{"id":6927,"date":"2016-10-24T08:49:08","date_gmt":"2016-10-24T12:49:08","guid":{"rendered":"https:\/\/wawa-news.com\/?p=6927"},"modified":"2018-04-17T15:51:52","modified_gmt":"2018-04-17T19:51:52","slug":"the-nipigon-river-bridge-failure-who-accepts-responsibility-for-poor-design-installation-who-pays","status":"publish","type":"post","link":"https:\/\/wawa-news.com\/index.php\/2016\/10\/24\/the-nipigon-river-bridge-failure-who-accepts-responsibility-for-poor-design-installation-who-pays\/","title":{"rendered":"The Nipigon River Bridge failure\u2026 Who accepts responsibility for poor design, installation & who pays?"},"content":{"rendered":"

Oct 24, 2016 @ 08:49<\/b><\/p>\n

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photo credit to Natalie Hardy\/Facebook (Northern Ontario Traffic Alerts – Alertes Routiers)<\/p><\/div>\n

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The Nipigon River Bridge failed dramatically \u2013 the western side rose 60 centimeters midafternoon on January 10, 2016, and was closed immediately by Nipigon Ontario Provincial Police. \u00a0An estimated 200 metric tons (200 long tons; 220 short tons) of concrete\u00a0jersey barriers\u00a0<\/a>were placed\u00a0on the deck to hold it down, and the bridge reopened to one-lane, escorted traffic the next day. 24-hour monitoring of the bridge joints and bearings continued while repairs were underway.\u00a0The bridge had failed after only 42 days in operation. Thankfully, there were no injuries.<\/p>\n\n\n\n\n
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North Girder \u2013 \u201cThis picture shows the existing bearing system. This is not the new system that is being installed. (MTO)\u201d \u2013 this is now titled the \u2018north-west\u2019 bearing by Associated Engineering.<\/p><\/div>\n

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On February 25th, 42 days later, the bridge was reopened to full traffic \u2013 a new temporary support (above),\u00a0a new hold-down system had been installed and the jersey barriers removed, without any explanation as to what exactly went wrong. This new \u201ctemporary repair\u201d, \u201cPrimary temporary repair\u201d, \u201cTemporary repair system\u201d, \u201cHold-down support system\u201d has it has been termed in various reports, was reviewed by Associated Engineering, and no concerns were found. Photo to the right shows the existing bearing system as photographed in February.<\/p>\n

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Figure 1-3: Bearing Nomenclature (from Ministry of Transportation \u2013 Nipigon River Bridge Independent Technical Review by Associated Engineering).<\/p><\/div>\n

In the meantime, attention was being focussed on the bolts that failed. Bolts were sent to the National Research Council of Canada in Ottawa and Surface Science Western at Western University for testing.\u00a0When the results of testing were released on July 4th, 2016 some things became clear. However, the MTO updates on the Nipigon Bridge said, \u201cThe bolt study provided us with only a partial answer about the bridge, and as such we think it\u2019s premature to discuss it on its own at this time.\u201d<\/em><\/p>\n

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Figure 1-2: Fractured bolts (ASTM A490 bolt \u2013 connecting shoe plate to girder flange) and deformed shoe plate at north-west bearing. Note four lines of failed flange connection bolts. (Ministry of Transportation \u2013 Nipigon River Bridge Independent Technical Review, by Associated Engineering, September 2016)<\/p><\/div>\n

The conclusions from the testing of bolts were that the bolts met the requirements and were not the reason for the failure. Examination of the bolt failure surfaces revealed that they had marks consistent with low-cycle high-stress bolt failure. They also noted that corrosion was observed, meaning that the failure was progressive and began prior to January 10, 2016.<\/p>\n

Analysis of the bearing revealed that the failure was caused by three factors, which on their own was significant and may have led to a failure but together made \u201cfailure inevitable\u201d<\/em>.<\/p>\n