Lane Information
A lane is a part of the roadway (British: carriageway) within a road marked out for use by single line of vehicles to the control and guide drivers so reduce conflicts. Most public roads (highways) have at least two lanes, one for traffic in each direction separated by Lane markings. Major highways often have two roadways separated by a median, each with multiple lanes. A single-track road carries traffic in both directions within a single lane with passing places to allow vehicles to pass. In North America and Australia, the term also may refer to rear access roads which act as a secondary vehicular network in cities and towns. Some urban streets are still called lanes, for example Drury Lane in London. A minor rural road may be referred to as a country lane.
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Types of lanes
A wild hare on a country lane in England At 18 through lanes wide, Highway 401 is one of the widest and busiest freeways in the world. Changing lanes on an 8-lane road in Gothenburg, Sweden- A traffic lane or travel lane is a lane for the movement of vehicles traveling from one destination to another, not including shoulders and auxiliary lanes.
- A through lane or thru lane is a traffic lane for through traffic. At intersections, these may be indicated by arrows on the pavement pointing straight ahead.
- A carriageway (Great Britain), roadway (United States) is a group of two or more lanes on a single paved surface. A rural 2-lane highway is usually built on a single surface with traffic in both directions, while large highways can be built with two (sometimes more) of these separated by buffers such as medians and barriers. On such highways, the lanes in each group usually travel in the same direction.
- A deceleration lane is a paved or semi-paved lane adjacent to the primary road or street. It is used to improve traffic safety by allowing drivers to pull off the main road and decelerate safely in order to turn (e.g. right in the United States or left in Great Britain), so that the traffic behind the turning vehicle is not slowed or halted. Deceleration lanes are primarily found in suburban settings.
- A fire lane is the area next to a curb, which is reserved for firefighting equipment, ambulances, or other emergency vehicles. Parking in these areas, often marked by red lines, usually warrants a parking ticket.
- A loading lane (loading zone in the United States) is an area next to a curb, which is reserved for loading and unloading passengers and/or freight. It may be marked by a sign ("LOADING ONLY" or "LOADING ZONE") or by a yellow or white-painted curb.
- A passing lane is often provided on steep mountain grades, in order to allow smaller vehicles to pass larger, slower ones. This is sometimes called a climbing lane if on the uphill side. (See truck lane below). Passing lanes may also be provided on long stretches of other roadway. On two-lane roads, using the lane of oncoming traffic as a passing lane is sometimes allowed given a long enough straightaway. In many countries permission is indicated by a broken line on the same side of the centerline as the vehicle intending to pass.
- A collector lane of a road is used for slower moving traffic and has more access to exits/off ramps.
- An express lane of a road is used for faster moving traffic and has less access to exits/off ramps. In other areas, an express lane may refer to a HOV lane (see below).
- A transfer lane of a road is used to move from express lanes to collector lanes, or vice-versa; it is somewhat similar to an auxiliary lane.
- A merge lane is a lane or onramp used to merge two flows of traffic into one, with the merge lane being the lane that disappears at the end of the merging area. Merge lane lengths depend mainly on the speed differential of the two merging flows, as the slower flow has to use the lane to accelerate.
- An auxiliary lane along a highway or motorway connects slip roads, with the entrance ramp or acceleration lane from one interchange leading to the exit ramp or deceleration lane of the next.
- The emergency lane of a road (also known as the breakdown lane, shoulder or hard shoulder) is reserved for breakdowns, and for emergency vehicles. The inner boundary of the lane often features rumble strips in order to physically warn drowsy or inattentive drivers that they are drifting off the roadway. This feature is seen especially often on highways and motorways, where the minimally-stimulating and monotonous nature of high-speed driving at night increases the chances for driver disorientation and serious injury or death if an accident does take place.
- An HOV lane or carpool lane is reserved for carpooling. In the US, they may be marked with a diamond icon every few hundred feet (hence the nickname "diamond lane"), or separated from other lanes by double broken white lines, a continuous pair of double yellow lines, or just a single broken white line.
