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Portable Scour Monitoring Equipment (2004)

Chapter: Appendix B: Field Testing Results

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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
×
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
×
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
×
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Suggested Citation:"Appendix B: Field Testing Results." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
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B-1 APPENDIX B FIELD TESTING RESULTS Colorado Field Testing The I-70 bridge across the Colorado River in DeBeque Canyon has three piers on pile caps with 12 H-piles under each pile cap. The total width is 40.5 ft (12.3 m) consisting of two 12 ft (3.7 m) driving lanes, a 10 ft (3.0 m) shoulder on the right, a 4 ft (1.2 m) shoulder on the left and curb sections with Type 3 bridge rail (15 inches (0.4 m) wide). The first site visit to this bridge was made during the week of March 8 as the temporary road into the channel was being built for placing additional riprap. Some riprap had been placed previously by end dump- ing from the bridge, but Colorado DOT was unable to fill the scour hole completely. Therefore, they were building a rock road into the channel to allow more direct placement of rock. Data collection was attempted during this first trip using the crane system, but the computer kept locking up. This may have been caused by a cell phone tower just upstream of the bridge scrambling some of the data during wireless transmission from the end of the crane. The software was subsequently modified to filter for bad data, and on a return trip during the last week of March, data were collected on both the upstream and down- stream sides of the bridge from Pier 2 to the right abutment (defined looking downstream). Colorado DOT provided traf- fic control during both trips. Data was collected on the downstream side by positioning the bridge to the right of the pier where the scour hole had been and sweeping multiple arcs (Figure B1). Data were collected on the upstream side with the truck positioned at the centerline of Pier 2 and about midway between Pier 2 and the abutment (Figure B2). Figure B3 shows the articulated arm being low- ered into position. The instrument shelter with the computer and other instrumentation is shown in Figure B4, as is one of the two post-mounted winches. The instrument box at the end of the crane is being wired for operation in Figure B5. Fig- ure B6 shows one of the two winches being used to suspend the sounding weight, and the Marsh-McBirney velocity sensor on a 50-lb (24-kg) weight is shown in Figure B7. Based on the data collected, a plot of the bathymetry was developed for the area upstream and downstream of Pier 2 (Fig- ure B8). CDOT was interested in the riprap placement, because it had to be done underwater in high-velocity conditions. Based on the bathymetry, the scour hole was filled with rock. Alabama Bridges Three bridges were visited in the Mobile, Alabama, area. The Heron Bay Bridge, a five-span bridge on State Highway 193 leading to Dauphin Island, is scour critical based on cal- culations. The bridge is a two-lane structure with wide-enough shoulders to park the truck without additional traffic control (Figure B9). Cones and signs carried on the truck were used, and an Alabama DOT vehicle was parked on the approach with its lights flashing. Figure B10 shows a measurement being made by sweeping the crane in an arc movement in front of the pier. Multiple arcs were taken to completely map the area approaching the pier from the Gulf side. The Chickasaw Bridge is a four-span structure taking State Highway 213 across Chickasaw Creek in northwest Mobile. This bridge is tidally influenced and was rated scour critical based on calculations. There were no shoulders and data col- lection required a lane closure, provided by Alabama DOT. Figure B11 shows the sonar in place to begin a measurement at a pier. Figure B12 shows the positioning of the stabilizers, with one on the deck and one on the curb. The Little Lagoon Pass Bridge is a six-span bridge on State Highway 180 near Gulf Shores, Alabama. The bridge is in a constricted tidal inlet that historically has had significant sed- iment movement and relatively high velocities because of the constriction created by the seawalls. The bridge has had some scour problems because of the velocities, while the entire bridge reach in the inlet area has had sediment deposition prob- lems, requiring dredging. Alabama DOT had expected rela- tively high tidal velocities at this bridge, but after several hours of waiting on the bridge for the cross over point between low and high tide, when the velocities would be highest, measure- ments found the maximum velocities on this day to be about 3 fps (0.9 m/s). Velocity measurements were made with a Marsh-McBirney current meter attached to the end of the crane (Figure B13). For this bridge, the extension was taken off the sonar to allow mounting the current meter as shown. The veloc- ities and stream power were high enough to create ripples and some dune movement of the bed but no significant scour at the piers. Figures B14a through c provide plots of the data collected at these bridges. Minnesota Trunk Highway 93 Bridge Minnesota Trunk Highway 93 (TH93) crosses the Min- nesota River near LeSueur, Minnesota. The bridge has five spans on four piers on a pile foundation. The total width is 46 ft, 2 in. (14.1 m) consisting of two 12 ft (3.7 m) driving lanes, two 9 ft, 5in (2.9 m) shoulders and an 18 in. (0.46 m) barrier railing. Given the drought conditions in Minnesota, the bridge was visited primarily to demonstrate the equipment to Minnesota DOT and to complete initial testing of components that had been modified since the Alabama trip. This included the new

