The 911 renumbering in Alton was for the whole town. Many streets had no numbers and those that did were not standardized.
The standardized numbering used 50' increments on both streets and islands as well as standardized starting points.
http://www.nh.gov/safety/divisions/e...gstandards.pdf
While current laws require more than 50' frontage who knows about the future. One objective is to avoid future renumbering as housing becomes more dense.
Overall standardized numbering from town to town helps emergency responders locate the emergency. Also GPS coordinates were entered into the 911 data base for each unique address.