An all-way stop – also known as a four-way stop (or three-way stop etc. as appropriate) – is a traffic management system which requires vehicles on all the approaches to an road intersection to stop at the intersection before proceeding through it. Designed for use at low traffic-volume locations, the arrangement is common in the United States, Canada, South Africa, and Liberia, as well as in a number of, usually rural, locations in Ireland where visibility on the junction approaches is particularly poor. The stop signs at such intersections may be supplemented with additional plates stating the number of approaches.
In most jurisdictions of the United States, the rules of the all-way stop are the same. A motorist approaching an all-way stop is always required to come to a full stop behind the crosswalk or stop line. Pedestrians always have the priority to cross the road, even if the crosswalk is not marked with surface markings.
Driving instructors suggest that communication is always vital—including the use of turn signals to indicate which direction you intend to turn. Often, vehicles are able to make compatible moves at the same time without following the order listed above. If it is not clear who has the right-of-way, drivers should use judgement and communicate with hand-gestures until they clear the intersection. Within some U.S. jurisdictions, such as the state of Idaho, bicyclists are exempt from the need to make a complete stop, but must give way to other vehicles as otherwise required by law.
In the United States, the Federal Highway Administration's Manual on Uniform Traffic Control Devices (MUTCD) defines the standards commonly used for the application of all-way stops. Where a stop has been determined to qualify, it is signed at all approaches to the intersections with a standard octagonal "Stop" sign, with a supplemental "All-Way" plate. Earlier editions of the MUTCD allowed supplemental plates specifying the number of approaches in an all-way stop, as in "2-Way", "3-Way" or "4-Way". According to the MUTCD, installation of an all-way stop should be based on a traffic engineering study to determine if minimum traffic volume or safety criteria are met. These intersections are often found where roads have light-volume traffic which does not justify a traffic light.
An all-way stop may also be justified if the intersection has shown a history of collisions involving pedestrians or vehicles. All-way stops may also be used as an interim measure preceding the placement of a traffic light, to provide a low-speed area for pedestrians to cross, where a cross street experiences considerable difficulty finding safe gaps due to heavy traffic volumes, or where traffic is frequently delayed by turning conflicts. Additionally, the MUTCD advocates the placement of all-way stops at intersections between through roads in residential areas if an engineering study can show that traffic flow would be improved by installing it. Despite published guidelines, all-way stops are routinely placed by jurisdictions due to political pressure from adjacent residents. Intersections between two minor highways with similar traffic counts, two collector roads in an urban or suburban setting or a collector road and a local road in a busy setting (such as near a school) are the most common locations for an all-way stop.
Traffic signals will sometimes flash red indications in all directions following a malfunction, or all-red flashing operation may be scheduled to reduce delay or handle construction activity or unusual traffic patterns. When a traffic signal flashes in all-red mode, it legally operates as an all-way stop. When all approaches to an intersection are controlled in this way the rules for an all-way stop apply. However, it must also be noted that traffic signals may also flash yellow to major directions and flash red to minor directions during off-peak times to minimize traffic delays, in which case only side-street traffic is required to stop and yield the right of way to crossing traffic on the major street.
During electrical outages when a traffic signal does not display any indications including flashing red, some jurisdictions require that the intersection be treated as an all-way stop. Other jurisdictions treat a dark signal as an uncontrolled intersection, where standard rules of right-of-way apply without the requirement of a complete stop.
The main reason for the use of stop signs at road junctions is safety.:430 According to an international study of locations where the system is in use, all-way stop control applied to four-legged intersections may reduce accident occurrence by 45%.:431–432 However, given alternative methods of intersection control and some of the disadvantages of all-way stops, the Handbook of Road Safety Measures recommends that four-way stops are best used between minor roads away from urbanized areas.:431–433 Another benefit of all-way stops is assurance that vehicles enter the intersection at a low speed and have more time to take heed of the traffic situation,:430 especially useful when sight distance is highly restricted.
Some of the disadvantages associated with all-way stops are:
Few countries outside North America – least of all, those in Europe – have intersections at which all users must stop at all times; the conditions for stop sign placement may indeed preclude such an arrangement in many places.:430 In Sweden all-way stops (Flervägsstopp) have been tested since the 1980s but are little used even though they are now permitted. In the UK they have always been very uncommon and were formally prohibited by the Department for Transport in 2002.