B-2 lowered, takes only minutes to deploy. Figure B17 shows the truck ready for a cross-section measurement, with the castors in place and the surveyor’s wheel on the ground. Figure B18 plots the data collected at these bridges. Wisconsin State Highway 80 Wisconsin STH 80 crosses the Wisconsin River near Muscoda, Wisconsin. The bridge has nine spans on eight Figure B1. Crane on downstream side of bridge near scour hole. Figure B2. Using the articulated arm to sweep arc’s on the upstream side of bridge. Figure B3. Looking down the articulated arm as the sonar is being positioned in the water. Figure B4. Collecting data. extension for the sonar stabilizer with the pivot point further forward on the blade and the new castor system for cross- section measurements. At the time of the inspection, runoff was low and there were no known scour problems. The inspec- tion was completed on May 13, 2002, and included arc mea- surements at Pier 1 and a cross section on the upstream side of the bridge. Minnesota DOT provided traffic control. Figure B15 shows the truck in position to measure condi- tions at Pier 1. The new stabilizer blade performed well and was able to track the current, even given low-velocity condi- tions. Figure B16 shows the improved castor system used to allow truck movement with the crane deployed. This system was not quite as rigid as the original turnbuckle design, but was much easier to deploy. The turnbuckle system took about 30 minutes to set up, while the new system, with the castor on an arm that can swing in place under the outrigger before it is

hammerhead piers supported by spread footings. The total width is 42 ft (12.8 m), consisting of two 12 ft (3.7 m) driving lanes, two 6 ft (1.8 m) shoulders, and 18 in. (0.46 m) parapets. The bridge has had scour problems at Pier 1, which is in an eddy along the left bank creating reverse-flow condi- B-3 tions at the pier. The inspection was completed on May 14, 2002, and included arc measurements at Pier 1, a cross sec- tion from Piers 1 to 3, and kneeboard measurements to get further under the bridge deck at Pier 1. Wisconsin DOT provided traffic control. Figure B19 shows the sonar in the water on the upstream side of Pier 1. Note the orientation of the stabilizing fin in Fig- ure 20, which indicates the reverse-flow condition at this pier. Figures B20 through B22 illustrate the deployment of the kneeboard on a rigid frame to get under the bridge. The frame was made of aluminum and connected to the rotator on the end of the crane. Knowing the location of the end of the crane, the angle of the rotator, the length of the frame, and the distance to the water surface, personnel can calculate the position of the kneeboard as it is moved under the bridge. During this field trial, as the kneeboard was being swept side-to-side under the bridge with the hydraulic rotator, the frame was bent as the flow line between the main flow and the reverse flow was crossed. A software problem was also dis- covered in the position calculation for this method during this test. A stiffer, simple frame was designed after this event and the software was revised, prior to additional testing in Idaho (see below). Figure B23 plots the data collected at these bridges. Figure B5. Instrument box on end of crane. Figure B6. Using a single winch to position sounding weight with Marsh-McBirney. Figure B7. Marsh-McBirney velocity sensor on a 50 lb sounding weight.

