15. The centre line of the carriageway shall be marked on the crossing between the stop lines mentioned in paragraph 12 and for a distance of 12 metres on each side of the railway measured along the centre of the carriageway from stop lines with a reflectorised double continuous line road marking of the size and type shown in diagram 1013.1A in the Regulations. The centre line shall be continued for a distance of 24 metres on each side of the railways measured along the centre of the carriageway from the ends of the double continuous line with a reflectorised continuous line and a broken line on its right hand side of the size and type shown in diagram 1013.1D in the Regulations.