At four-legged intersections within Europe, a roundabout or mini-roundabout is commonly used to assign a relative priority to each approach. (Roundabouts remain rare in North America, where early failures of rotaries and traffic circles caused such designs to lose favor until the gradual introduction of the modern roundabout in the late 20th century.) Alternatively, at smaller intersections, priority to the right is widely used in most countries with right-hand traffic.
The geometric design of roads is the branch of highway engineering concerned with the positioning of the physical elements of the roadway according to standards and constraints. The basic objectives in geometric design are to optimize efficiency and safety while minimizing cost and environmental damage. Geometric design also affects an emerging fifth objective called "livability," which is defined as designing roads to foster broader community goals, including providing access to employment, schools, businesses and residences, accommodate a range of travel modes such as walking, bicycling, transit, and automobiles, and minimizing fuel use, emissions and environmental damage.Geometric roadway design can be broken into three main parts: alignment, profile, and cross-section. Combined, they provide a three-dimensional layout for a roadway.
The alignment is the route of the road, defined as a series of horizontal tangents and curves.
The profile is the vertical aspect of the road, including crest and sag curves, and the straight grade lines connecting them.
The cross section shows the position and number of vehicle and bicycle lanes and sidewalks, along with their cross slope or banking. Cross sections also show drainage features, pavement structure and other items outside the category of geometric design.Indiana State Road 101
State Road 101 in the U.S. state of Indiana is a north–south state highway in the eastern portion of Indiana that exists in four sections with a combined length of 79.42 miles (127.81 km).Indiana State Road 120
State Road 120 (SR 120) is a state road in the north-eastern section of the state of Indiana. Running for about 60 miles (97 km) in a general east–west direction, connecting rural portions of Elkhart, Lagrange and Steuben counties. The western terminus is a junction with Jackson Boulevard and Middleton Run Road in Elkhart. The eastern terminus is at the Indiana–Michigan border, east of Fremont.
The modern route of SR 120 was originally just small part of a much longer Native American trail. In the early 1920s a project to construct a road replacing the Native American trail took place. SR 120 was introduced in 1937 routed along its current routing, as a state road number for Vistula Road, which was falling apart. The western end of SR 120 has been moved a couple of different times within the city of Elkhart.Indiana State Road 205
State Road 205 (SR 205) is a State Road in the north-eastern section of the state of Indiana. Running for roughly 32 miles (51 km) in a general northeast-southwest direction, it connects the cities and towns of South Whitley, Columbia City and Garrett via SR 327. SR 205 was originally introduced in the mid-1930s routed between South Whitley and Churubusco. The road was extended northeast to the intersection with SR 327 in the mid to late 1940s.Indiana State Road 63
State Road 63 (SR 63) in the U.S. state of Indiana is a north–south route in the western portion of the state. Until mid-2008, it covered a distance of just over 96 miles (154 km), but now is a discontinuous route. For 63 miles (101 km), from the city of Terre Haute until it rejoins U.S. Route 41 (US 41) near Carbondale, it is a four-lane divided highway and replaces US 41 as the major north–south artery in this portion of the state.Intersection (road)
This article primarily reflects practice in jurisdictions where vehicles are driven on the right. If not otherwise specified, "right" and "left" can be reversed to reflect jurisdictions where vehicles are driven on the left.