B-4 Figure B8. Colorado I-70 results. Figure B9. Heron Bay bridge, Highway 193 near Daulphin Island. Figure B10. Making an arc measurement on the Gulf side of the bridge. Missouri U.S. Highway 24 U.S. Highway 24 crosses the Grand River near Brunswick, Missouri. The bridge has seven spans on six piers, two of which have been protected with gabion baskets because of scour problems. The bridge is about 47 ft (14.3 m) wide, with two 12 ft (3.7 m) lanes, two 10 ft (3.0 m) shoulders and 18 in (0.46 m) barrier rails. The inspection was completed on May 17, 2002. Missouri had received significant rainfall in the week prior to the inspec- tion, but most of the smaller drainages had already peaked. After visiting several bridges around the Macon area that were on smaller drainages and finding little flow in the channels, this bridge was selected to evaluate the performance of the gabion baskets during and after a large flow event. The Grand River

watershed is large, and flow conditions were still quite high at the time of inspection, with velocities around 7.0 fps (2.1 m/s). Based on the time available and a large debris snag at Pier 6, measurements were completed only at Pier 5. Figure B24 shows the approach conditions to the bridge. Figure B25 illustrates an arc measurement at full extension. Figure B26 plots the data collected at these bridges. Indiana State Route 61 Indiana S.R. 61 crosses the White River southeast of Vincennes, Indiana. The bridge has five spans on piers with pile caps with steel H piles driven to approximate refusal. The bridge was designed for a 100-year flow of 114,810 cfs (3,250 m3/s). At the time of inspection, May 22, 2002, the river was at flood stage, and the southern part of the state was experiencing the wettest May on record. The bridge has not had any major scour problems, but had a large sand bar in the bridge opening that had been con- B-5 Figure B11. Crane in position at the Chickasaw Bridge. tracted for removal. In addition to potential pier scour during the recent high flows, Indiana DOT was particularly inter- ested in seeing if the sand bar was still present and asked that the research team survey both the upstream and downstream sides of the bridge. Figure B27 depicts the bridge deck, which was 48 ft, 4 in. (14.7 m) wide, with 12 ft (3.7 m) lanes, 10 ft, 8 in. (3.2 m) shoulders, and 18 in. (0.46 m) concrete barrier wall. Traffic control was provided by Indiana DOT. Figure B28 illustrates conditions on the upstream side of the bridge. Figure B29 shows the cross-section measurement being taken on the upstream side, and Figure B30 shows the sonar in the water as the measurement is being made. The truck had to be positioned away from the concrete barrier to avoid run- ning the castors over the drainage inlets (Figure B31). How- ever, this did not create a problem as the arm was articulated into an acceptable position for the cross section. Figure B32 shows an arc measurement on the downstream side of the bridge. Note the wake indicating the strength of the current, which was flowing about 6.8 fps (2.1 mps). The wireless sonar mounted in a 75 lb (34 kg) sounding weight was tested at this bridge. The sounding weight was sus- pended by a 4 ft (1.2 m) hanger bar with the electronics (wire- less modem) enclosed at the top of the hanger bar (Figure B33). The sonar is embedded in the bottom of the sounding weight, with a small wedge to better transition flow over the transducer face (Figure B34). This was necessary given that most sound- ing weights are not streamlined on the bottom, but are designed with a flat bottom so they are stable when set on the ground for rigging current meters. The flat-bottom design could create a separation zone off the nose of the sounding weight, which would not be an issue for current meter applications but was a concern when mounting a sonar transducer in the bottom of the weight. Figure B35 plots the data collected at these bridges. Figure B12. Positioning the stabilizer on the curb line. Figure B13. Marsh-McBirney current meter mounted on the crane upstream of the sonar. (text continues on page B-9)

Figure B14a. Heron Bay results.

Figure B14b. Chickasaw Creek results.

Figure B14c. Little Lagoon Pass results.

