Through this channel improvement work, the lower reaches of the Hira-kawa River that flowed into Sumida-gawa River after passing through Hitotsu-bashi Bridge, Kanda-bashi Bridge, and Nihon-bashi Bridge, was cut-off from the Kanda-gawa River (former Hira-kawa River) and became the Edo Castle moat.
この工事によって平川下流であった一ツ橋、神田橋、日本橋を経て隅田川に至る川筋は神田川（平川）から切り離され、江戸城の堀となった。