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A shoulder, often serving as an emergency stopping lane, is a reserved lane by the verge of a road or motorway, on the right in countries which drive on the right, or on the left side in those that drive on the left. Many wider U.S. freeways have shoulders on both sides of each directional carriageway, in the median as well as at the outer edges of the road, for additional safety. Typically the shoulder is not for use by moving traffic. Shoulders have multiple uses, including: * In the event of an emergency or breakdown, a motorist can pull into the shoulder to get out of the flow of traffic and obtain a greater degree of safety. * Emergency vehicles such as ambulances and police cars may use the shoulder to bypass traffic congestion. * Active traffic management, used on busy multi-lane roads, may allow 'hard shoulder running' by general traffic at reduced speeds during periods of high traffic volumes. * In some places a 'Bus bypass shoulder' may be provided which allows bus services to pass stationary traffic. * Paved shoulders provide additional space should a motorist need to take evasive action (such as avoiding a wrong-way driver) or need to recover control of their vehicle before a run-off-road collision occurs. * In some urban areas, shoulders are used as travel lanes during peak commuting hours. * In some rural areas without sidewalks, pedestrians and cyclists may be allowed to walk or ride on the shoulders. * On curbed roadways, shoulders move the gutter away from the travel lanes which reduces the risk of hydroplaning, and reduces splash and spray of stormwater onto pedestrians using any adjacent sidewalk. * Paved shoulders move water away from the roadway before it can infiltrate into the road's subbase, increasing the life expectancy of the road surface. * Shoulders help provide extra structural support of the roadway. ==General characteristics== The shoulder is usually slightly narrower than a full traffic lane. In some cases, particularly on older rural roadways, shoulders that initially existed were hardened with gravel rather than being paved with asphalt or concrete. In Britain, motorway shoulders are now paved, but are still known as 'hard shoulders.' Older, gravel shoulders have sometimes been termed soft shoulders by comparison. Because the paved surface ends at that point, they are less safe if they need to be used for emergency maneuvers. Notably, the section of Ontario Highway 401 between Windsor and London had soft shoulders with a sharp slope which was blamed for facilitating vehicle rollovers, if drivers accidentally drifted off of the paved section of the road and then overreacted after hitting the gravel. Modern practice is to build a continuous paved shoulder whenever possible.〔(Questia, Your Online Research Library )〕 The U.S. Federal Highway Administration encourages the placement of a ''Safety Edge'' — a 30° compacted taper on the end of the pavement dropoff — to ensure that any driver running off the edge of the roadway is better able to maintain control while trying to steer back onto the pavement. The Safety Edge is effective on roads where the shoulder is narrow nor nonexistent.〔(【引用サイトリンク】 Safety Edge Introduction - Every Day Counts )〕 To save money, the shoulder was often 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. In Britain, shoulder running can occur during roadworks, and full depth construction is now standard. In some metro areas, road authorities also allow shoulders to be used as lanes at peak periods. However, rural shoulders often collects various bits of road debris that can make driving there less safe. 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 illegal, to abuse the shoulder by 'undertaking' passing vehicles that are nearer the centre of the road. On older roads, the shoulder may disappear for short periods, near exits or when going across or under bridges or tunnels where the cost savings were thought to outweigh the safety benefits of the shoulder. 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 shoulder is only 2.4 metres wide, which is not wide enough for some automobiles. (A standard lane in the US and UK is 12 feet or 3.65 metres.) 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 only partly on the shoulder. The result is often a traffic jam and occasionally a collision. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Shoulder (road)」の詳細全文を読む スポンサード リンク
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