The Bradfield Highway carries six lanes of traffic across the eight lane Sydney Harbour Bridge. The other two traffic lanes on the Sydney Harbour Bridge are used for the Cahill Expressway, which run only southbound on the bridge. During peak periods three out of the six lanes are reversed, giving a 2 × 4, 3 × 3 or 5 × 1 flow. The default is 4 × 2. (Four north, two south) The direction of the lanes is indicated by electronic signage above each lane. The lanes are numbered one to six from west to east. Lane six was also reversed prior to 1990 during the evening rush hour, giving a 6 × 0 flow, but this no longer occurs because of changes made to the Warringah Freeway to accommodate the Sydney Harbour Tunnel.