Editing Traffic (section)

===Overtaking===
{{main|Overtaking}}

''Overtaking'' (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.

In the United Kingdom and Canada, notably on extra-urban roads, a solid white or yellow line closer to the driver is used to indicate that no overtaking is allowed in that lane. A double white or yellow line means that neither side may overtake.

In the United States, a solid white line means that lane changes are discouraged and a double white line means that the lane change is prohibited.

====Lanes====
<!--This section is linked from [[Driving on the left or right]].-->
[[File:Changing lanes in Gothenburg ubt.ogv|thumb|300px|right|Changing lanes on an 8-lane road outside [[Gothenburg]], Sweden]]
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 (geometry)|parallel]] corridors of traffic. Some roads have one lane for each direction of travel and others have multiple lanes for each direction. Most countries apply pavement markings to clearly indicate the limits of each lane and the direction of travel that it must be used for. In other countries lanes have no markings at all and drivers follow them mostly by [[Intuition (knowledge)|intuition]] rather than visual stimulus.

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. Driving cultures vary greatly on the issue of "lane ownership": in some countries, drivers traveling in a lane will be very protective of their right to travel in it while in others drivers will routinely expect other drivers to shift back and forth.

'''Designation and overtaking'''

The usual designation for lanes on [[divided highway]]s 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 with more traffic congestion all lanes are often used.

When [[Left- and right-hand traffic#Left-hand traffic|driving on the left]]:

* The lane designated for faster traffic is on the right.
* The lane designated for slower traffic is on the left.
* Most freeway exits are on the left.
* Overtaking is permitted to the right, and sometimes to the left.

When [[Left- and right-hand traffic#Right-hand traffic|driving on the right]]:

* 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.

Countries party to the [[Vienna Convention on Road Traffic]] have uniform rules about overtaking and lane designation.  The convention details (amongst other things) that "Every driver shall keep to the edge of the carriageway appropriate to the direction of traffic", and the "Drivers overtaking shall do so on the side opposite to that appropriate to the direction of traffic", notwithstanding the presence or absence of oncoming traffic. Allowed exceptions to these rules include turning or heavy traffic, traffic in lines, or situation in which signs or markings must dictate otherwise. These rules must be more strictly adhered to on roads with oncoming traffic, but still apply on multi-lane and divided highways. Many countries in Europe are party to the Vienna Conventions on traffic and roads. In Australia (which is not a contracting party), traveling in any lane other than the "slow" lane on a road with a speed limit at or above {{convert|80|km/h|abbr=on}} is an offence, unless signage is posted to the contrary or the driver is overtaking.

Many areas in North America do not have any laws about staying to the slowest lanes unless overtaking. In those areas, unlike many parts of Europe, traffic is allowed to overtake on any side, even in a slower lane. This practice is known as "passing on the right" in the United States and "overtaking on the inside" and "undertaking" in the United Kingdom.
When referring to individual lanes on dual carriageways, one does not consider traffic travelling the opposite direction. The inside lane ([[Overtaking#Rules of overtaking|in the British English sense]], i.e. the lane 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 lanes.

'''U.S.-state-specific practices'''

In some US states (such as [[Louisiana]], [[Massachusetts]] and [[New York City|New York]]), although there are laws requiring all traffic on a public way to use the right-most lane unless overtaking, this rule is often ignored and seldom enforced on multi-lane roadways.  Some states, such as [[Colorado]], use a combination of laws and signs restricting speeds or vehicles on certain lanes to emphasize overtaking only on the left lane, and to avoid a psychological condition commonly called [[road rage]].

In California, cars may use any lane on multi-lane roadways. Drivers moving slower than the general flow of traffic are required to stay in the right-most lanes (by [[California Vehicle Code]] (CVC) 21654) to keep the way clear for faster vehicles and thus speed up traffic. However, faster drivers may legally pass in the slower lanes if conditions allow (by CVC 21754). But the CVC also requires trucks to stay in the right lane, or in the right two lanes if the roadway has four or more lanes going in their direction. The oldest freeways in California, and some freeway interchanges, often have ramps on the left, making signs like "[[TRUCKS OK ON LEFT LANE]]" or "TRUCKS MAY USE ALL LANES" necessary to override the default rule. [[Lane splitting]], or riding motorcycles in the space between cars in traffic, is permitted as long as it is done in a safe and prudent manner.<ref>{{cite web | url=http://www.whybike.com/motorcycle274.htm | last=WhyBike? | title=All the info you need on lanesharing (lanesplitting) | date=6 March 2006}}</ref>