- A High-occupancy toll lane is a combination of an HOV lane and toll collection technology that allows drivers without passengers to use the HOV lane by paying a premium price for the privilege
- A turn lane is set aside for slowing down and making a turn, so as not to disrupt traffic. At a full intersection with a traffic light, turn lanes are used more to hold traffic until the light changes.
- A designated bicycle lane is a portion of the roadway or shoulder designated for the exclusive or preferential use of bicyclists. This designation is indicated by special word and/or symbol markings on the pavement and "BIKE LANE" signs.
- A bus lane is reserved for buses providing public transportation on a fixed route, sometimes with overhead catenary for trolleybuses. In some countries, bus lanes may also be used by some other traffic, such as taxis, bicycles and motorbikes.
- A reversible lane (contraflow lane in Hawaii) uses overhead lane light markers, signs, poles or barriers to indicate the current direction of travel. They are used to accommodate periods of high traffic flow, especially rush hour where the flow is predominantly in one direction, on roads that cannot be easily widened. One or more lanes are removed from the opposing flow and added to the peak flow. Outside peak hours, the lanes revert to their normal configuration, perhaps with a center turn lane. To reduce the chance of head-on accidents, a resting period of an hour is often employed when reversing a lane; no traffic is allowed in the lane during this time. Some roads use portable barriers or plastic poles that are manually rearranged by work crews before and after the peak period, others use both lights and on-street markings (broken double-yellow line) or overhead lights. In some areas, the term suicide lane became a common slang description for this design because many people ignore the traffic control devices. Because of their history of numerous accidents and collisions, reversible lanes are rarely used.
- A tram lane is a lane reserved for the use of buses, trams and taxicabs. It is usually encountered in cities with curbside tram network, such as Zagreb.
- A truck lane (United States) or crawler lane (Great Britain) is a lane provided on long and steep uphill stretches of high-speed roads to enhance the ability of vehicles which can maintain speed up the incline to pass those vehicles (usually heavy trucks) which cannot. In addition, these lanes are intended to optimize pavement performance and minimize pavement fatigue. The lane is marked only on the uphill stretch and usually a short distance afterward (for regaining speed). A truckway often allows longer box length; for instance, the Florida Turnpike allows 29.3 meter double trailer combinations, in contrast to normal Florida highways' 16.2 meter limit. Since the major cost of trucking is the fixed cost of the same trailer with its driver the cost per ton of operating with truckway size and weight allowances is 35 to 40 percent below the cost of operations on the non-truckways.[1]
- An operational lane or auxiliary lane is an extra lane on the entire length of highway between interchanges, giving drivers more time to merge in or out. The lane is created when an entrance ramp meets the highway, and drops out (with an "exit only" sign) to become the ramp at the next exit.[2]
- An overtaking lane is the lane furthest from the shoulder of a multi-lane carriageway/roadway (sometimes called the fast lane, although this is deprecated by the authorities).
- The slow lane is the lane nearest to the shoulder of a multi-lane carriageway/roadway. This usage leads to the phrase Life in the Slow Lane, used as the title of various books and songs.
- A driving lane is an area in a parking lot/car park in between parking spaces so that vehicles can drive into and out of the spaces.
- A farm lane, which typically is the private property of one or more landowners, provides access to rural dwellings and agricultural buildings. It may be paved with concrete, asphalt, tar macadam, water bound macadam, gravel, or nothing more than earth, compressed with use.
- The term country lane, by contrast, typically denotes a public rural road. Farm lanes connect properties to country lanes (or to main roads).
