The Trans-Tokyo Bay Highway Project aims to build a highway under Tokyo Bay to improve transportation. The project faces challenges like earthquakes and soft ground. To address these issues, shield tunnelling and diaphragm walling techniques are being used. New construction methods, like man-made embankment fill and ground improvement with cement-treated sand, are being developed to ensure safety during tunnel excavation. The project is still ongoing, with researchers continuously testing and improving construction techniques to make the highway a reality.