(IMAGE) Tohoku University Caption This is a photograph of typical extradosed bridge construction, in which one of the most important parts is the sustaining PC bundled steel cables sealed with invisible polyethylene. Credit Yutaka Oyama Usage Restrictions Credit: Yutaka Oyama License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.