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In road transportation in the United States, a special route is a prefixed and/or suffixed numbered road that forms a loop or spur of a more dominant route of the same route number and system. The dominant route is generally referred to as the "parent" or "mainline", while special routes are also unofficially or neologistically known as child routes or auxiliary routes. Special routes are included in many highway systems in the United States; most are found in the Interstate Highway System, U.S. highway system, and various state highway systems. There are numerous types of special routes, each possessing generally defined characteristics and having defined relationships with the parent route. Types of special routes: Business Route, Scenic Route, Truck Route, Spur Route, Alternate Route, Bypass Route, Connector Route, Toll Route, Temporary Route, Loop Route, Permanently signed detour route, and Divided Route (see List of divided U.S. Routes) ==Nomenclature== In the field, the special route is typically distinguished from the parent route with the use of auxiliary words or suffix letters placed on the route shield or on an adjacent sign, known as a "banner" or "plate" or according to the ''Manual on Uniform Traffic Control Devices'', a "route sign auxiliary sign". A common roadfan synonym for special route is "bannered highway" or "bannered route", terms coined from the presence of these companion signs. The term is not all-encompassing however, as not all special routes have these banners. The American Association of State Highway and Transportation Officials (AASHTO) sets the nationwide precedent for special routes, particularly for U.S. Numbered Highways. As of 2009, the standards organization only advocates four types of special routes: business, bypass, alternate, and temporary. AASHTO suggests that transportation authorities of the United States decommission other types of special routes and/or replace such obsolete designations with another type of route. Some old alignments of routes may also be informally known as special routes (despite some that do not intersect the parent route). These older alignments may be given street names like "Old U.S. Highway 52", or in some rare cases, be signed with route shields attached to "Old" or "Historic" banners (such as decommissioned sections of former U.S. Route 66 that are still driveable). In the case of U.S. state route systems, special routes are generally restricted to primary state routes, not secondary state routes, though Missouri has three supplemental routes with short spur routes, and the 500-series county routes in New Jersey have alternate, bypass, spur, and truck routes. A few highways have two special route designations. Some of these doubly designated special routes are: * Alternate Business US 66 in Springfield, Missouri * Business US 1A in downtown Bangor, Maine * Truck Business US 17 in Elizabeth City, North Carolina * Business US 77 Alternate in Yoakum, Texas *U.S. Route 202 Alternate Truck in Montgomery County, Pennsylvania (Many Pennsylvania highways use this "Alternate Truck" pattern) There is also an example of a route with three special route designations. U.S. Route 30 Alternate Truck Business provides an alternate truck bypass of U.S. Route 30 Business in Downingtown, Pennsylvania. 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「Special route」の詳細全文を読む スポンサード リンク
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