Sentence Correction

Despite what was hoped, the introduction of a 65 mile per hour speed limit is reducing neither congestion on rural highways, or it is not contrbuting to save gas for trucking companies and less pollution from the decreased amount of time trucks spend on the road.

Correct ans
not reducing congestion on rural highways, nor is it contributing to lower gas costs for truck companies or less pollution.

Question

Correct to use Not in place of neither. I did not choose this correct answer as I thought that neither nor always go togehter.

OR is it just neither always needs nor but nor can also be used with not.

Thanks
Khurram