Iroha Bridge - Irohabashi

Japanese: いろは橋 - いろはばし

...The city was established around Ichibazaka on the street in front of the north exit of Shiki Station on the Tobu Tojo Line (opened in 1914). Originally, the Nobidome Irrigation Canal (Izudonobori) flowed through the middle of this street, and a suspended canal called Irohadoi carried water across the Shingashi River to the rice fields in the Muneoka area, but now it is an underground canal, and only the name Irohabashi remains on the prefectural road crossing the Shingashi River. As it is 30 km from the center of Tokyo, the number of houses has increased dramatically since the 1960s, and a new town was built in the lowlands along the Yanase River, a tributary of the Shingashi River, and Yanasegawa Station was opened in 1979. ...

From [Nobidome Irrigation Canal]

...It is said that the civil engineering work to open up the flat land was inexperienced, making it difficult to get water to flow, and that the work was carried out at night, measuring the area by lanterns and incense. The Iroha-hi conduit remains in the place name as the Iroha-bashi bridge. The water that was once used for daily life became polluted after the 1960s due to urbanization of the basin, but a movement to restore the clear water has been underway in the relevant areas, and some of the water is now flowing.

*Some of the terminology that refers to "Iroha Bridge" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…東武東上線志木駅(1914開業)北口駅前通りの市場坂あたりが市の立った所である。もとはこの通りの真ん中に野火止用水(伊豆殿堀)を流し，伊呂波樋（いろはどい）と呼ばれる懸樋で新河岸川をこえて宗岡地区の水田に引水していたが，今は暗渠となり，新河岸川を渡る県道にいろは橋の名だけ残る。東京都心から30kmにあるので，1960年代以降住宅が激増し，新河岸川の支流柳瀬川沿いの低地にもニュータウンが建設され，79年には柳瀬川駅も開設された。…