Irawan FAJE, Wahyuni A. Cost And Productivity Analysis Of Installing 40 X 60 X 120 U-Ditches Using Heavy Equipment Compared To Manual Methods In Sumur Welut, Lakarsantri District, Surabaya: Analisis Biaya Dan Produktivitas Pemasangan U-Ditch 40 X 60 X 120 Menggunakan Alat Berat Dibandingkan Metode Manual Di Sumur Welut, Kec. Lakarsantri, Surabaya. ijins [Internet]. 2026 Oct. 13 [cited 2026 Oct. 15];27(2):10.21070/ijins.v27i2.2438. Available from: https://ijins.umsida.ac.id/index.php/ijins/article/view/2438