NEXCO West Japan: At Least Two Years Until Full Reopening of Minami-Kyushu Expressway

NEXCO West Japan has indicated that it will take at least around two years before all road closures on the Minami-Kyushu Expressway, which was damaged in the Kumamoto earthquakes, can be lifted.

Following an inspection of the damaged Myoken No. 1 Bridge, it was determined that damage to the bridge girders in both directions was localized. Although yielding was found in some components, the girders can be reused through partial replacement and reinforcement. Yielding was also found in some bridge-pier components, but they are expected to be reusable after reinforcement. No damage was found to the pile foundations.

The restoration policy was confirmed to prioritize the earliest possible lifting of road closures. Given the difficulty of predicting fault displacement, bridges located on fault zones will be designed to avoid, as far as possible, catastrophic damage such as bridge collapse. The structures will also be designed to allow prompt emergency restoration following damage, in anticipation of a similar earthquake occurring again during their service life.

The review committee discussed technical issues concerning four restoration plan options. These included plans to reuse the existing girders as much as possible or to replace the girders, both of which would allow road closures to be lifted approximately three years after design work begins; and plans using either continuous girders or simple girders for the superstructure at the fault-crossing section, both of which would allow road closures to be lifted in approximately two years. Going forward, the committee will specifically examine the technical issues of the two plans that best align with the priority of lifting road closures as early as possible, and will decide on a restoration plan at its next meeting.

Meanwhile, general vehicles have been permitted to use the Kyushu Expressway since August 14, with two-way traffic operating on a single carriageway in some sections. Restoration work on Kawata Bridge is expected to restore four lanes along the entire section by around the end of 2027. General vehicles have also been permitted to travel between Hinagu Interchange (IC) and Tanoura IC on the Minami-Kyushu Expressway since August 18.