They were allocated as follows:  In 1993, Sydney's Metroad system was introduced, with its prominent, blue-on-white hexagonal shields. There were initially six metroads: Metroad 1 replaced National Route 1 within the metropolitan area, Metroad 2 replaced parts of State Routes 28 and 30 (and was subsequently absorbed by the M2 Hills Motorway), Metroad 3 replaced State Route 33 (once Ring Road 3), Metroad 4 replaced the F4 Freeway and the metropolitan part of National Route 32, Metroad 5 replaced part of the metropolitan part of National Highway 31 and Metroad 7 replaced State Route 77. Later, Metroad 6 replaced State Route 45, Metroad 9 replaced the metropolitan part of State Route 69 and Metroad 10 replaced State Route 14 south of Mona Vale. There was never a Metroad 8. In 2013, the state replaced its entire system of State Routes, National Routes, National Highways and Metroads with an alphanumeric route numbering system. All numbered routes are allocated a letter (M, A or B) in addition to its number, with 'M' routes denoting motorways, 'A' routes denoting routes of national significance, and 'B' routes denoting routes of state significance. Instead of shields, the route numbers are displayed as yellow text on green rectangular background outlined in white. The changeover to alphanumeric routes was announced from March 2013 and signs were updated throughout 2013, either by removing old "shield" coverplates installed on newer signs, or installing new alphanumeric coverplates on old shielded signs. In 2020, the styling of the markers was modified to remove the white border, aligning with all other states except the ACT.