Section 281. Municipal improvements in streets

No public municipal street
  utility or improvement shall be constructed by the town in any street or
  highway within  that  part  of  the  town  outside  the  limits  of  any
  incorporated  city  or  village  until  it has become a public street or
  highway and is duly placed  on  the  official  map  or  plan,  provided,
  however,  that subject to the discretion of the town board, a subsurface
  utility or improvement operated for revenue by the town or by a  special
  district  may be constructed by the town in a private street, provided a
  public easement satisfactory to the town  board  is  obtained  for  such
  utility or improvement.