Before revision: The tar was modified by adding small amounts of Portland cement, resin, and pitch.Hooley, E. Purnell, , "Apparatus for the preparation of tar macadam", July 26, 1904 Historical map of the Autostrada dei Laghi ("Lakes Motorway"; now parts of the A8 and A9 motorway ) opened on 21 September 1924, Italy, the first controlled-access highway ever built in the world.
After revision: The tar was modified by adding small amounts of Portland cement, resin, and pitch.Hooley, E. Purnell, , "Apparatus for the preparation of tar macadam", July 26, 1904 Historical map of the Autostrada dei Laghi ("Lakes Motorway"; now parts of the A8 and A9 motorways ) opened on 21 September 1924, Italy, the first controlled-access highway ever built in the world.