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Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.
Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !
Change the target language to find translations.
Tips: browse the semantic fields (see From ideas to words) in two languages to learn more.
||The examples and perspective in this article deal primarily with English-speaking territories and do not represent a worldwide view of the subject. (April 2011)|
Road surface marking is any kind of device or material that is used on a road surface in order to convey official information. They can also be applied in other facilities used by vehicles to mark parking spaces or designate areas for other uses.
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 standardize such markings across borders. However, countries and areas categorize and specify 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. Road surface marking can also indicate regulation for parking and stopping.
There is continuous effort to improve the road marking system, and technological breakthroughs include adding reflectivity, increasing longevity, and lowering installation cost.
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 in 1911. The first highway centerline was painted along M-15 (later a section of US Highway 41 or M-28) in 1917, by Kenneth Ingalls Sawyer, a claim supported by the Federal Highway Administration. 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 and some states already offering the double and single solid yellow center line). The changeover to the 1971 MUTCD standards took place between 1971 and 1975 with most done by the end of 1973, so for two years drivers still had to use the old and new. 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 simple mnemonic device 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 twentieth 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.
The line was put down as an experiment as there were a lot of accidents there, even in the early days of the motor car. The experiment proved to be so successful that the whole country adopted it as a standard road safety device, and later foreign countries put white line on their roads, too.
Mechanical devices may be raised or recessed into the road surface, and either reflective or non-reflective. Most are permanent; some are movable.
Paint, sometimes with additives such as 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 stencils.
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 use 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 in trucks to about 200 °C (400 °F) 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 may also be produced.
Plastics 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 guidance such as turn lanes, HOV lanes, train crossings, pedestrian crossings, taxi lanes, bus lanes, and bike lanes. There are three ways to apply tape:
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.
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.
In Australia, white lines are generally used both to separate traffic flowing in the same direction and traffic flowing in opposite directions. Double solid white center-lines may not be crossed under any circumstances, unless avoiding an obstruction. Dashed lines may be crossed for overtaking, changing lanes or turning, and also in the case of double-line markings provided the dashed line is on your side of the markings. For this reason dashed lines are usually used to mark multiple lanes traveling in the one direction. Yellow lines along road edges are used nationally to indicate "No Standing" areas not otherwise marked by signs. Solid white lines are also used to indicate kerbside parking, pedestrian and bicycle lanes, and other kerbside features. Yellow line markings are also used in areas that receive regular annual snowfall to provide contrast. Double-line markings are used to separate traffic flowing in opposite directions on busy roads.
Solid white lines are used to mark an intersection that a driver must stop at before entering whilst obeying all Right of Way laws. Dashed white lines are used to mark an intersection at which a driver must Give Way. Dashed white lines are also commonly used to indicate turns in intersections and to indicate intersections where a Diamond Turn is possible (intersections in which two cars traveling in opposite directions turn to the same direction-of-travel as each other without coming into contact).
Materials used are waterborne paint, thermoplastics, and cold applied plastic (PMMA), all with glass bead. Bead is generally 1mm for longitudinal marking. Currently moving to performance specified contracts with the primary performance indicator being retro-reflectivity measured with 30 metre geometry instruments. Intervention levels vary generally from 100 - 150 mcd/lux/m2.
DPI Thermoplastic road marking materials (DPI in short of Dura Product Industries) are a well-known name for producing highest quality thermoplastics in true white colour and other required colours.
|This section requires expansion. (January 2009)|
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 sometimes used when the direction of the road is altered temporarily for construction projects. However, the colour scheme was reversed before 1971, when white formerly used to denote the separation of opposing traffic, and yellow lines, when used, to denote the separation of the paved road from the right-hand shoulder.
Broken lines that are wider and closer together than regular broken lines are called continuity lines. Continuity lines on the left side of a lane denote that the lane is about to end and that motorists must soon merge left. Continuity lines on the right mean that the lane will continue, but traffic may merge into it ahead.
