Marshalling yard

A type of station, a place established for the composition of trains or the switching of cars. Also called a yard. There are two types: passenger car marshalling yards and freight car marshalling yards.

A passenger train marshalling yard is a place where passenger cars of arriving passenger trains are cleaned, washed, inspected, reassembled, stored, and prepared for departing trains. However, as the number of electric trains and diesel cars increased and electric and diesel locomotives began to replace steam locomotives, comprehensive vehicle depots were established near terminal and starting stations to inspect, repair, clean, and maintain not only passenger cars but also these cars. Therefore, the name marshalling yard was mainly used to refer to freight train marshalling yards after that. Furthermore, freight marshalling yards require a considerable amount of land, and due to the problem of land costs caused by rising land prices, there have been ongoing developments toward abolition. Then, JNR completely abolished freight car marshalling yards with the timetable revision implemented in November 1986 (Showa 61). In April 1987, JNR was divided and privatized, and JNR's freight division was taken over by Japan Freight Railway Company (JR Freight). JR Freight focuses on "large-scale standardized transportation," which allows it to utilize the characteristics of rail freight in the highly competitive logistics market, and is in charge of direct transport by container and specialized transport for specific goods. Here, we will explain the former freight handling yard.

A freight car marshalling yard is a place where all or part of arriving freight trains are disassembled and sorted, organized by destination and station, and reassembled into freight trains.They are established in locations where the flow of goods is concentrated, such as in the outskirts of large cities and industrial cities, at the junctions of major trunk lines, and at relay points between sea and land connections.

The role of a freight car marshalling yard is to sort and group the arriving freight cars according to the prescribed classification, to assemble the grouped freight cars according to the composition method prescribed for each train, to prepare the train, to dispatch empty cars suitable for the cargo to be loaded to freight stations, to temporarily store empty cars that are no longer needed or arriving cars that cannot be loaded or unloaded at freight stations, and to adjust the train towing capacity. Since many freight trains start and end at marshalling yards, locomotives are changed, crew members are replaced, and freight cars are inspected and repaired. For this reason, large marshalling yards are equipped with locomotive depots, freight car inspection and repair depots, and crew depots.

Depending on the method of sorting, freight car marshalling yards are broadly divided into planar yards, where freight cars are sorted by pushing them off the ground with a shunting locomotive, and hump yards, where freight cars are sorted by rolling over a hump. Planar yards have a maximum daily handling capacity of 2,000 to 2,500 cars, while hump yards (one-hump yards) have a maximum daily handling capacity of 2,000 to 3,000 cars on a single-track push-up line and 3,000 to 4,000 cars on a double-track push-up line. Planar yards cut the couplers of the train of freight cars to be sorted, and then push them onto the siding by a locomotive. Then, by accelerating and braking, the freight cars are pushed off the tracks to the desired sorting tracks, and this process is repeated as many times as the freight cars are disassembled. This method takes a long time to disassemble, but it is inexpensive to build, so planar yards are often found in small yards. In the case of a hump yard, a small hill (2-5 meters high) called a hump is set between the push-up line and the sorting line, and a shunting locomotive pushes a train of freight cars installed on the push-up line up to the hump, cuts the couplers of the freight cars at the top of the hump, and the freight cars roll naturally onto the sorting line. The gradient of the hump is 40-70‰ (per mille, thousandths) at its steepest point, and gradually becomes gentler. This method is efficient because it requires a short time for sorting work, so the hump system is often used in large-scale marshalling yards. There are several methods for stopping freight cars rolling over the hump on the sorting line: a method in which a yard worker rides on the freight car from the hump and applies the handbrake to stop it, a method in which a car retarder is used to remotely slow down the freight car, and a yard worker jumps on a freight car approaching at a low speed and applies the handbrake to stop it, and a method in which a hem shoe is used to slow down and stop the car.

Much of the work in freight car marshalling yards is manual, resulting in low productivity, and many tasks are highly dangerous, so automation has been developed to reduce the number of workers in the yards and improve work efficiency and safety. This can be broadly divided into the automation of freight car speed control and the modernization of information processing. The former includes the target shooting system, the dowty (hydraulic acceleration/deceleration) system, and the linear motor system, which eliminate the need for braking personnel. The latter uses computers to create work plans, control routes within the yards, and compile statistics.

