 Nestled in southern Hickory County, deep in the Missouri Ozarks, lies the beautiful Pomme de Terre Lake. This lake was completed in 1961 by the Corps of Engineers. The lake was designed to be a part of a comprehensive flood control plan for the Osage River Basin, but it has developed into much, much more. We have boating, swimming, fishing, hunting, and camping. Pomme de Terre has become an outdoor recreation paradise for Missourians and visitors from all over. Construction of the Route 64 bridge over the Lindley Creek Arm of the Lake near Nemo, Missouri, was completed in 1960. The bridge, sometimes referred to as the Nemo Bridge, is a major artery for access to the local marinas and businesses, which cater to visitors year-round. Approximately 2,300 vehicles cross the bridge every day. Eventually, normal deterioration took its toll on the bridge deck, compelling MODOT to take action. However, the project team was faced with several challenges. The decision was made to use the casting place method to replace the bridge deck. The problem with doing this was that the construction period would be two years and would overlap through a winter month. The 1,684-foot length and the narrow 22-foot width would complicate traffic handling during construction. Weight and lane width restrictions would not allow fire trucks, ambulances, school buses, and large recreational vehicles to use the bridge during replacement of the deck. The shortest state route detour was approximately 31 miles in length. The local communities and surrounding area depend heavily on tourism, and the public was very concerned about the length of time their lives and businesses would be disrupted. Dave O'Connor, our district maintenance bridge engineer, had attended a precast concrete conference. At that conference, he came up with some ideas that he thought could be applied to the Route 64 bridge project. At that conference, there were several presentations that dealt with the rapid replacement of decks and superstructures. Watching these and seeing the fact that other states had been able to get this done, it seemed that we should be able to do something and this may be the perfect case to put that into practice. I came back to the district after the conference and after a short period of time, I took the information that I gained there and I went to the project development engineer, spoke to him. We discussed it and came to the conclusion between ourselves that this at least should be pursued and researched as to its applicability to this particular bridge. He forwarded the information and the idea to the consultant on this project, HNTB. As soon as we talked about that concept that really got me interested and we started looking into it a little bit more. We were already done 90% completion with the plans so it was a slight backtrack. So we were a little bit hesitant but then we saw this opportunity to cut down the construction time from two years to almost six months with practically no inconvenience to the traffic. We jumped right on it to go ahead and do the more research. We sat down with the contractors, we sat down with precast fabricators, we also talked with the university professors and to evaluate to see if this concept could be applied, the material availability was there to go ahead and take that concept to the reality. A casting bed 29 foot wide by 360 foot long was built on a nearby abandoned quarry just south of the project. Unlike building a regular bridge deck in place where long lengths can be ready for pouring the concrete, this job required 164 individual 10 foot panels. For panel construction jigs were made to help place the two layers of reinforcing steel. Then eight tubes had to be cast into the concrete to hold the PT or post tensioning bars that would secure the panels together. Foam block outs were needed to create pockets where shear studs would connect the panels to the structural steel girders. Pockets were also needed around the ends of the PT bars to allow for tensioning after the panels were set. Later the pockets would be filled with grout. A process called match casting was used. After the first panel was poured the forms were removed from the edge that would butt up to the next panel. The adjoining edge had the concrete for the second panel poured against the keyway that was originally formed in the first panel so that the pieces would fit together perfectly. The joint between the two panels had a release agent applied to it so when the concrete cured they could be separated. Each adjacent panel was formed in the same way until the pieces for that continuous span were complete. To get the panels apart on the casting bed two hydraulic jacks were used to push against the pipes stuck in the shear studs block outs of the opposing panel. The panels were boomed off the casting bed and stored until needed at the project site. This casting practice was done five times for each continuous section of bridge which ranged from 270 foot long to 350 foot. The bridge's new deck would consist of 4.4 million pounds of precast concrete panels. I think the job was a success basically because MODOT really doesn't run casting yards quite the way this one was run. It was run a lot more like a construction project and it went basically flawlessly. We had a few kinks along the way but overall 164 and only one bad is a pretty good ratio. To speed up the setting CC&G built six temporary 10 foot bridge spans using small steel eye girders and open steel great deck to match the decking removed. They were built to match the 27 foot width of the new deck panels so the only width transition was from the temporary deck to the existing deck. Pieces were put in manually every night to make a smooth transition from the pre-installed guardrail on the temporary deck to the old guardrail. The temporary decking it allowed us to have more of an assembly line type construction rather than the deck crew waiting on the demolition crew and then the grouting crew waiting on the decking crew and one had to be completely done before the other could start. By utilizing the temporary decking and temporary railing we were allowed to close the bridge at 7pm and a lot of nights we were setting new deck panels by 8.30. The deck is held in place by steel shear studs welded to the top of the eye girders. The concrete was poured over the rebar and the shear studs which connected the deck to the girders. This design is called composite construction which helps the deck work with the eye girders superstructure so that the bridge can hold