If a majority of the qualified voters voting at such election shall have voted for such additional tax, it shall be the duty of the county commission to make the levy for such district, which levy shall not exceed the amount named in the order calling such election. Such levy shall be in addition to other taxes which the county commission is authorized to levy as provided by law. The tax so authorized by such district shall be collected in the same manner and at the same time as state and county taxes are collected and placed to the credit of the road district authorizing such special levy.