The bridge over the Buffalo River at Pruitt (yes, "my" Pruitt), came down this week

Old Pruitt Bridge over the Buffalo National River after 

the deck (pavement) was removed, 

before explosives were used to take down the bridge.  

A bridge built in 1931, the last Pennsylvania through-truss bridge in Arkansas, came down on Wednesday--with the help of explosives.  That bridge was part of Scenic Highway 7 and crossed the Buffalo National River at Pruitt.  Yes, that's the same Pruitt as my paternal family.  Pruitt used to have its own post office (up til the 1970s) but more recently hosted a Ranger Station for the National Park Service.   It is in Newton County, just a few miles south of the Boone County line and in a rural area.  Just west of there now is Pruitt Landing, 

The best video I've seen of the implosion of the bridge is compliments of Crouse Construction, which built the replacement bridge that opened on May 14.  A video from a different angle is here, compliments of the Harrison Police Department.  

Some recent stories about the bridge and its history include one from the Arkansas Democrat-Gazette here.  It includes this information about the bridge's design:

Regarding the design of the old Pruitt bridge, Dave Parker, a spokesman for the Arkansas Department of Transportation, said in an email: "The Buffalo River (Pruitt) bridge truss design is a variant of a Pennsylvania through-truss with Warren pony trusses on either side. The through-truss connection to the pony trusses displays a unique design; it has not been identified to date in any other bridges. The Buffalo River (Pruitt) bridge is also the last variation of the Pennsylvania though truss design in service on Arkansas roadways."

This is from a Newton County Times story about the state of the bridge once the deck was removed:

You’ve seen it as a landmark. Your parents and possibly even grandparents have seen it that way, too. After nine decades, the Pruitt bridge will come down, officials say.

Crouse Construction of Harrison was contracted to build a new bridge over the Buffalo National River. It’s now open and the old bridge will be imploded today, Wednesday, if the weather cooperates.

And by looking at the old bridge with all the decking and pavement removed, it’s probably past time for that to happen.

Crystal Crouse with Crouse Construction is overseeing the entire project.

“The deck of the bridge was really keeping the majority of the structure in place,” Crouse said. “Pavement was really what was keeping it together.”

She explained that some of the X-member support braces were so corroded they began to fall when the pavement was removed.

Bridge foreman Eddie Mitchell said two concrete slabs started on either end of the old bridge and met on the center pier. When the two-inch layer of asphalt atop the concrete was taken up, they found that the concrete slabs were barely touching the beam on the pier under it, which Crouse said was the main strength for the bridge.

Some of the beams on which the decking rested showed daylight through corroded holes. Crouse said much of the steel structure is in such bad shape that it can’t even be salvaged for scrap.

Mitchell said some of the massive beams for the new bridge were hauled in from the south and over the bridge. Had they known the condition of the bridge at that time, they wouldn’t have crossed the bridge.

Crouse and Mitchell and their crew are largely from Boone and Newton counties. Crouse said her grandfather lived in Jasper and used the bridge daily. They recognize the gravity of a landmark that many people wanted to save.

“I know it’s an old, historic work of art, but it’s needing to come down,” Mitchell said. “What we were driving on was rotten.”

And here's a story about the bridge's history, also in the Newton County Times, quoting from the Historic American Engineering Record.   As you'll see below, the cost of the bridge was just $55K, and the winning bidder was based in Topeka, Kansas.   

(Pruitt Bridge)
HAER No. AR-23

In February 1931 Arkansas State Highway Department began to consider replacing the bridge over the Buffalo River on the scenic Highway 7 near Jasper, county seat of Newton County. Officials were said to be "not seriously alarmed by the condition of this bridge," indeed, an anonymous representative of the Bridge Department was recorded as saying that the old bridge "was almost as good today as when it was built." However, while the old bridge was not in a condition that required immediate replacement, its older design could withstand only limited loading. In a study of the older bridge by the Highway Department, the bridge engineers suggested that "a three ton load limit sign should be placed on the old Buffalo River bridge."

