Traffic
Traffic is the movement of vehicles and pedestrians along land routes.
Traffic laws govern and regulate traffic, while rules of the road include traffic laws and 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, cones, or signs. Traffic is often classified by type: heavy motor vehicle, other vehicle, 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.
Etymology and types
The word traffic originally meant "trade" and comes from the Old Italian verb trafficare and noun traffico, as well as the Middle French trafique. The origin of the Italian words is unclear. Suggestions include Catalan trafegar "decant", an assumed Vulgar Latin verb transfricare 'rub across', an assumed Vulgar Latin combination of trans- and facere 'make or do', Arabic tafriq 'distribution', and Arabic taraffaqa, which can mean 'seek profit'. Broadly, the term covers many kinds of traffic including network traffic, air traffic, marine traffic and rail traffic, but it is often used narrowly to mean only road traffic.Rules of the road
Rules of the road and driving etiquette are the general practices and procedures that road users are required to follow. These rules usually apply to all road users, though they are of special importance to motorists and cyclists. These rules govern interactions between vehicles and pedestrians. The basic traffic rules are defined by an international treaty under the authority of the United Nations, the 1968 Vienna Convention on Road Traffic. Not all countries are signatory to the convention and, even among signatories, local variations in practice may be found. There are also unwritten local rules of the road, which are generally understood by local drivers.As a general rule, drivers are expected to avoid a collision with another vehicle and pedestrians, regardless of whether or not the applicable rules of the road allow them to be where they happen to be.
In addition to the rules applicable by default, traffic signs and traffic lights must be obeyed, and instructions may be given by a police officer, either routinely or as road traffic control around a construction zone, accident, or other road disruption.
Directionality
Traffic heading in inverse ways ought to be isolated so as to not hinder each other's way. The most essential guideline is whether to utilize the left or right half of the street.Traffic regulations
In many countries, the rules of the road are codified, setting out the legal requirements and punishments for breaking them.In the United Kingdom, the rules are set out in the Highway Code, which includes not only obligations but also advice on how to drive sensibly and safely.
In the United States, traffic laws are regulated by the states and municipalities through their respective traffic codes. Most of these are based at least in part on the Uniform Vehicle Code, but there are variations from state to state. In states such as Florida, traffic law and criminal law are separate; therefore, unless someone flees the scene of an accident or commits vehicular homicide or manslaughter, they are only guilty of a minor traffic offense. However, states such as South Carolina have completely criminalised their traffic law, so, for example, one is guilty of a misdemeanor simply for travelling 5 miles over the speed limit.
Trail ethics (right of way)
are a set of informal rules for right of way for users of trails, including hikers, mountaineers, equestrians, cyclists, and mountain bikers.Organised traffic
Passage priority (right of way)
Vehicles often come into conflict with other vehicles and pedestrians because their intended courses of travel intersect, and thus interfere with each other's routes. The general principle that establishes who has the right to go first is called "right of way" or "priority". It establishes who has the right to use the conflicting part of the road and who has to wait until the other does so.Signs, signals, markings and other features are often used to make priority explicit. Some signs, such as the stop sign, are nearly universal. When there are no signs or markings, different rules are observed depending on the location. These default priority rules differ between countries, and may even vary within countries. Trends toward uniformity are exemplified at an international level by the Vienna Convention on Road Signs and Signals, which prescribes standardised traffic control devices for establishing the right of way where necessary.
Crosswalks are common in populated areas, and may indicate that pedestrians have priority over vehicular traffic. In most modern cities, the traffic signal is used to establish the right of way on the busy roads. Its primary purpose is to give each road a duration of time in which its traffic may use the intersection in an organised way. The intervals of time assigned for each road may be adjusted to take into account factors such as difference in volume of traffic, the needs of pedestrians, or other traffic signals. Pedestrian crossings may be located near other traffic control devices; if they are not also regulated in some way, vehicles must give priority to them when in use. Traffic on a public road usually has priority over other traffic such as traffic emerging from private access; rail crossings and drawbridges are typical exceptions.
Uncontrolled traffic
Uncontrolled traffic comes in the absence of lane markings and traffic control signals. On roads without marked lanes, drivers tend to keep to the appropriate side if the road is wide enough. Drivers frequently overtake others. Obstructions arecommon.
Intersections have no signals or signage, and a particular road at a busy intersection may be dominant – that is, its traffic flows – until a break in traffic, at which time the dominance shifts to the other road where vehicles are queued. At the intersection of two perpendicular roads, a traffic jam may result if four vehicles face each other side-on.
Turning
Drivers often seek to turn onto another road or onto private property. The vehicle's blinking turn signals are often used as a way to announce one's intention to turn, thus alerting other drivers. The actual usage of directional signals varies greatly amongst countries, although its purpose is to indicate a driver's intention to depart from the current flow of traffic well before the departure is executed.Turning towards the edge of the road closest to a vehicle usually requires a driver to look out only for pedestrians and bicyclists.
Turning towards the opposing edge of the road usually requires a vehicle to cross opposing traffic. In this scenario, a driver often must stop and wait for a gap to turn, and if stopped in a through lane, such a stop might cause inconvenience for vehicles following behind that do not wish to turn. This is why dedicated lanes and protected traffic signals for turning are sometimes provided.
On busier intersections where a protected lane would be ineffective or cannot be built, turning may be entirely prohibited, and drivers will be required to "drive around the block" in order to accomplish the turn. Many cities employ this tactic quite often; in San Francisco, due to its common practice, making three right turns is known colloquially as a "San Francisco left turn". Likewise, as many intersections in Taipei City are too busy to allow direct left turns, signs often direct drivers to drive around the block to turn.
Turning rules are by no means universal. For example, in New Zealand between 1977 and 2012, left turning traffic had to give way to opposing right-turning traffic wishing to take the same road. New Zealand abolished this particular rule on 25 March 2012, except at roundabouts or when denoted by a Give Way or Stop sign. Although the rule caused initial driver confusion, and many intersections required or still require modification, the change is predicted to eventually prevent one death and 13 serious injuries annually.
On roads with multiple lanes, turning traffic is generally expected to move to the lane closest to the direction they wish to turn. For example, traffic intending to turn right will usually move to the rightmost lane before the intersection. Likewise, left-turning traffic will move to the leftmost lane. Exceptions to this rule may exist where for example the traffic authority decides that the two rightmost lanes will be for turning right, in which case drivers may take whichever of them to turn. Traffic may adapt to informal patterns that rise naturally rather than by force of authority. For example, it is common for drivers to observe the turn signals used by other drivers in order to make turns from other lanes. If several vehicles on the right lane are all turning right, a vehicle may come from the next-to-right lane and turn right as well, in parallel with the other right-turning vehicles.