An intersection is an at-grade junction where two or more roads or streets meet or cross. Intersections may be classified by number of road segments, traffic controls, and/or lane design.Level crossing
A level crossing is an intersection where a railway line crosses a road or path, or in rare situations an airport runway, at the same level, as opposed to the railway line crossing over or under using an overpass or tunnel. The term also applies when a light rail line with separate right-of-way or reserved track crosses a road in the same fashion. Other names include railway level crossing, grade crossing, road through railroad, railroad crossing, train crossing, and RXR (abbreviated).Level of service
Level of service (LOS) is a qualitative measure used to relate the quality of motor vehicle traffic service. LOS is used to analyze roadways and intersections by categorizing traffic flow and assigning quality levels of traffic based on performance measure like vehicle speed, density, congestion, etc.Maryland Route 186
Maryland Route 186 (MD 186) is a state highway in the U.S. state of Maryland. Known as Brookville Road, the highway runs 1.52 miles (2.45 km) from Western Avenue at the District of Columbia boundary to MD 410 within Chevy Chase. MD 186 passes through an affluent, mainly residential area in its course through the many incorporated and unincorporated areas of Chevy Chase. Brookville Road once connected Tenleytown with what is now MD 97 north of Silver Spring. MD 186 was paved over most of its course by 1910. The northernmost part of the highway was paved when MD 410 was built in the late 1920s.Mississippi Highway 368
Mississippi Highway 368 (MS 368) is a state highway in northern Mississippi. The route starts at MS 2 and MS 15 in Blue Mountain and travels eastward from the town. The road intersects a few city streets inside the town and county roads outside it. MS 368 ends at its intersection with County Road 700 (CO 700). The route was designated around 1956, connecting MS 2 and MS 15 in Blue Mountain to MS 370 near Dumas. A western extension to MS 5 existed for ten years from 1957 to 1967, and the section east of CO 700 gradually returned to Tippah County for maintenance.Mississippi Highway 403
Mississippi Highway 403 (MS 403) is a state highway in central Mississippi. The route starts at U.S. Route 82 (US 82) and MS 15 in Mathiston, and it travels north away from the town. It then turns east near Natchez Trace Parkway and then travels below it. MS 403 ends at the intersection of Clarkson Road and Old US 82 near a county highway maintenance barn. The route was designated by 1960, after a paved road extending from Mathiston was constructed around 1958. An extension northwards to MS 50 and MS 341 existed from 1960 to 1967.Northeast blackout of 2003
The Northeast blackout of 2003 was a widespread power outage throughout parts of the Northeastern and Midwestern United States, and the Canadian province of Ontario on August 14–28, 2003, beginning just after 4:10 p.m. EDT.Some power was restored by 11 p.m. Most did not get their power back until two days later. In other areas, it took nearly a week or two for power to be restored. At the time, it was the world's second most widespread blackout in history, after the 1999 Southern Brazil blackout. The outage, which was much more widespread than the Northeast blackout of 1965, affected an estimated 10 million people in southern and central Ontario, and 45 million people in eight U.S. states.
The blackout's primary cause was a software bug in the alarm system at the control room of FirstEnergy, an Akron, Ohio–based company, which rendered operators unaware of the need to redistribute load after overloaded transmission lines drooped into foliage. What should have been a manageable local blackout cascaded into collapse of the entire Northeast region.Road signs in Sweden
Road signs in Sweden are regulated in Vägmärkesförordningen, VMF (2007:90), and are to be placed 2 metres from the road with the sign 1.6m from the base for motorized roads. Except for route numbers, there are a maximum of three signs on a pole, with the most important sign at the top. All signs have a reflective layer added on selected parts of the sign as is custom in European countries; most larger signs also have their own illumination.
Most signs are based on pictograms, with some exceptions like the prohibition-sign for stop at customs and signal and speed limit signs.
If the sign includes text, the text is written in Swedish, except the stop sign, which is written in English ("STOP").
Swedish road signs depict people with realistic (as opposed to stylized) silhouettes.Roundabout
A roundabout (also called a traffic circle, road circle, rotary, rotunda or island) is a type of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junction.Modern roundabouts observe various design rules to increase safety. Compared to stop signs, traffic signals, and earlier forms of roundabouts, modern roundabouts reduce the likelihood and severity of collisions greatly by reducing traffic speeds and minimizing T-bone and head-on collisions. Variations on the basic concept include integration with tram and/or train lines, two-way flow, higher speeds and many others.
