Section 1225-A. Driving on sidewalks

No person shall drive a motor vehicle
  on or across a sidewalk, except that  a  vehicle  may  be  driven  at  a
  reasonable  speed, but not more than five miles per hour, on or across a
  sidewalk in such manner as not to interfere with the safety and  passage
  of  pedestrians  thereon,  who  shall  have the right of way, when it is
  reasonable and necessary:
    (a) to gain access to a  public  highway,  private  way  or  lands  or
  buildings adjacent to such highway or way;
    (b)  in  the  conduct of work upon a highway, or upon a private way or
  lands or buildings adjacent to such highway or way, or
    (c) to plow snow or perform any other public  service,  for  hire,  or
  otherwise,   which  could  not  otherwise  be  reasonably  and  properly
  performed.