"First, thanks for this service, it is nice to be able to ask questions anonymously………. Regarding a construction zone, if the construction is on the south side of a four lane highway, not divided, are you still required to follow the construction zone speed if you are traveling north where there is no construction? What if it is late at night with no work being done? Also, what does the sign refer to as you come on to the entrance ramp to, say I88, and it reads No motor driven vehicles allowed?"
Unless the zone is marked in the direction you are travelling, you would not be subject to any special speed zone. Zones sometimes only involve one direction of travel on a highway. If the Zone encompasses both directions, it should be clearly marked in both directions of travel.
If a work zone is marked as such, with a reduced speed zone, this applies 24 hours a day, regardless of whether or not work is ongoing. This is because special hazards may exist in the work zone that warrant the lowering of the speed limit.
The sign you are referring to most likely states that no "motor driven cycles" are allowed. A motor driven cycle is a motorcycle or motor scooter with less than 150 cc's. These are very small motorcycles, scooters, or Mopeds that may not have enough power to allow them to operate continuously at Interstate Highway speeds. Interstates are limited access highways, for example bicycles and pedestrians are not allowed, whereas these slower moving things can use other roadways and streets. Hope that information is helpful.