Traffic exiting the roundabout comes from one direction, rather than three, simplifying the pedestrian's visual environment. Traffic moves slowly enough to allow visual engagement with pedestrians, encouraging deference towards them. Other benefits include reduced driver confusion associated with perpendicular junctions and reduced queuing associated with traffic lights. They allow U-turns within the normal flow of traffic, which often are not possible at other forms of junction. Moreover, since vehicles on average spend less time idling at roundabouts than at signalled intersections, using a roundabout potentially leads to less pollution. When entering vehicles only need to give way, they do not always perform a full stop; as a result, by keeping a part of their momentum, the engine will produce less work to regain the initial speed, resulting in lower emissions. Research has also shown that slow moving traffic in roundabouts makes less noise than traffic that must stop and start, speed up and brake.Modern roundabouts were first standardised in the UK in 1966 and were found to be a significant improvement over previous traffic circle and rotaries. Since then they have spread and modern roundabouts are commonplace throughout the world. Half of the world's roundabouts are in France (more than 30,000 as of 2008), although the United Kingdom has more as a proportion of the road than any other country.Stop sign
A stop sign is a traffic sign designed to notify drivers that they must come to a complete stop and make sure no other vehicles are coming and no pedestrians are crossing before proceeding.Traffic
Traffic on roads consists of road users including pedestrians, ridden or herded animals, vehicles, streetcars, buses and other conveyances, either singly or together, while using the public way for purposes of travel. Traffic laws are the laws which govern traffic and regulate vehicles, while rules of the road are both the laws and the informal rules that may have developed over time to facilitate the orderly and timely flow of traffic.
Organized traffic generally has well-established priorities, lanes, right-of-way, and traffic control at intersections.
Traffic is formally organized in many jurisdictions, with marked lanes, junctions, intersections, interchanges, traffic signals, or signs. Traffic is often classified by type: heavy motor vehicle (e.g., car, truck), other vehicle (e.g., moped, bicycle), and pedestrian. Different classes may share speed limits and easement, or may be segregated. Some jurisdictions may have very detailed and complex rules of the road while others rely more on drivers' common sense and willingness to cooperate.
Organization typically produces a better combination of travel safety and efficiency. Events which disrupt the flow and may cause traffic to degenerate into a disorganized mess include road construction, collisions, and debris in the roadway. On particularly busy freeways, a minor disruption may persist in a phenomenon known as traffic waves. A complete breakdown of organization may result in traffic congestion and gridlock. Simulations of organized traffic frequently involve queuing theory, stochastic processes and equations of mathematical physics applied to traffic flow.Traffic light
Traffic lights, also known as traffic signals, traffic lamps, traffic semaphore, signal lights, stop lights, robots (in South Africa, Zimbabwe and other parts of Africa), and traffic control signals (in technical parlance), are signalling devices positioned at road intersections, pedestrian crossings, and other locations to control flows of traffic.
The world's first traffic light was a manually operated gas-lit signal installed in London in December 1868. It exploded less than a month after it was implemented, injuring its policeman operator. Earnest Sirrine from Chicago patented the first automated traffic control system in 1910. It used the words "STOP" and "PROCEED", although neither word was illuminated.Traffic lights alternate the right of way accorded to users by illuminating lamps or LEDs of standard colours (red, amber (yellow), and green) following a universal colour code. In the typical sequence of colour phases:
The green light allows traffic to proceed in the direction denoted, if it is safe to do so and there is room on the other side of the intersection.
The amber light warns that the signal is about to change to red. In a number of European countries – among them the United Kingdom – a phase during which red and yellow are displayed together indicates that the signal is about to change to green. Actions required by drivers on a yellow light vary, with some jurisdictions requiring drivers to stop if it is safe to do so, and others allowing drivers to go through the intersection if safe to do so.
A flashing amber indication is a warning signal. In the United Kingdom, a flashing amber light is used only at pelican crossings, in place of the combined red–amber signal, and indicates that drivers may pass if no pedestrians are on the crossing.
The red signal prohibits any traffic from proceeding.
A flashing red indication requires traffic to stop and then proceed when safe (equivalent to a stop sign).In some countries traffic signals will go into a flashing mode if the conflict monitor detects a problem, such as a fault that tries to display green lights to conflicting traffic. The signal may display flashing yellow to the main road and flashing red to the side road, or flashing red in all directions. Flashing operation can also be used during times of day when traffic is light, such as late at night.Traffic stop
A traffic stop, commonly called being pulled over, is a temporary detention of a driver of a vehicle by police to investigate a possible crime or minor violation of law.Traffic violations reciprocity
Under traffic violations reciprocity agreements, non-resident drivers are treated like residents when they are stopped for a traffic offense that occurs in another jurisdiction. They also ensure that punishments such as penalty points on one's license and the ensuing increase in insurance premiums follow the driver home. The general principle of such interstate, interprovincial, and/or international compacts is to guarantee the rule "one license, one record."
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