Because curb space in an urban environment is a very limited resource and the city government determines how the competing interests are going to share it. One

Because curb space in an urban environment is a very limited resource and the city government determines how the competing interests are going to share it. One set of signs I pass rather often in Seattle looks (and probably is) complicated, but the reasoning behind it makes some sense. It is against a yellow-painted curb and says: - No parking 6a-9a / 3p-7p except Sat/Sun/Hol - 30-minute loading only 9a-3p / 7p-10p except Sat/Sun/Hol - 3-minute loading only 9a-11a Sun - <----- No parking Why? The adjoining property is a large church that sits on what is now a major arterial route near businesses. In order, the restrictions allow for commute hours traffic in that lane, reserve a zone for deliveries during the rest of the hours in a weekday, reserve a zone for parishioners to get out at the door of the church, and foreclose parking that is too close to the corner and a fire hydrant. Parking is, implicitly, allowed all day on Saturday when commute hours aren't in effect, some of the businesses are closed and the remainder are receiving fewer/no deliveries, and the church isn't in session.