Road surface marking is any kind of device or material that is used on a road surface in order to convey official information.

Road surface markings are used on paved roadways to provide guidance and information to drivers and pedestrians. Uniformity of the markings is an important factor in minimizing confusion and uncertainty about their meaning, and efforts exist to standardise such markings across borders. However, countries and areas categorize and specifiy road surface markings in different ways.

Road surface markings are either mechanical, non-mechanical, or temporary. They can be used to delineate traffic lanes, inform 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.

There is continuous effort to improve the road marking system, and technological breakthroughs include adding reflectivity, increasing longevity and lowering installation costs.

History

In the United States, two states claim to be the first to have developed center lines. According to the state of Michigan, painted white center lines were developed by Edward N. Hines, the chairman of the Wayne County, Michigan, Board of Roads. They were first used on roads in Michigan around 1911. According to the state of California, Dr. June McCarroll was the first to develop center lines, in 1917. In 2002, a portion of Interstate 10 was designated and signed as "The Doctor June McCarroll Memorial Freeway" in her honor.

White center lines were used in the United States until the 1971 edition of the Manual on Uniform Traffic Control Devices, which mandated yellow as the standard color of center lines nationwide (after several decades of debate on the issue).. Yellow was adopted because it was already the standard color of warning signs, and because it was easy to teach drivers to associate yellow lines with dividing opposing traffic and white lines with dividing traffic in the same direction. In turn, this greatly reduced head-on collisions and improved road traffic safety. The major downside to the MUTCD white-yellow system is that yellow has slightly less contrast than white, especially at night, so for maximum contrast, bright yellow (and highly toxic) lead chromate was used to paint yellow lines through the end of the 20th century. As a result, U.S. transportation workers must take special precautions when disturbing or removing yellow lane markings.

In England, the idea of painting a centre white line was first experimented with in 1921 in Sutton Coldfield, Birmingham. Following complaints by residents over reckless driving and several collisions, the Sutton Coldfield Corporation decided to paint the line on Maney Corner in the area of Maney.

In 1971, a correspondent for the Sutton Coldfield News wrote an article in the newspaper recalling the event.

Mechanical markers

Mechanical devices may be raised or recessed into the road surface, and either reflective or non-reflective. Most are permanent; some are movable.

• Cat's eye , invented by Percy Shaw in the 1930s, Cat's eyes equip most major routes in the British Isles. They consist of four reflect lenses mounted in a durable white rubber housing, two facing fore and two facing aft. The housing is mounting within a cast iron shoe, which the rubber housing sinks in to when driven over. This provides protection from snow ploughing and allows the lenses to be self-cleaning - they pass a rubber blade when depressed. The lenses are available in a variety of different colours, mainly white, yellow/orange, green, red and blue.

• Botts' dots (low rounded white dots), named for the California Caltrans engineer, Elbert Botts who invented the epoxy that keeps them glued down, are 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. Botts' dots are also used across a travel lane to draw the drivers attention to the road. They are frequently used in this way to alert drivers to toll booths, school zones or other significant reduction of speed limit. They are normally only used in warm climates since snow plows usually remove them along with the snow.

• Rumble strips are commonly used for the same purpose. A rumble strip can be a series of simple troughs (typically 1 cm deep and 10 cm wide) that is ground out of the asphalt. Other alternatives, similar to the Botts' dots, use raised strips, painted or glued to the surface. Uses can be across the travel direction (to warn of hazards ahead) or along the travel direction (to warn of hazards of not staying within a specific lane). Their main way of function is creating a strong vibration when driven over that will alert a driver to various upcoming hazards both by sound and the physical vibration of his vehicle.

• Reflective markers are used as travel lane dividers, to mark the central reservation (median) or to mark exit slip-roads. Incorporating a raised retro-reflective element, they are typically more visible at night and in inclement weather than standard road marking lines. The color of markers varies depending on the country of use. Reflective markers are also referred to as raised pavement markers, road studs, and sometimes (generically) in the UK and Ireland as cat's eye, although this name refers to one particular brand of product. These markers can be used for other purposes such as marking the locations of fire hydrants (blue) or at gates of gated communities to indicate that emergency service vehicles have a code or device that allows them to open the gate. In the United Kingdom and elsewhere, raised markers are used to mark crosswalks (crossings) to assist the blind in crossing streets. In colder climates, reflective markers may be installed below ground using an elongated narrow triangle, cut into the road surface that allows the device to be installed below the road surface. Newer technology allows these to be placed above ground with snowploughable rails that attempt to protect the reflective components from the snowplough blade.

