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''This article uses the word pavement in its US English sense: i.e. the surface of a vehicular road'' Pavement marker is an American English term for any kind of device that is used on Pavement to convey information. Paint, plastic and epoxy are also used to mark pavements and are covered in the Road Marking article. Countries and areas categorize pavement markings in different ways. In the U.S. , the type, placement, and graphic standards of Traffic Signs and pavement markings are legally regulated — the Federal Highway Administration 's '' Manual On Uniform Traffic Control Devices '' is the standard, although each State produces their own manual based upon the Federal manual. TYPES OF MARKERS Pavement markers are either Mechanical , or temporary. They can be used to delineate traffic lanes, instruct motorists and pedestrians or serve as noise generators when run across a road, or attempt to wake a sleeping driver when installed in the shoulders of a road. MECHANICAL MARKERS Mechanical devices can be either raised or recessed into the pavement and either Reflective or non-reflective. While generally permanent, they may also be moveable. Bot dots (low rounded white dots), sometimes called Botts' dots after the California engineer who came up with the idea, is one type of a mechanical non-reflective raised marker. Generally they are used to mark the edges of traffic lanes, frequently in conjunction with raised reflective markers. Bot dots are also used across a travel lane to draw the drivers attention to the road. They are frequently used in this way before Toll Booth s to get the drivers attention so they slow down or when a significant drop in speed has happened like going into a School Zone . They are normally only used in warm climates since Snow Plows usually remove them along with the snow. Similar to Bot dots, "rumble strips" are comonly used for the same purpose. A rumble strip is a simple trough (typically 1 cm deep and 10 cm wide) that is ground out of the asphalt or concrete in a perpendicular line across a roadway or shoulder. Usually closely grouped together, 5 or 10 of these troughs create a loud vibration when driven over that will alert a driver to various upcoming hazards. This type of rumble strip could be used to warn a driver of an approacing stop sign in a rural area. Another form of the rumble strip is continuously placed on the shoulder of a highway to wake drivers that may fall asleep while driving. Crossing the rumble strips placed on the shoulder of the road can wake the weary driver before they drive into the ditch. Reflective Markers , known as Cat's Eye in some countries, are used as travel lane dividers. By being reflective, they are more visible at night and in inclement weather. White and Yellow indicate their usual message while Red is used to indicate that you are traveling the wrong direction in a lane. These markers can also be used for other purposes such as marking the locations of Fire Hydrant s (blue) or at gates to gated communities to indicate that emergency service vehicles have a code or device that allows them to open the gate. In some countries like the United Kingdom , raised markers are also used to mark crosswalks to assist the blind in crossing streets. In colder climates, reflective markers can be installed below ground using an elongated narrow triangle, cut into the pavement that allows the device to be installed below the road surface. Newer technology now allows these to be placed above ground with snowploughable rails that attempt to protect the reflective components from the snowplough blade. TEMPORARY MARKERS Pylons are sometimes used to separate HOV lanes from regular traffic lanes. They are also used in areas where lanes are used at different times for travel in both directions. These pylons have shafts that drop into holes in the pavement. A good example of this type of use is the Golden Gate Bridge in San Francisco . |
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