Building so-called social infrastructure has huge potential abroad, prompting Japanese companies to form broad corporate alliances, often with government support, to win contracts for overseas projects.

Heavy electric equipment makers Hitachi Ltd., Toshiba Corp. and Mitsubishi Heavy Industries Ltd. aim to make inroads in building social infrastructure overseas because there is little perceived need for new projects at home, whereas emerging economies appear to have huge potential, experts said.

Demand for railways, energy plants, information technology, water supply systems and other infrastructure is surging. The Organization for Economic Cooperation and Development estimates the market will amount to $40 trillion by 2030.