Non-mechanical markers

Paint

Paint, sometimes with additives like reflective glass beads, is generally used to mark travel lanes. It is also used to mark spaces in parking lots or special purpose spaces for handicap parking, loading zones, or time restricted parking areas. Colors for these applications vary by locality. Paint is a low-cost marking and has been in widespread use since approximately the early 1950s.

Paint is usually applied right after the road has been paved. The road is marked commonly by a truck called a "Striper." These trucks contain hundreds of gallons of paint stored in huge drums which sit on the bed. The markings are controlled manually or automatically by the controller who sits on the bed. Paint is run through a series of hoses under air pressure and applied to the roadway surface along with the application of reflective glass beads. After application, the paint dries fairly quickly.

Painted symbols, such as turn-lane arrows or HOV lane markers, are applied manually using templates.

Thermoplastic

One of the most common types of road marking based on its balance between cost and performance longevity, thermoplastic binder systems are generally based on one of three core chemistries: hydrocarbons, rosin esters or maleic modified rosin esters (MMRE). Thermoplastic coatings are generally homogeneous dry mixes of binder resins, plasticizers, glass beads (or other optics), pigments and fillers. Their usage has increased over paints mainly due to the performance benefits of increased durability, retro-reflectivity and a lack of VOC solvents.

Thermoplastic markings are applied using specially designed vehicles. The thermoplastic mix is heated the trucks to about 200°C before being fed to the application apparatus. This is often a screed box or ribbon gun. Immediately after the thermoplastic has been applied, glass beads are laid onto the hot material so that they embed before the plastic hardens. These beads provide initial retro-reflection. As the marking wears during use and the initial beads are lost, the beads mixed with the binder are uncovered, providing long term reflectivity. Most thermoplastic is produced in white and yellow colors, but other colors such as red can also be produced.

Plastic

were introduced in the late 1960s and early 1970s. Commonly referred to as "tape" or "cold plastic," this product is heavy-grade material with reflective beads embedded in the plastic. It is commonly used to mark crosswalks, stop bars and traffic guidances such as turn lane, HOV lanes, train crossing, pedestrian crossings, taxi lanes, bus lanes, and bike lanes. There are three ways to apply tape:

• Overlay - The application being laid over the surface of the pavement. Using industrial-grade rubber cement, once the tape is combined with the pavement, it should last three years. Major obstacles to estimated life are snow-plows, salt, and mis-application.
• Inlay - The tape physically becomes part of the asphalt. Using the heat generated in the paving process, road workers lay special tape on the asphalt in the hardening process, and rollers compress the two together.
• Hot Tape - This is the oldest method and is widely disappearing. During the process, the road worker lays out pre-manufactured shapes in the design required. Once in place, a torch is used to melt the plastic on the surface of the road. This is a slower process and more prone to a dull, burnt color of the finished product.

Epoxy

Epoxy has been in use since the late 1970s and has gained popularity over the 1990s as the technology has become more affordable and reliable. This material competes directly with plastic with respect to usage and cost.

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 road surface. A good example of this type of use is the Golden Gate Bridge in San Francisco.

Country specific information

United States

In the U.S., the type, placement, and graphic standards of traffic signs and road surfaces are legally regulated — the Federal Highway Administration's Manual on Uniform Traffic Control Devices is the standard, although each state produces its own manual based upon the Federal manual.

Generally white lane markings indicate a separation between lanes traveling in the same direction while yellow markings indicate opposing traffic on the other side of the line. In some areas, such as Colorado, black material is applied on the surface before a shorter white line is painted. This improves the contrast of the marking against "white" concrete.

In California, Botts' dots are commonly used to mark lanes on most freeways. A large number of California cities also use Botts' dots on some (or all) major arterials. The notable exception is the City of Los Angeles, which cannot afford to maintain any raised lane markers due to its fiscal problems, and uses only paint.

In California and Nevada, the reflectors when present are usually the lines, and no paint is used for additional markings. Exceptions include: freeways built from white concrete where painted stripes are added to make the lanes more visible through sun glare, freeways built so wide that the risk of drifting is minimal (e.g., Interstate 5 in the Central Valley), and freeways in areas where it snows in the winter (since the snowplows would scrape off the Botts' Dots).

In general, single broken lines mean passing is allowed, single solid lines mean pass only to avoid a hazard, and double solid lines mean it is prohibited, as it often is in tunnels. On two-lane roads, a single broken centerline means that passing is allowed in either direction, a double solid centerline means passing is prohibited in both directions, and the combination of a solid line with a broken line means that passing is allowed only from the side with the broken line and prohibited from the side with the solid line.

Crosswalks are indicated at a minimum by a pair of white lines. On major boulevards, crosswalks are further highlighted by zebra stripes, which are large white rectangles in the crosswalk perpendicular to traffic. In order to maximize the longevity of zebra crossing stripes, they are usually applied to correspond with the portions of the lane on which the wheels of a car are not usually traveling, thereby reducing wear on the markings themselves.

