Standard diamond - Kikakudaiya

...Train timetables are created in the following order: (1) Entering express passenger trains, high-speed and direct freight trains, etc. into the first hour timetable and considering arrival and departure times, connections, and vehicle operations at major stations, (2) Entering and considering regular passenger trains and general freight trains, and (3) Creating a second hour timetable using a similar method. Express trains, container trains, and fresh fish trains, which have many restrictions on arrival and departure times, are often difficult to adjust within the limited track capacity, and in densely packed sections around large cities, in order to maximize track capacity, parallel timetables are used in which all trains run at the same speed, and standard timetables are used in which high-speed trains run at low speeds and the speed difference with low-speed trains is reduced. [Masao Yamazaki]...

*Some of the terminology used to refer to "standard diamonds" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…列車ダイヤの作成は，(1)1時間目ダイヤへの特急旅客列車，高速･直行貨物列車などの記入および主要駅の発着時間帯，接続，車両運用などの検討，(2)普通旅客列車，一般貨物列車の記入および検討，(3)同様な手法による2分目ダイヤの作成の順で行われる。発着時刻に制約の多い特急列車，コンテナー列車，鮮魚列車などについては限られた線路容量のなかで調整に困難を伴うことも多く，また，大都市周辺の列車稠密区間では線路容量を極力増やすため，全列車の速度を同一にした平行ダイヤ，高速列車の速度を低くし，低速列車との速度差を小さくする規格ダイヤを採用している。【山崎 正夫】。…

※「規格ダイヤ」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報