Lane width and capacity
The U.S. Interstate Highway System uses a 12-foot (3.7 m) standard for lane width. 11-foot (3.4 m) lanes are found to be acceptable by the Federal Highway Administration for automobile traffic, but as lane width decreases (9-foot (2.7 m) lanes are found in some areas) traffic capacity decreases.[3] A full-width freeway lane typically has a capacity of 2,000 cars per hour.[4]
In the United Kingdom, many lanes are found in the countryside, and most of these lanes are wide enough for one car at a time and often have a lay by for cars to pass. In general, European laws and road width vary per country, with the minimum widths of lanes being anywhere between 2.5 m to 3.25 m (thus comparable to US lanes).[5]
Lane markings
Main article: Road surface marking A typical rural American freeway (Interstate 5 in the Central Valley of California). Notice the yellow line on the left, the dashed white line in the middle, and the solid white line on the right. There is also a "rumble strip" on the shoulder, not easily seen in this view.Painted lane markings vary widely from country to country. In the United States, Canada and Norway, yellow lines separate traffic going opposite directions and white separates lanes of traffic traveling the same direction, but this is not the case in many European countries.
Medians or central reservations
Main article: Central reservationBesides a painted line, lanes of traffic moving in opposing directions can also be separated by any of the following:
- Grass strip or ditch
- A central turning lane that allows vehicles to turn into driveways or streets on the opposite side of the road without stopping traffic
- A wide paved area with special paint markings indicating that it should never be crossed
- Metal guard rail (or guide rail) affixed to metal or wooden posts
- Cable barriers
- Concrete barriers such as Jersey barriers
Such separations between opposing traffic are referred to as a median in American English and as a central reservation in British English.
Numbering of freeway lanes in California
Traffic reports in California often refer to accidents being "in the number X lane." The California Department of Transportation (Caltrans) assigns the numbers from left to right.[6] The far left passing lane is the number 1 lane. The number of the slow lane (closest to freeway onramps/offramps) depends on the total number of lanes, and could be anywhere from 2 to 6.
History
For much of human history, roads did not need lane markings because most people walked or rode horses at relatively slow speeds. Another reason for not using lane markings is that they are expensive to maintain.
When automobiles, trucks, and buses came into widespread use during the first two decades of the 20th century, head-on collisions became more common.
Without the guidance provided by lane markings, drivers in the early days often erred in favor of keeping closer to the middle of the road, rather than risk going off-road into ditches or trees. This practice often left inadequate room for opposing traffic.
There are two people who have been credited with the invention of lane markings. In 1911, Edward N. Hines, the chairman of the Road Commission of Wayne County, Michigan was trying to make roads safer. He supposedly came up with the idea of painting stripes to separate lanes of traffic after riding behind a milk truck that leaked milk onto the center of the road, leaving a stripe.
June McCarroll, a physician in Indio California started experimenting with painting lines on roads in 1917 after she was run off of a highway by a truck driver. In November 1924, after years of lobbying by Dr. McCarroll and her allies, California officially adopted a policy of painting lines on its highways. A portion of Interstate 10 near Indio has been named the Dr. June McCarroll Memorial Freeway in her honor.
By 1939, lane markings had become so popular that they were officially standardized throughout the United States, and they were soon copied worldwide.
See also
- Lane departure warning system
- Road surface marking
- Traffic directionality
- Green lane (road)
- Country lane
- Shoulder (road)
References
- ^ Samuel, Peter. "The Way Forward to the Private Provision of Public Roads". Street Smart: Competition, Entrepreneurship and the Future of Roads. pp. 516–517.
- ^ Kurumi's Field Guide to Interchanges - Glossary
- ^ http://safety.fhwa.dot.gov/geometric/mitigationstrategies/chapter3/3_lanewidth.htm
- ^ http://www.scientificamerican.com/article.cfm?id=why-do-traffic-jams-somet
- ^ http://www.eurotestmobility.net/eurotest.php?itemno=224&lang=EN
- ^ http://www.dot.ca.gov/hq/oppd/hdm/pdf/chp0060.pdf dot.ca.gov
Categories: Road infrastructure
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