the day, they are always used in conjunction with painted retro-reflective lines; they are never seen on their own. White markers — for lane markings. When used on dual carriageways, motorways or one-way roads, they may illuminate red on the reverse, to indicate drivers are traveling the wrong way. Yellow or amber markers — These are found next to the central reservation (US: median) on motorways and dual carriageways and, in the Republic of Ireland, are also used on hard shoulders. Red markers — These are found by the hard shoulder on motorways and at the edge of the running surface on other roads. They are also occasionally used to indicate a no-entry road and when travelling down the wrong way of the motorway/dual carriageway. Green markers — These are used where slip-roads (US: off-ramp) leave and join the main carriageway on dual carriageways. In some countries, they are also used across the entrances of minor roads or accesses onto major single carriageway roads or lay-bys. Blue markers — Are used to indicate the entrance to police reserved slip-roads (these do not lead anywhere, they are to allow police to park and monitor motorway traffic). The exception to the above rules are: Fluorescent yellow markers — These are used to indicate temporary lanes during roadworks on major roads and are glued to the road surface; they are never embedded in it. Any painted markings will be removed from the road surface if they contradict the markers. They are fluorescent yellow in color, so they stand out in the day, but reflect white light at night. Where used, they are much more numerous and dense than standards markers, as they are not used in conjunction with painted lines. They also appear yellow on the edges but reflect red on the left side or amber on the right Usage of color in North America White markers — for lane markings or to mark the right pavement edge. Yellow or orange markers — These separate traffic moving in opposite directions, or mark the left pavement edge on one-way roadways. Blue markers — Usually placed near the center of the roadway, offset to one side to mark the location of fire hydrants on the shoulder or at the curb. Green markers — Usually used to indicate that emergency vehicles can open gates to enter a gated community. Red markers — Usually indicate areas that