This is because railways and roads were constructed integrally under the control of the former Ministry of Construction, and the Higashi-Osaka Line was the first in Japan to use a structure integrating an elevated bridge for a highway and that for a railway, attracting attention at that time as a system providing an effective means of usage when a wide road isn't available.
これは当時の旧建設省管轄下で道路と一体的に工事を行うためであり、高速道路の高架橋と鉄道の高架橋による一体的な構造物はこの東大阪線が日本初で、道路幅員が大きく取れない場合の有効手段として当時大きく注目されていた。