Overtaking or passing is the act of one vehicle going past another slower moving vehicle, travelling in the same direction, on a road. The lane used for overtaking another vehicle is almost always a passing lane further from the road shoulder which is to the left in places that drive on the right and to the right in places that drive on the left.
== Rules of overtaking ==
Note: In British English the meanings of inside and outside lanes are the reverse of US English. So in Britain, overtaking is performed using the outside lane, in the US it is termed the inside lane. In both cases, it is a passing lane farther from the shoulder of the roadway. In the United Kingdom overtaking is prohibited by either a solid white line or double solid white line, whilst in Canada yellow lines are used in the same configuration.
On a single carriageway/undivided carriageway road, the lane used for overtaking is often the same lane that is used by oncoming traffic, and it is often only advisable to overtake on long straightaways with plenty of visibility. In some jurisdictions, the "overtaking zone" is indicated by a single broken centerline (yellow or white in most countries) if overtaking is allowed in either direction, or paired with a single solid line beside it to indicate there is no overtaking from the solid side. In the UK, the format of the centerline is not used to regulate overtaking, only to indicate whether crossing of the line is prohibited or permitted.
In the Republic of Ireland, many national primary roads were upgraded in the 1990s and 2000s to ''wide two lane'' road (two lane road with space for three lanes, in addition to hard shoulders) to allow more space for overtaking (a very common manoeuvre in a country that had little dual carriageway until the early 2000s). However, due to the deceptive perception of safety given by such roads, future upgrade projects are likely to be 2+1 road where traffic volume suits (a successful pilot installation was used on the N20 near Mallow, County Cork). This form of road is of similar profile to wide two lane, but includes a central crash barrier, and has three lanes, with an overtaking lane on one side or the other, alternating every 2 km. It has been used in Denmark and Sweden since the 1990s.
On a dual carriageway/divided carriageway highway/motorway or arterial road, any lane can be an overtaking lane though in many places (including Germany) undertaking (overtaking on the side furthest from the road centre line) is prohibited. Lanes are normally separated by broken lines (usually white) but may be a single solid white to indicate lane-changing is allowed but discouraged. Double lines indicate that lane-changing (for example to overtake) is prohibited, such as in tunnels or sometimes for HOV lanes and HOT lanes.
Overtaking in an HOV or HOT lane is usually illegal for cars that do not meet the HOV/HOT criteria, except when directed by the police.
A few places also use the one-broken/one-solid marking at slip roads/entrance ramps, to indicate to highway drivers that the new lane merges and does not continue, so they do not attempt to overtake in a lane that ends shortly. This is also used at other points where lanes merge.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』