Abukuma Ohashi Bridge

摘要

The four-lane project between the Yamamoto interchange (IC) on the Joban expressway and the Iwanuma interchange on the Sendai Tobu expressway, which is a 14km-length section was permitted in 2016 as part of the reconstruction projects of the Great East Japan Earthquake, and the project was proceeded with a limited construction period aiming at the completion within the "Reconstruction and Revitalization Period" of the Earthquake (within the fiscal year of 2020). The four-lane project in this section is expected to alleviate the decrease in travel speed due to traffic congestion, reduce the number of accidents that jump out to oncoming lanes, improve the ease of maintenance and functions, and strengthen the cooperation with parallel national highways.The Abukuma Ohashi Bridge is a five-span continuous steel box girder bridge with a steel plate deck having a bridge length of 534.3m and a maximum span length of 110m located between the Watari IC and the Iwanuma IC, of which the substructures are a pneumatic caisson foundation & column type piers and cast-in-place pile & inverted T-type abutments. As the bridge construction is close to the Phase Ⅰ bridge in-service with about 3m distance, various safety measures were carried out.Since it was also necessary to complete the bridge in three consecutive dry seasons (i.e. three years), a shortening of the construction period was attempted by making the temporary bridges for construction to be a structure capable of year-round installation. The pier caisson method was applied, and large-sized forms were adopted to cast the concrete to shorten the process, and four piers were constructed simultaneously day and night. The superstructure was elected using three crawler cranes, and efficiency improvement and optimization of the work procedures were attempted, and the bridge could be successfully completed in May 2020.