more weight. These studs had to be located and concrete around them removed. Large concrete saws were also used to cut through the 7 inch thick deck and the curbs to get them in movable sections. Then a crane would lift out the old deck. The tops of the girders were cleaned off and the old shear studs removed. Finally fast drying epoxy paint was applied to the tops of the girders. The crown of the roadway was formed into the concrete deck panels on the casting bed. When the panels were placed on the four girders the height or haunches over the girders had to be set and the difference filled in with fast setting high strength grout. Columbia Kirkman gutter came up with several ideas that helped the job go along. One was an angle iron support system to set the panels on. It acted as a formwork for the grouting operation. They'd set them down to the template on them, raise it to grade, get them right, set the panels on and they were ready to go. Slow setting epoxy concrete glue was used on each matched face of the concrete deck panel before the bar for post tension to seal the joints. Then either two or three of the new panels were tied together with PT bars. There are eight PT bars across the width of each panel that needed to be tensioned to 90,000 pounds per bar. The bars were tensioned two at a time using special hydraulic jacks until all were tensioned. Two jacks were used to tension the bars to keep tension equal across the face of the concrete sections. After the panels were set, new shear studs were welded on the top of the girders through the block outs left when casting the panels. Last, the haunches were grouted through the shear connector pockets each night after the panels had been post tensioned. The grout was required to reach 4,000 psi strength. The grout set up within a couple of hours so that the deck could be opened to traffic at 7 o'clock a.m. the next morning. After each span of bridge deck was installed, the contractor came back and filled the block outs around the PT bars with grout. The contractor reused the old posts and channel rails as a temporary guard rail from the new deck panels to the original guard rail. He also added a bottom rail to protect the rebar cast into the panels for the new concrete barrier curb. After all the deck panels were set in place, there were closure pores needed between the continuous spans at the piers. These concrete pores were done on the bridge where expansion joints were being replaced and filled in the gaps between the end of the deck panels and the expansion joints. These pores were done one lane-width at a time and then covered with a steel plate allowing traffic to pass over them. Once these closure pores were in place, the permanent reinforced concrete barrier curb was poured by the slip form method. The barrier was started on the west end of the bridge even before all of the panels had been finished being placed on the north end just before Labor Day. The remaining rebar for the top of the barrier was tied during the day and the concrete poured at night. A one and one half inch thick silica fume modified concrete overlay was placed as the final wearing surface. This overlay would keep any water and salt from getting into the precast concrete panels and would also even out the riding surface of the bridge. It was placed half a deck-width at a time to allow one lane of traffic to be open while the concrete cured for seven days. It was also placed at night to make sure the special silica fume concrete could be placed, finished, and initially cured correctly. Silica fume is a very fine powder that is a waste product from making electronic grade silicon that is used in making computer chips. The silica fume powder, with particles as fine as cigarette smoke, is substituted for some of the cement in the concrete and fills in all the pores in the mix, making it very dense and impervious to water and chloride ions and salt, which can deteriorate the concrete. The first two precast deck sections were placed on the south end of the bridge on Sunday night, June 27, 2004. Thirty foot of old deck had been removed the week before and replaced with temporary bridge deck sections. The last six precast panels were set on Tuesday, August 31, 2004 to finish the job two nights earlier than allowed by the contract. The first section of the one and one half inch thick silica fume overlay was placed on the southwest end of the bridge on the night of September 7, 2004. CCNG actually used 53 of 66 nights allowed in the contract to completely close the bridge from 7 o'clock p.m. to 7 o'clock a.m. on Sunday through Thursday from Memorial Day to Labor Day. There was almost no disruption to boat traffic since the channel was only closed at night when the barge had to be in the channel. When the bridge deck overlay and approach pavements are complete, the partial closings will be done, allowing unimpeded traffic before November 30, 2004. This will complete the project in less than one season with only a limited effect on busy vacation traffic. It will deliver a wider driving surface and a thicker deck, which should last for 30 to 40 years. This project would have taken at least two construction seasons of one-way traffic on the bridge if the deck had been repaired in place using conventional methods. I think this project, like you say, is about to wind up. I think it was a huge success. It did what we hoped it would do. Yes, I think it can be used in the future. If the circumstances are right, this bridge had an extraordinary length and narrow width, so traffic could not be shifted over while you cast in place. So maybe another bridge similar to that, this would be a good procedure to use. And another reason I think it was a huge success is the reaction we got from the community of the barge. When this project started, MODOT was very good to the community for having public meetings and explaining how everything was going to come together. And everyone was allowed to ask questions and they got the answers that they were hoping for. The bridge has never been shut down except at night, so therefore everyone was able to do their daily routine of business. Our visitors were able to get to our resorts, motels, our campgrounds. And at our last chamber meeting everyone felt that they had seen no disruption at all. We're very excited about this concept and really taking that to the reality. And I hope this becomes the future standard in the industry where we can do this thing overnight and try to cause the least inconvenience to the people and the community.