[Hiroshi Tsuchida]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

停車場の一種で、列車の組成、または車両の入れ換えを行うために設けられた場所。ヤードyardともいう。客車操車場、貨車操車場の2種類がある。

　客車操車場は、運転を終えて到着した旅客列車の客車を清掃、洗浄、検修、組替え、留置し、また出発する列車の仕立てを行う場所である。しかし、電車やディーゼル車が増え、蒸気機関車のかわりに電気機関車、ディーゼル機関車が使われるようになると、客車だけでなくこれらの車両を検査、修理、清掃、整備する総合的な車両基地が終着・始発駅の近くに設けられるようになった。したがって、その後は、操車場の名称はおもに貨車操車場について使われていた。さらに貨物操車場についても、かなりの規模の用地を必要とするため、土地価格の高騰による用地コストの問題から廃止の方向で整備が続けられてきた。そして国鉄では、1986年（昭和61）11月に実施したダイヤ改正で貨車繰車場を全廃した。87年4月に国鉄は分割・民営化され、国鉄の貨物部門は日本貨物鉄道（JR貨物）に引き継がれた。JR貨物では、競争の激しい物流市場のなかで鉄道貨物の特性を発揮できる「大量定型輸送」を中心とし、コンテナによる直行輸送、物資別専用輸送を担当している。ここでは、かつての貨物操作場について解説する。

　貨車操車場は、到着した貨物列車の全部または一部を分解のうえ仕分けし、行先別・駅順に整理し、組成替えして貨物列車を仕立てる作業を行う場所で、物資の流動の集中する大都市、産業都市の周辺、主要幹線の分岐点、水陸連絡の中継点などに設置する。

　貨車操車場の役目は、集まってくる貨車を定められた仕分け区分に従って仕分けし、グループ化すること、グループ化した貨車を列車ごとに定められた組成方法に従って組成し、列車を仕立てることのほか、貨物駅に、積込み貨物に適合した形式の空車を操配すること、一時不要となった空車や貨物駅で積卸し作業の余裕のない到着車を仮留置しておくこと、列車牽引(けんいん)定数を調整することなどである。なお、操車場で始終着となる貨物列車が多いので、機関車の付け替えや乗務員の交替、貨車の検修作業が行われる。そのため、大規模な操車場には、機関車基地、貨車検修基地、乗務員基地が併設される。

　貨車操車場は、貨車の仕分けの方法により、平面で入換え機関車による突き放し作業によって仕分けを行う平面操車場と、ハンプからの自然転走によって仕分けを行うハンプ操車場（ハンプヤード）とに大別される。1日取扱い能力は、平面操車場の場合、最大2000～2500両、ハンプ操車場（ハンプ一山）の場合、押上線一線で2000～3000両、押上線二線で3000～4000両である。平面操車場の場合は、仕分けしようとする貨車列の連結器を切り、機関車で推進運転により引上線に据え付ける。そして、加速したのち制動を行うことにより、貨車を目的の仕分け線へ突き放す作業を、貨車の分解回数だけ繰り返す。この方式では、分解に長時間を要するが、建設費が安いので、小規模な操車場には平面操車場が多い。ハンプ操車場の場合は、押上線と仕分け線との間にハンプという小山（高さ2～5メートル）を設け、押上線に据え付けた貨車列を入換え機関車によってハンプに押し上げ、貨車の連結器をハンプの頂上で切って、貨車を仕分け線へ自然転走させる。ハンプの勾配(こうばい)は、最急部分で40～70‰（パーミル、千分率）とし、順次緩やかなものに変化させる。この方式では、仕分け作業の所要時分が短く能率的なので、大規模な操車場にはハンプ式が多い。ハンプから転走してくる貨車を仕分け線内で停車させる方法には、構内作業員がハンプから貨車に添乗しサイドブレーキを扱って停車させる方法、カーリターダーによって遠隔操作で貨車を減速させ、低い速度で進入してくる貨車に構内作業員が飛び乗ってサイドブレーキにより停車させる方法、およびヘムシューによって減速停車させる方法がある。

　貨車操車場における作業の多くが人手に頼っていて生産性が低いうえ、危険度の高い作業も多いので、構内作業要員の縮減と作業能率、安全度の向上のため作業の自動化が開発されてきた。それは、貨車速度制御の自動化と情報処理の近代化とに大別される。前者には、ターゲットシューティング方式、ダウティ（油圧加減速）方式、リニアモーター方式などがあり、制動要員が不要となる。後者は、コンピュータを利用して、作業計画の作成、構内の進路制御、統計類の作成などを行うものである。

［土田　廣］

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