I-40 Arkansas River Bridge

We have had so many hits from people looking for info about this bridge, that we have finally put up this page about it.

The bridge you see here is a continuous steel deck girder with simple span deck girders for approaches. The repaired portion of the bridge consists of a side span of the continuous main portion, and simple, concrete stringer spans to replace the approach spans that had been knocked down.

The first picture below is a deck view looking west. The deck and guard details were matched in the repaired sections.

The photo above clearly shows the main span and its cantilever side spans, as well as the west approach spans. As was stated at the top of this page, this is a deck girder bridge, not a stringer bridge. The difference is notable when comparing the original bridge and the repaired section. The bridge is four lanes wide, but is constructed like two 2-lane bridges sharing common piers.

Below, a view of the rebuilt spans showing the piers used. While the old sections use 2-leg piers connected by a tall shear wall, the new  piers each use three legs with a "grade beam" above the water line. This is done because the remains of the old piers are still below the water line.

Above, a close-up of the main span. Note please that the channel is between the main span piers, and not between a main span pier and an approach pier. The approach span piers in the background are identical to the one which was knocked down. While these piers do fine at holding the tremendous weight of the bridge and the current of the river, they would have to be well over 30 feet in diameter to resist the enormous weight and momentum of a barge and tug boat! Many are familiar with the lengthy distances required to stop a moving train, but a single barge that hit this pier is equal to 32 loaded rail cars, and although it was only going 5 knots, boats do not stop on a dime either, so it might as well be the equivalent of 32 rail cars moving at 60 miles an hour.

Note that the rebuilt portion of the bridge was built to "modern standards", but would still collapse if hit by this kind of force.

If you are trying to fault ODOT for this tragedy by arguing that the bridge was dilapidated, you are wasting time.

Below, do not confuse cantilever with continuous. This bridge is a continuous span bridge, meaning that even the outer ends of the side spans require support. We have labeled a few parts in this photo to help you understand bridge construction. Large, deep girders like these require stiffening in the web, that is, the material between the flanges, which are synonymous with the chords in a truss bridge. The web in a beam bridge performs basically the same function as the web members in a truss, but with much more material. At (A) is a stiffener, which aids in making the web more ridged. These are placed at regular intervals, dividing the girder up into panels (B). Note that at (C) an additional horizontal stiffener has been added parallel to the lower flange. At (D) is another one of these horizontal stiffeners. Note that panel (B) should have a stiffener. However, as you can tell by the paint, panel B is the part of the side span which collapsed, and from the right stiffener of panel B to the left is all new. However, a different type of steel was reused in the reconstruction, thus the stiffeners were not needed.

Please also note the barrier dolphins at (F). These were placed on either side of the channel and to guard the piers adjacent to the channel. However, in the accident, the barge was soo far off course, that these were useless. Although these dolphins seem big, they too would probably have been displaced if hit.

The shear wall (E), in conjunction with the cap beam at the top, connects the piers into a single unit. These are identical to what was knocked down my the barge.