Mezue ahịrịokwu na-esonụ: E. H. Harriman kwadoro Dumbarton Rail Bridge (nke a maara mgbe ahụ dị ka Dumbarton Point Bridge ma ọ bụ, nanị, Dumbarton Bridge; otu n'ime ihe owuwu ndị bụ́ isi nke ụzọ ụgbọ okporo ígwè Dumbarton Cut-off). Tupu e wuchaa Dumbarton Cut-off, a na-ebupụ ibu ụgbọ okporo ígwè na Oakland ma na-ebufe ya na San Francisco. Ọrụ mbido bidoro na 1904 site na nkatọ nke ala na Dumbarton Point, na ntinye nke Central California Railway Company, nke ọtụtụ ndị ọrụ South Pacific mepụtara maka naanị ebumnuche nke iwu ụzọ ụgbọ okporo ígwè site na Newark ruo San Mateo. E nwere ụfọdụ mmegide megide àkwà mmiri ahụ site n'aka ndị otu azụmahịa dị n'ógbè ahụ, na United States Army Corps of Engineers mere nzukọ ọha na eze n'August 1906 na-akpọ oku maka nzaghachi ọha na eze na atụmatụ maka àkwà mmiri ahụ. Henry Rengstorff rụrụ ụka na àkwà mmiri ahụ ga-egbochi okporo ụzọ mmiri, nke dị mkpa dị ka ụzọ ọzọ n'ọnọdụ nke ụgbọ okporo ígwè ma ọ bụ ọdachi ndị na-emere onwe ha, dị ka
ala ọma jijiji mere n'oge na-adịbeghị anya.