North West Motorway Police on X: "Marker posts are blue & white metal shields on motorway side. Eg Marker post 280.4A is 280.4km north of start of M6.. http://t.co/bJJes1UaAi" / X
Driver Location Signs | Roads.org.uk
CMPG on X: "Do you know what motorway marker posts mean? You do now! http://t.co/Zxd90KYA4q" / X