Traffic on roads
Traffic laws are the laws which govern traffic and regulate vehiclesTraffic 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.
Vehicles often come into conflict with other vehicles and pedestriansVehicles 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 standardized traffic control devices (signs, signals, and markings) for establishing the right of way where necessary.
Crosswalks (or pedestrian crossings) are commonCrosswalks (or pedestrian crossings) 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 organized 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 comes in the absence of lane markings and traffic control signalsUncontrolled 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 are common.
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.
Intention to turnDrivers will often want to cease to travel a straight line and turn onto another road or onto private property. The vehicle's directional signals (blinkers) are often used as a way to announce one's intention to turn, thus alerting other drivers. The actual usage of blinkers varies greatly amongst countries, although its purpose should be the same in all countries: to indicate a driver's intention to depart from the current (and natural) flow of traffic well before the departure is executed (typically 3 seconds as a guideline).
This will usually mean that turning traffic will have to stop in order to wait for a breach to turn, and this might cause inconvenience for drivers that follow them but do not want to turn. This is why dedicated lanes and protected traffic signals for turning are sometimes provided.
"Four-way" intersectionsPerpendicular intersections Also known as a "four-way" intersection, this intersection is the most common configuration for roads that cross each other, and the most basic type.
If traffic signals do not control a 4-way intersection, signs or other features are typically used to control movements and make clear priorities. The most common arrangement is to indicate that one road has priority over the other, but there are complex cases where all traffic approaching an intersection must yield and may be required to stop.
In the United States, South Africa, and Canada, there are four-way intersections with a stop sign at every entrance, called four-way stops. A failed signal or a flashing red light is equivalent to a four-way stop, or an all-way stop.
Rules for four-way stopsSpecial rules for four-way stops may include:
In the countries that use four-way stops, pedestrians always have priority at crosswalks - even at unmarked ones, which exist as the logical continuations of the sidewalks at every intersection with approximately right angles - unless signed or painted otherwise.
Whichever vehicle first stops at the stop line - or before the crosswalk, if there is no stop line - has priority.
If two vehicles stop at the same time, priority is given to the vehicle on the right.
If three vehicles stop at the same time, priority is given to the two vehicles going in opposite directions, if possible.
If four vehicles stop, drivers usually use gestures and other communication to establish right-of-way.
PedestriansPedestrians must often cross from one side of a road to the other, and in doing so may come into the way of vehicles traveling on the road. In many places pedestrians are entirely left to look after themselves, that is, they must observe the road and cross when they can see that no traffic will threaten them. Busier cities usually provide pedestrian crossings, which are strips of the road where pedestrians are expected to cross.
The actual appearance of pedestrian crossings varies greatly, but the two most common appearances are: (1) a series of parallel white stripes or (2) two long horizontal white lines. The former is usually preferred, as it stands out more conspicuously against the dark pavement.
Traffic signalsSome pedestrian crossings also accompany a traffic signal which will make vehicles stop at regular intervals so the pedestrians can cross. Some countries have "intelligent" pedestrian signals, where the pedestrian must push a button in order to assert his intention to cross. The traffic signal will use that information to schedule itself, that is, when no pedestrians are present the signal will never pointlessly cause vehicle traffic to stop.
Pedestrian crossings without traffic signals are also common. In this case, the traffic laws usually states that the pedestrian has the right of way when crossing, and that vehicles must stop when a pedestrian uses the crossing.
The higher the speed of a vehicle, the more difficult collision avoidance becomesThe higher the speed of a vehicle, the more difficult collision avoidance becomes and the greater the damage if a collision does occur. Therefore, many countries of the world limit the maximum speed allowed on their roads. Vehicles are not supposed to be driven at speeds which are higher than the posted maximum.
To enforce speed limits, two approaches are generally employed. In the United States, it is common for the police to patrol the streets and use special equipment (typically a radar unit) to measure the speed of vehicles, and pull over any vehicle found to be in violation of the speed limit
OvertakingOvertaking (or passing) refers to a maneuver by which one or more vehicles traveling in the same direction are passed by another vehicle. On two-lane roads, when there is a split line or a dashed line on the side of the overtaker, drivers may overtake when it is safe. On multi-lane roads in most jurisdictions, overtaking is permitted in the "slower" lanes, though many require a special circumstance. See "Lanes" below.When a street is wide enough to accommodate several vehicles traveling side-by-side, it is usual for traffic to organize itself into lanes, that is, parallel corridors of traffic. Some roads have one lane for each direction of travel and others have multiple lanes for each direction.On roads that have multiple lanes going in the same direction, drivers may usually shift amongst lanes as they please, but they must do so in a way that does not cause inconvenience to other drivers.
Reckless drivingReckless driving is often defined as a mental state in which the driver displays a wanton disregard for the rules of the road; the driver often misjudges common driving procedures, often causing accidents and other damages. Reckless driving has been studied by who found that reckless drivers score high in risk-taking personality traits. However, no one cause can be assigned to this state. There are some states, such as Virginia, where mental state is not considered, but rather a set of specific violations can be deemed reckless. Excessive speed by itself is sufficient for a reckless driving conviction in some jurisdictions (e.g., Virginia).
OvertakingDesignation and overtaking The usual designation for lanes on divided highways is the fastest lane is the one closest to the center of the road, and the slowest to the edge of the road. Drivers are usually expected to keep in the slowest lane unless overtaking, though all lanes are often used.The lane designated for faster traffic is on the left.
The lane designated for slower traffic is on the right.
Most freeway exits are on the right.
Overtaking is permitted to the left, and sometimes to the right.. When referring to individual lanes on dual carriageways, one does not consider traffic travelling the opposite direction. The inside lane (i.e. the one beside the hard shoulder) refers to the lane used for normal travel, while the middle lane is used for overtaking cars on the inside lane. The outside lane (i.e. closest to oncoming traffic) is used for overtaking vehicles in the middle lane. The same principle lies with dual carriageways with more than three