Photograph source：「Concrete Bridges in Hokkaido Vol２」（Association for Civil Engineering Technology of Hokkaido Concrete Research Committee）
| Structure name | Poroto Bridge |
|---|---|
| Structure type | ①PC single span hinged cantilever box girder bridge ②RC single span hollow slab bridge |
| Structural factors | （Up line） Length of bridge 200.0m Span length ①130.0m ②16.0m （Down line） Length of bridge 185.0m Span length ①116.0m ②16.0m |
| Client | East Nippon Expressway Company Limited. |
| Designer | Joint-venture group Sumitomo Mitsui Construction Co.,Ltd・Hishinaka Construction Co.,Ltd. |
| Contractor | Joint-venture group Sumitomo Mitsui Construction Co.,Ltd・Hishinaka Construction Co.,Ltd. |
| Location | Shiraoi town |
| Route name | Hakodate-Nayoro line HOKKAIDO EXPRESSWAY |
| Completion date | 1983 |
| Overview | This bridge was constructed in the Potoro natural forest preserve (a national forest), so a single-span hinged cantilever bridge form was adopted to reduce environmental impact but not requiring the use of supporting structures. In addition, the Dywidag method was also used to protect against the surrounding environment. As the substructure would receive all of the loading due to the cantilever construction method, replacement concrete was poured to improve the stability of the supporting soil. In addition, concrete was also poured in the box girders to serve as a counterweight due to moment from the superstructure. During the winter period, a shed was constructed around the entire construction vehicle, and curing was managed using an air-heating machine. This bridge received the Technology Award of the Japan Society of Civil Engineers Hokkaido Branch in 1983. |