In some areas, reflective markers (cat's eyes) 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 the westbound lanes on Highway 417, east of Ottawa, Highway 60 West of Renfrew, Highway 28 east of Bancroft, Highway 69 North of Honey Harbour 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.
White lines separate lanes in same direction and yellow lines separate lanes in different directions.
Japan uses a scheme similar in some ways to North American markings, but with some differences. White always separates traffic in the same direction or indicates traffic in the same direction can use a buffered area that is striped in crosshatch patterns such as at right turns on two-way roads since Japan is a country that has left-side driving.
White is also used on divided expressways with a solid raised center divider, two-lane expressways where poles are the only physical barrier between opposing directions of travel always have yellow either side of the row of poles. White is between the yellow striping and the poles.
White is also used to denote passing allowed on other two-lane roads. Yellow indicates no passing is allowed. On all roads, yellow stripes are always solid.
On expressways where there are many sharp turns and curves, seen especially in the largest cities, a yellow line indicates no passing between lanes, as follows:
Solid yellow beside solid white: no entry permitted from the lane the stripe is next to, but passing is permitted with caution.
Solid yellow beside broken white: passing is permitted from the side with the broken white line, but not from the side with the yellow line.
Solid yellow line alone: passing prohibited from either lane, used on very tight curves and in tunnels.
Other markings include in the cities, destination and exit names painted in the lanes, which is done due to the very close proximity of exits, where in many cases it would be impractical to put up many overhead signs, although these are often seen approaching exits, a curved or slanted arrow points to the side of the expressway the exit will be on. A straight arrow following characters indicates the destination of the expressway.
Where a solid white line appears between lanes, passing is generally allowed but with caution.
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. The New Zealand convention followed the USA MUTCD convention common between 1961 and the early seventies.
Road markings in Hong Kong is basically identical with the United Kingdom, with longer dashed white lines to indicate lanes of opposing traffic, and shorter dashed white lines for lanes in the same direction. Solid double white lines are used to indicate that drivers are not permitted to change lanes. A solid white line with a broken white line indicates that crossing the line is allowed from the lane closer to the broken line. Double solid white lines are in place in all tunnels and underpasses.
As in the UK, solid yellow lines are painted along the kerbside to indicate that no parking is allowed, with double solid yellow lines meaning no parking is allowed at all times. Zig-zag lines are used on both ends of zebra crossings. Road studs are also used as in the UK.
During the World War II the Pedestrians Association lobbied for the government to make it safer for pedestrians to walk during the black out. As a result white lines were painted on the sides of the road and pedestrians were allowed to use a small torch.
In the U.K. The first "white line" road markings appeared on a number of dangerous bends on the London-Folkeston road at Ashford, Kent, in 1914, and during the 1920s the rise of painted lines on UK roads grew dramatically. In 1926 official guidelines were issued by the Ministry of Transport that defined where and how white lines on roads should be used. 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, i.e. 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 i.e. more white means more hazard.[not in citation given]
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 (entering premises, overtaking a stationary vehicle, overtaking a vehicle, pedal cycle or horse travelling at less than 10 mph, 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, retro-reflective road studs, generally known as "cat's eyes" when referring to the Halifax type road stud, 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 road studs differs according to their location. Those defining the division between lanes are white, red road studs are placed along the hard shoulder of motorways and dual carriageways and orange road studs are placed along the edge of the central reservation (median). Green road studs denote slip roads at grade-separated junctions.
Comprehensive information about highway markings in the UK are contained in The Traffic Signs Manual Chapter 5 .
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 arterial roads. The notable exception is the city of Los Angeles which only uses 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 or lane changing is allowed, single solid white lines mean lane changing is discouraged but not prohibited, and double solid white lines mean it is prohibited, as it often is in tunnels. On two-lane roads, a single broken center line means that passing is allowed in either direction, a double solid center line 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.
Marked 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.
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, curbs, 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.
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