Many residents have asked why the contractor is excavating so deep. The road is not being lowered as much as it may appear right now. There are areas where the road IS being lowered 6 to 12 inches from where it was. In those areas, the cut seems even deeper. The reasoning behind such a deep cut is something called an "under cut." Some soil is considered unsuitable or unstable; this is usually black dirt. When the subgrade (what's below the road and stone) is considered unsuitable or unstable, we under cut it. In this case, one foot below subgrade. That under cut is then filled with 3" stone to create a stronger subgrade. If the road does not need an under cut, then it just gets filled with smaller sized stone.
Either way, the top of curb (where your grass meets the curb) to the bottom of the smaller sized stone that goes everywhere (under cut or not) measures 20". When we add one foot of under cut, we're talking 36" (three feet!). And that is why it seems so deep.