Overly enforcing; posted limits difficult to maintain. After the lights where you enter onto Route 3N from Exit 17 on Route 93 the limit of 35 is not posted for several hundred feet. Before then the limit varies from 45 mph to 50 mph to 35 mph over about a 3/4-mile distance, which is maddenikng. But you are going 50 mph for a good stretch but then suddenly you have to slow from 50 to 35 very quickly, while going downhill, in anticipation of the lights. If you go through the lights the limit is not posted for a few hundred feet and you are likely going 45 mph. Suddenly the limit is 35 mph and you get caught.