June 28, 1977.)