As a former transportation planner, I can tell you that speed limit signs are fairly arbitrary and capricious, and yet they have a certain relationship or that we, as drivers still need to be cautious of actual driving conditions, and so it’s interesting to me to draw analogy between how Speed limit signs are a necessary but not sufficient condition. Safe driving and the actual, what’s called design speed of the road is what gets a lot of thought in planning, not speed limit signs. Likewise, we think of time. As this fixed interval of me numb numeric measure when we should be thinking about it in terms of sequence, but The concept of numeric times still has meaning and relatives. It is also necessary, but not ssufficient his sufficient hisufficienthis