There's another course I measured, the Westport Summer Series 10 miler CT00028DR where runners are not only allowed to run on the sidewalk that cuts a corner, but are instructed to do so (it avoids a bad traffic intersection and the water station is set up on the grass between the sidewalk and road). Since it is the "official" course that is how I measured that one.
Scott, in both cases it's pretty obvious where runners should hop on the sidewalk to cut the course.