The mess at Eggner's Ferry Bridge
Saturday, January 28, 2012
- Last January, the Mississippi River Bridge at Cairo, Illinois, was closed to traffic after truck drivers ignored an emergency reduction in the weight limit (the bridge doesn't quite touch Kentucky, but is an important route for traffic between Kentucky and Missouri). The bridge is undergoing repairs but remains closed at this time.
- In September, the Shermin Minton Bridge at Louisville was unexpectedly closed after failing an inspection. It, too, is undergoing repairs but is still closed.
- Earlier this month, the Ledbetter Bridge (Clark Memorial Bridge) near Paducah had its weight limit reduced to only 3 tons. Law enforcement officers are now patrolling the bridge almost non-stop to prevent truck drivers from crossing. The alternative is to shut down the bridge to all traffic, just like at Cairo. (What I can't figure out is why Illinois and Kentucky won't install "headache bars" on the approaches to these bridges to prevent tall vehicles from crossing, which would effectively keep away overweight trucks at almost no cost or effort.)
- And now, of course, the Eggner's Ferry Bridge at Kentucky Lake was shut down in spectacular fashion on Jan. 26 as a large cargo ship slammed into one of the spans.
I visited Eggner's Ferry Bridge today, approaching from the western side at Kenlake State Resort Park. The park offers ample parking and several overlooks of the lake and bridge.
It's quite a spectacle:
The ship went under the wrong span (the second truss from the east). This span is not as high as the main channel span (second from the west). In the collision between the ship and the bridge, the ship easily won, crumpling the 322-feet Parker truss like a wad of paper.
With the ship anchored in place, the wreckage of the truss is now draped on the vessel's bow.
Bridge inspectors have tentatively declared that the western spans are stable, with commercial boat traffic allowed to resume passing under the main channel span. However, the eastern span (a smaller Pratt truss) has been labeled as "possibly unstable", with evidence suggesting that the pier has shifted -- or perhaps continues to shift. It also appears, at least through a telephoto lens, that cracks have formed in the concrete.
Pre-construction work is already underway on the bridge's replacement (a "basket-handle arch" design), but construction wasn't expected to finish until 2016 or 2017. I'm sure that schedule will be accelerated, but a major construction project can only proceed so quickly.
The Kentucky Transportation Cabinet hasn't ruled out trying to repair the existing structure, but it's going to be tough. First, the 322 ft. gap will need to be filled by a temporary span (perhaps some kind of Bailey truss). That's a lot of distance to cross. It's also likely that at least one pier and the smaller truss span on the east side will need to be replaced or shored up. If feasible, I'd say that repairing the bridge is worth the effort, but I suspect a certain number of local drivers will be terrified to cross the repaired bridge and would rather take a lengthy detour.
Unfortunately, some of the media coverage seems to be clinging to the usual narrative that this "aging" bridge suffered a "collapse." This wasn't a collapse at all: it was a collision caused by an errant ship. The bridge was built in 1932, but it was not considered structurally deficient according to an inspection in Aug. 2010. A large ship veering off course by almost 1,000 feet would be enough to tear apart even a brand new bridge. Indeed, a simple truss bridge, where each span is largely independent of the others, is one of the better designs to handle this kind of collision. Sadly, this incident will likely provide yet another excuse to replace historic bridges with mundane replacements that are shiny and new -- but never 100% accident-proof.