Various Levels of Protection for Bridge Piers Written by dmorista

 Various Levels of Protection for Bridge Piers Written by dmorista

The recent collapse of the Francis Scott Key Bridge, in Baltimore Harbor, pointed out the shocking lack of basic efforts to protect expensive and difficult to replace public works such as that bridge. The original cost of building the Francis Scott Key Bridge was $60 Million (that translates to $360 Million in 2024 dollars). It also took 5 years to build the original bridge, that was still rated as “Fair” by bridge inspectors after 47 years of service. The main bridge piers had been recently downgraded from about a 78 rating to a 64.5 rating, but they were still fully functional. Building the new Bridge, to replace the original Francis Scott Key Bridge, will certainly cost at least $2 Billion to $3 Billion and perhaps more; it will also take a minimum of 3 years to complete, on the most optimistic conceivable schedule. In comparison a program for a few million dollars, of constructing Fender and Dolphins, looks pretty cheap in retrospect.

The Port of Baltimore undertook a major expansion a few years ago, but there was no attempt to upgrade the protection for the vulnerable main piers, or the other piers, of the Francis Scott Key Bridge. There have been various reports, including one in 2022, about improving protection systems to allow bridges to survive ship and barge collisions. I have heard and read several opinions that there was basically no way to improve the protection of the Bridge's Piers; that included a few minute long comment on the bridge collapse, on NPR's venerable show “Science Friday”. In which the commenter lamented that the ship was just too big and nothing could be done. That is complete bunk, there were relatively cheap and easy methods to improve the survivability of the Francis Scott Key Bridge.

In this essay I am presenting several graphics that demonstrate varying levels of commitment to protecting the Bridges in question from catastrophic damage and collapse. First the Francis Scott Key Bridge actually had some tiny inadequate “Dolphins” that were incapable of protecting the bridge from a forseeable collision like the one that occurred on March 26^th. Figures 1 & 2 show the location of these inadequate “Dolphins”, I and many others were not even aware of their existence.

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The Bridges that cross the Delaware River in the area in and around Philadelphia have been provided with serious, if less than total protection. The “Dolphins” installed to retrofit the Betsy Ross Bridge are the example of the level of protection provided to that set of bridges. So far the “Dolphins” were yet to be tested as far as I am aware. Figure 3 is an example of that level of protection.

The Sunshine Skyway Bridge, in Tampa Florida is an example of a serious effort to protect the new bridge (built to replace one of the original two spans that was struck by a freighter and collapsed.) Even the original pair of Sunshine Skyway Bridges were far better protected than the Francis Scott Key Bridge. They had substantial “Bumpers” protecting the two main piers, but the ship that hit the old Sunshine Skyway Bridge was driven off course during a heavy rain squall and thunderstorm and hit the next pier out, and that did not have any protection. The replacement bridge has significant and serious Dolphins to protect the various Bridge Piers and Towers. Figure 4 shows this situation.

However we need to go to Asia to find an example of maximum effort to protect a Bridge from Ship and Barge collision catastrophes. The Incheon Bridge in South Korea has a truly serious set of “Dolphins” protecting its important structural elements. While I found this fine photo of the bridge at Mageba I want to acknowledge that I was made aware of the existence of these serious “Dolphin” system by “Casey Jones – Professional Engineer” at “Baltimore Bridge Collapse”, March 26, at < https://www.youtube.com/watch?v=CHYUlukEdOE >.

There is no perfect solution to the problem of protecting Bridges from ship and barge colllisions. Ships have gotten much larger than was the case when either the original Sunshine Skyway Bridges and/or the Francis Scott Key Bridge were built. But it is clear that a more serious attempt is needed than what was the case in Baltimore. Passive measures like Dolphins are the most important, but also there are questions of the seaworthiness of ships to leave the docks. This question has come up in reference to the MV Dali that according to some reports had significant electrical problems and system failures while at the dock. And for the really large ships, from the size of MV Dali and up, tugs should accompany the ships until they get out into the open sea.

The South Koreans are clearly willing to commit the resources to protect their recently built bridges. The example of the Incheon Bridge and its impressive “Dolphin” system is found in Figure 5.