A hard shoulder or simply shoulder is a reserved area alongside the verge of a road or motorway. Generally it is kept clear of all traffic. In the event of an emergency or breakdown, a motorist can pull into the hard shoulder to get out of the flow of traffic and obtain an element of safety. A hard shoulder also allows some extra flexibility should a motorist need to take evasive action, as it is a buffer area between the main thoroughfare and the edge of the road. Emergency vehicles such as ambulances and police cars may also use the shoulder to bypass traffic congestion. These uses lead to the alternate names breakdown lane and emergency lane. In Ireland, dashed yellow lines demarkate hard shoulders on non-motorways, as can be seen along this dual carriageway on the N11.The shoulder is usually slightly narrower than a full traffic lane. In some cases, particularly on old rural roadways, shoulders do not exist or are made of gravel rather than hard asphalt or concrete. These are known as soft shoulders in comparison. Because the road surface changes at that point, they are less safe if they need to be used for emergency maneuvers, so modern practice is to build a hard shoulder whenever possible. To save money, the hard shoulder is sometimes not paved to the same thickness as the through lanes, so if vehicles were to attempt to use it as a through lane regularly, it would rapidly deteriorate. The shoulder also often collects various bits of debris that can make driving there unsafe. Drivers will sometimes drift into the shoulder when being overtaken by passing vehicles, particularly on two-lane roads. However, it is extremely unsafe, as well as often illegal, to abuse the hard shoulder by 'undertaking' passing vehicles that are nearer the centre of the road. (Some roads and expressways have a hard shoulder that is of such a narrow width that 'undertaking' is impossible.) In some jurisdictions, buses are allowed to drive on the shoulder to pass traffic jams (some observers call this a crude form of bus rapid transit). Driving in this manner requires an extremely high level of attention, however. For instance, buses are allowed to drive on the shoulder in the Minneapolis-St. Paul region of Minnesota, but in most cases, the shoulder is only one foot (30 cm) wider than the buses themselves. In Ontario, Highway 403 had its shoulders between Hurontario Street and Erin Mills Parkway widened in 2003 so they serve a dual-purpose as bus lanes and accident lanes. In other cities, such as the Boston Metro Area, cars are allowed to use the shoulder as they would a normal lane during morning and evening rush hours. On many roads, the shoulder disappears for short periods, particularly near exits and sometimes when going across bridges where the cost savings outweigh the disadvantages of not having the shoulder. However, some roads have a narrow shoulder for significant distances. This makes it difficult for large vehicles to pull into the hard shoulder altogether. The Jingjintang Expressway in northeastern China is an example of this phenomenon. Its hard shoulder is 2.4 metres wide, which is not wide enough for some automobiles. As a result, some motorists are unable to fully exit the mainline when they need to pull over, so they end up in a position that is halfway in the rightmost lane and halfway in the hard shoulder. The result is often a traffic jam and occasionally something worse. The break in the shoulder line used by California to warn of upcoming freeway exits in foggy areasIn Ireland, the hard shoulder is demarcated by road markings in the form of a single dashed yellow line (solid line on motorways), possibly with the addition of yellow cat's eyes (green when a junction is upcoming and the shoulder is temporarily closing). In the USA, the right-hand shoulder is separated by a solid white line, and the left-hand shoulder (if the road is a divided highway) is separated from the main road by a solid yellow line. On freeways in foggy parts of California, there is an obvious break in the line of the shoulder before every exit; this is to help drivers find their exits in heavy fog. [edit] Hard shoulders in the United Kingdom Full width hard shoulders are usually provided only on motorways and are usually 3.3 metres wide, but there are exceptions. Some motorways do not have hard shoulders at all (for example the A6144(M) and the A57(M)) and there are a small number of dual carriageway A-roads which do possess hard shoulders (for example, parts of the A1, A2 and A27). Hard shoulders are always marked with a reflectorised solid white line which is 20 cm wide and is provided with a rumble strip. A line of red cat's eyes is also used, and is placed to the side of the line. Sometimes, a hard shoulder will be coloured differently (usually red) to that of the main carriageway lanes. This is sometimes because the hard shoulder has not been resurfaced recently. The red colouring of many shoulders is because red surfacing was cheaper than black when the surface was laid. Sometimes, hard shoulders are coloured red to make it stand out from the main carriageway (for example on many of the motorways in Lancashire.) On many modern non-motorway roads, a hard strip is provided. These are usually 1 metre wide, and are bounded by thinner solid white lines, and often without a rumble strip.

The shoulder of a road resembles the body part in that it is a transitional area between the high part and the low/steep part. In the case of the body it's the part between the neck and the arm; in the case of a road, it's the part between the crown/middle of the road and the low part - the ditch. The connection is lost nowadays since so few roads have a ditch beside them. Also bottles have shoulders - it's where the neck expands out to the body, resembling a human shoulder. The same word is used in expressions such as 'shoulder season', in the tourist trade - it's between the high season and the low (slow) season.

Here is a simple and brief answer: its called the shoulder, because it acts like a shoulder for automobiles to pull over, if it experiences mechanical difficulty. kind of like a safety zone. you may see a warning sign that says "low or no shoulder ahead". this means exactly what the sign says, the shoulder is out of commission and to use caustion. hope this helps, john

It is called shoulder because it is at the side of the road like the shoulder of our body which is at the side and not the middle.So the side portion of the road may be called as shoulder because of its location and not its purpose.