B-9 Idaho Bridges Two bridges on the Snake River were visited near Black- foot, Idaho. The drought conditions limited runoff in the state, particularly in eastern Idaho; however, these bridges have had scour problems in the past and were of interest to Idaho DOT. Additionally, they were going to install A-jacks™ as a coun- termeasure later in the year and were interested in having a sur- vey prior to construction. Both the Ferry Butte Bridge, south of Blackfoot, and the West Shelley Bridge, north of Blackfoot, were visited on June 4, 2002. The bridge design for both structures is similar, with four spans on spread footing piers. The deck width was 33 ft (10.1 m) with no shoulder, requiring a lane closure for traf- fic control that was provided by Bingham County. Arc mea- surements were made at the upstream side of the piers at both bridges, supplemented by kneeboard measurements at Ferry Butte and a cross section at West Shelley. Given narrow bridges with no shoulder, placement of the truck on the bridge deck at these bridges (Figure B36) was similar to the Chickasaw Bridge in Alabama. Figure B37 shows an arc measurement in process on the upstream side. After problems with the kneeboard frame in Wisconsin, a revised frame was developed. The revised frame was made of steel (the original was aluminum) and was more rigid and also allowed the kneeboard to swivel, similar to the concept used on the sonar stabilizing fin. The frame was tested at the Ferry Butte Bridge and worked better than the original design, but the kneeboard/frame was still somewhat difficult to get ini- tially placed in the flow and then pushed under the bridge. Fig- ure B38 shows the kneeboard along side the pier wall at the bridge. The software revisions made after the Wisconsin bridge to calculate the position of the kneeboard did correct the posi- tion problems that existed. Figure B39 shows an arc measurement near a pier at the West Shelley Bridge. Even at low flow, the local velocity and turbulence near the piers were significant. An accumulation of gravel and sand along the curb line on this bridge was a concern in terms of the castors during the cross-section measurement, but the neoprene wheels rolled through this material with no problems (Figure B40). Figure B41 plots the data collected at these bridges. Figure B15. Making measurements at Pier 1. Figure B16. Close-up of stabilizer sitting on castor. Figure B17. Cross section measurement with castors deployed and survey wheel in place to measure distance traveled.

Figure B18a. Minnesota Trunk Highway 93 cross section results.

Figure B18b. Minnesota Trunk Highway 93 pier 1 results.

B-12 Figure B19. Arc measurement on the upstream side of Wisconsin STH80. Figure B20. Kneeboard on a rigid frame. Figure B21. Deploying the kneeboard. Figure B22. Kneeboard under the bridge.

Figure B23a. Wisconsin State Highway 80 cross section results.

Figure B23b. Wisconsin State Highway 80 pier 1 results.

B-15 Figure B25. Arc measurement at full extension. Figure B24. Approach conditions at U.S. 24, Missouri

Figure B26. Missouri Highway 24 results.

B-17 Figure B27. SR 61 crossing the White River in Indiana. Figure B28. Upstream conditions at S 61. Figure B29. Measuring a cross section at SR 61. Figure B30. Sonar in the water as the truck is moving across the bridge during a cross section measurement.

B-18 Figure B31. Truck positioned to clear grate during cross section measurement. Figure B32. Arc measurement on downstream side. Figure B33. Sounding weight with sonar. Figure B34. Close up of sounding weight showing wedge on leading edge of sonar.

Figure B35. Indiana State Route 61 downstream side results.

B-20 Figure B36. Truck placement at Ferry Butte. Figure B37. Arc measurement on upstream side. Figure B38. Kneeboard under bridge at Ferry Butte. Figure B39. Arc measurement upstream at West Shelley. Figure B40. Castor movement through sand and gravel deposited along curbline.

Figure B41a. Ferry Butte results.

Figure B41b. West Shelley cross section results.

Figure B41c. West Shelley pier results.

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TRB's National Cooperative Highway Research Program (NCHRP) Report 515: Portable Scour Monitoring Equipment presents the findings of a research project undertaken to develop portable scour monitoring equipment for measuring streambed elevations at bridge foundations during flood conditions. The report provides specific fabrication and operation guidance for a portable scour monitoring device.

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