IStructE believes that ongoing risk assessment of structures is critical. Investigators will review the pier design and changes to vessel impact protection devices to determine potential shortfalls in risk management.
Bridge expert Ian Firth, independent consultant, IStructE’s past-President and a Fellow comments as follows:
“It is almost impossible to design a bridge pier to withstand this kind of impact. Therefore, we tend to design impact protection measures to prevent it from happening instead."
“Dolphins or other vessel impact protection devices in the water are commonplace since the Sunshine Skyway collapse in 1980. But this bridge was built in the 1970’s, so the design would not have incorporated these devices at that time. The fact that a vessel can veer off course and hit the pier is the reason to design vessel impact protection systems so that a large vessel cannot hit the critical bridge support."
“The footage shows there are small dolphins, (the small round objects visible in the film), each side of the bridge piers - these have not prevented the vessel hitting the pier.
“A new bridge design would probably be a cable stayed bridge with a much larger span, moving the supports well away from the navigation channel and into shallower water.”
IStructE also considers that a full investigation will have to address many aspects of why this happened, asking questions such as:
- There are navigational rules for ships, why was this vessel out of its channel?
- Bridge piers are normally protected from impact, so what exactly was the pier design?
- Are the codes and regulations sufficient for today’s increasingly larger cargo ships?
- Are further measures required to ensure this does not happen again?
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