(2)The width of such projected streets, inclusive of footpath, shall not be less than ten metres :Provided that -(a)the Board of Councilors may, for special reasons, reduce the requirement of width of any projected street; so, however, that the width of any such projected street shall not be less than six metres; and(b)the Board of Councilors may relax the requirement of width to any extent in case the projected street is, in effect, in widening of an existing street.