DESIGN AND CONTRACT

The design of the new bridge for the Buffalo River was not yet underway by April 8, 1931.
The State Highway engineer W.M. Mitchell, reported in a letter of that date that the bridge designers had not "been able to get the plans started due to other work that was ordered ahead of this."

On May 6, Mitchell requested the bridge engineers of the State Highway Department to commence and complete the plans "as early as possible." He specifically requested the urgent attention of the bridge engineers to this project as "considerable pressure is being brought to bear to get this bridge in the next letting. " It cannot be ascertained precisely where that "pressure" was coming from, but the dire need for bridge projects to aid employment in the years of the Depression would suggest that pressure originated at county level.

The plans were commenced on May 11, 1931, and, remarkably, completed the next day.
The contract was advertised on May 13, with an estimated cost of $65,461.43. The contractor, Fred Luttjohann, of Topeka, Kansas, received the contract for the lowest bid of $55,226.09. Work began on the bridge on July 18, 1931, with a contracted building period of 210 days.

Fred Luttjohann was, as with many of the bridge contractors of the 1920s and 1930s, a largely unknown figure. He was involved with a number of Arkansan bridges of the period, but as a contractor he was primarily engaged in subcontracting work, consequently leaving his work as regards the contracts largely supervisory and anonymous. His work, however, was regularly advertised in the State Highway Department magazine of the period. Advertisements there declare that his bridges are "built for the ages."

ENGINEERING DESCRIPTION

The Pruitt Bridge is a steel truss of total length 375 feet, comprised of a center span of 160 feet, two end spans of 80 feet each, and a 55-foot girder approach span on the south end. The Warren end spans and the Pennsylvania main span all have eight panels, where a panel is defined by the space spanned by a main diagonal. The horizontal, vertical, and diagonal sub-struts of the main span radiate from the main diagonal at mid-panel width. The end spans have verticals at every other panel point, meeting the top chord where the diagonals are riveted to it.

The inclined top chord of the end trusses slopes five degrees upward to the polygonal top chord of the main span. The top chord for the entire bridge consists of two 10-inch-deep channels, increasing in weight toward the center of the span, joined by a continuous top plate and lacing bars. The chord is riveted along its length except for a pin connection between the main and secondary span at U7 (see Highway Drawing No. 3223). During construction this joint was riveted to support the center span, which was cantilevered from the end spans. Once the center span was complete, the bridge carried forces as three trusses, and all weight was transferred to the piers and not from one truss to another. So member U7-U8 did not carry any axial load.

The bottom chord, two 12-inch-deep channels with lacing and batten plates, is also pin connected at L8 to a fixed hinge on a concrete pier. The similarly positioned panel point on the other end of the bridge is pinned to an expansion rocker, as are the extreme ends of the end spans.

All verticals, sub-struts, and diagonals are riveted to the chords. Throughout the bridge the web members are 10-inch-deepI sections, oriented with the web transverse to the direction of the bridge.

All lateral, sway, and portal bracing is formed with angles. Top and bottom lateral bracing span one panel diagonally. Those on top are angles with lacing, but the bottom braces are single angles. Sway bracing at each panel point is a three-panel double-intersection Warren truss. Portal braces are trapezoidal with braces reaching from the center of the top strut to the inclined impost. A portal brace on the diagonal at the first vertical of the main span replaces the sway bracing at that point.

The 27-inch-deep I-beam floor girders are supported on the bottom chord and are riveted to the vertical web members. The girders support the 20 foot wide concrete slab deck with curbs without the aid of stringers.

June, 2017 at Pruitt Landing, west of/downstream from bridge(s)

My favorite memory of the Pruitt Bridge:  swimming just downstream from it when I was a kid, when a man named Hillary Jones owned the land north of the bridge and had a campground there.  You could pay for day use to go down to the river, where steps were carved in the bluff to facilitate the descent to the swimming hole.  The photos just above and below are from visits to Pruitt in recent years, where I went floating or kayaking with my son.  On the photo above, you can see the "PRUITT" sign in the background.

Summer 2015, Lower Pruitt Landing