Canada

Generally speaking, Canadian pavement marking standards are consistent with those used throughout the United States.

Yellow lines are used to separate traffic moving in opposite directions, and white lines are used to separate traffic moving in the same direction, and on the shoulders of paved roads. On one-directional roads, a yellow line appears on the left shoulder, and a white line on the right shoulder. Passing rules are denoted by dashed lines as in the United States. Orange painted lines are used when the direction of the road is altered temporarily for construction projects.

Broken lines that are wider and closer together than regular broken lines are called continuity lines. When you see continuity lines on your left side, it generally means the lane you are in is ending or exiting and that you must change lanes if you want to continue in your current direction. Continuity lines on your right mean your lane will continue unaffected.

In some areas, reflective markers recessed into the pavement are used, especially approaching curves in the road.

Ontario has several pavement marking test areas located in various parts of the province. Perhaps the most well known location is the eastbound lanes of Highway 401 near Belleville. Other test sites are located on Highway 60, West of Renfrew, Highway 28 east of Bancroft, and on Highway 37, South of Tweed. Pavement marking manufacturers from around the world supply a variety of materials for these sites to have their products evaluated and approved for use on provincial highways.

Western Europe

Several Western European countries reserve white for routine lane markings of any kind, except bus stops and similar things. However, for example Norway has yellow markings separating traffic directions. Many countries use yellow, orange or red to indicate when lanes are being shifted temporarily to make room for construction projects.

In the Netherlands, Germany, Sweden, and the UK, so-called "naked roads" have been trialled, whereby all visible road markings, kerbs, traffic lights, and signs are removed. When this was tested in Seend, a village in the UK county of Wiltshire, the county council reported that accidents fell by a third, with motorists' speed falling by an average of 5%. It has been suggested that naked roads force drivers to make eye contact with other road users, and that it is this nonverbal communication that is responsible for the reduction of accidents. Other have suggested that road markings, especially with middle marker, make the road look like a main road, triggering faster and more relaxed driving, while no marking makes the road look like a lower quality road.

United Kingdom

In the U.K., a broken white line in the direction of travel, where the gaps are longer than the painted lines, indicates the centre of the road and that there are no hazards specific to the design and layout of the road, ie no turnings, sharp bends ahead etc. A broken white line in which the gaps are shorter than the painted lines indicates an upcoming hazard, the proportion of white to black indicates the degree of hazard ie more white means more hazard.

A double solid white line indicates that the line may not be crossed, overtaking is permitted if it can be performed safely without crossing the line. Solid lines can be crossed in certain specific conditions (turn right, overtake a vehicle with a design speed of less than 10mph or when directed to do so by a police officer). A solid white line with a broken white line parallel to it indicates that crossing the line is allowed for traffic in one direction (the side closest to the broken line) and not the other.

Solid white lines are also used to mark the outer edges of a road.

A double yellow line (commonly known as just a "Double Yellow") next to the kerb means that no parking is allowed at any time, whilst a single yellow line is used in conjunction with signs to denote that parking is restricted at certain times. Double and single red lines mean that stopping is not allowed at any time or between certain times respectively.

On many roads in the UK, reflective devices known as cat's eyes are placed in the road. These devices reflect the light from a car's headlights back towards the driver in order to highlight features of the road in poor visibility or at night. The colour of cat's eyes differs according to their location. Those defining the division between lanes are white, red cat's eyes are placed along the hard shoulder of a motorway or sometimes dual carriageways and orange cat's eyes are placed along the edge of the central reservation (median). Green cat's eyes denote joining or leaving slip roads at junctions.

See the highwaycode for a complete description of UK road markings.

Zig-zag lines are painted on the street either side of a pedestrian crossing. Motorists should not overtake, wait or park in the vicinity [120514].

Australia

In Australia, white lines are generally used both to separate traffic flowing in the same direction and traffic flowing in opposite directions. Yellow lines are used to designate tram fairways, with dashed yellow lines indicating that vehicles may drive on the tram tracks but should not delay trams, and solid yellow lines indicating that vehicles may not drive on the tracks. If a tram turns through an intersection, a yellow line is used to show how far the tram hangs out to remind other drivers not to overtake it on the inside.

New Zealand

Although New Zealand follows the convention of a solid yellow line to indicate no passing on roads with two-way traffic, it uses long dashed white lines to indicate when passing against opposing traffic is allowed on two-lane roads and shorter ones to separate lanes going in the same direction.

See also

• Cat's eye
• Federal Highway Administration
• Raised pavement marker

References

External links

• U.S. Federal Highway Administration - Learn About Pavement Markings