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32 To convert the truck coordinate data to bridge coordinates Selecting Field Test Sites required inputting the profile line into the program before beginning data collection. The program was designed to allow Locating field test sites was predicated on finding states this to occur before arriving at the bridge, or it could be done willing to provide cooperation. This required more than just after setting up on the bridge. It was also necessary to mea- permission from the bridge owners to be on site, because there sure the horizontal and vertical offsets of the truck relative were also issues related to traffic control, assistance in locating to the profile line. A chisel mark on the rear bumper of the suitable test sites that met at least some of the defined criteria, truck was used as the point of reference, and both the dis- and providing bridge plans and scour history related to the tance from the pavement to that mark, and the horizontal structure. Willing participants were located primarily through distance from the profile line were measured and entered personal contact with states known to have an interest in scour- into the program. The vertical offset was manually corrected related issues. for the cross slope of the pavement (typically 2 percent) when A complicating factor in designing the field testing program entering that distance. With this information, the computer was the record drought conditions throughout much of the program automatically calculated and reported results in country in 2002. Figure 40 illustrates areas below normal bridge coordinates. moisture at the end of April 2002, when the selection and The software for sonar measurements with the crane scheduling of test sites was underway. This map is based on allows point measurements or continuous recording as the 7-day averages at given USGS gaging stations and provides a better indication of longer-term streamflow than either crane is either driven across the bridge or, with the truck in a real-time or daily streamflow data. Only stations with at least stationary position, sweeping the crane in an arc. The x,y,z 30 years of record are used, and the dots represent compar- data collected by sweeping the articulated arm with the truck isons of the 7-day average to percentiles of historical weekly in a stationary position can be used to develop bathymetric streamflow for the given week. The dots range from conditions plots using standard contouring programs. Cross-section data depicting below normal streamflow (lightest colored dots) to collected while driving the truck across the bridge can be extreme hydrologic drought (darkest colored dots). plotted in any x-y plotting program. The program also The below normal moisture conditions eliminated many included a calibration menu that allows calibrating all sen- states from consideration, even when there was a willingness sors, to compensate for any drift or changes in zero that to cooperate. For example, as indicated in Figure 40, most might have occurred either in transit or from environmental of the eastern and southern states were not good candidates, or use factors. as was also the case for many of the snowmelt-driven states Limited graphical presentation of the data is provided dur- throughout the west. ing data collection. A schematic of the crane provides a visual Initially, seven states were identified as possible candi- reference of the crane geometry for the operator. A running dates for detailed testing under Task 6 (i.e., Colorado, Nevada, plot of bed elevation versus time facilitates monitoring the California, Idaho, Alabama, Indiana, and Missouri). These scour depth measurements. states represented a wide range of flow conditions, from snowmelt-driven rivers, to rainfall-based floods, to tidally DETAILED FIELD TESTING influenced rivers and bays. Colorado, Nevada, California, and Idaho provided opportunities for snowmelt-driven rivers, pos- Objective sibly with some ice flow conditions. Alabama provided oppor- The objective of detailed field testing was to evaluate the performance of the articulated arm truck at various sites, representing a range of bridge and site conditions with the assistance and/or cooperation of at least two local or state transportation agencies. The purpose of this testing was to validate the performance of the prototype devices and/or pro- cedures under real-world conditions, as implemented by highway personnel. Ideally, detailed testing would occur during flood con- ditions to evaluate the performance of the articulated arm relative to the 12 criteria established as part of the research objective. In particular, this included a range of bridge conditions (e.g., high bridge decks and limited clearance) and flow conditions (e.g., high velocity and sediment concentrations, floating debris, ice, pressure flow, and air Figure 40. Locations of below normal streamflow at the entrainment). end of April 2002.
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33 tunities for tidally influenced conditions along the Gulf coast Ultimately, only Missouri and Indiana had any flooding of and rainfall-driven runoff in more inland areas. Indiana and significance. Missouri provided rainfall-driven flooding, with good possi- Despite these conditions, adequate testing was completed bility for high debris and suspended sediment loading. to verify the performance and operation of the equipment. After identifying possible states, the next objective was try- High-velocity conditions were found in western Colorado, ing to schedule site visits. The window of opportunity was rel- not because of flood flow but simply because of higher chan- atively short, given that the prime time for either rainfall- or nel gradient. Major flooding occurred in southern Indiana, snowmelt-driven flooding in the identified states was during and significant high water was found in Missouri. Other testing late spring to early summer (i.e., April through June). In order provided the opportunity to try the equipment on various to schedule as many visits as possible, it was decided to make bridge geometries and conditions, even though severe flow the initial site visits in the south and work north and west as conditions were not encountered. weather conditions warmed up. Therefore, the first scheduled Table 5 summarizes the locations and dates of field testing trip was to Alabama, however, based on a desire to map condi- that were completed. Table 6 summarizes the runoff condi- tions around a scour-critical pier that had just been riprapped, tions at the test sites, relative to the research criteria estab- prior to high flow occurring, several early season trips were lished for the project (as discussed in Chapter 1). Velocity also made to a bridge in western Colorado. conditions were estimated by timing floating debris passing Beyond general planning with each state, trips were not under the bridge or, in a few select locations, by actual cur- tightly scheduled in the hope that when flooding began, a trip rent meter measurements. Sediment concentrations were not could be made on relatively short notice. Flow conditions in measured, but were estimated from nearby gage data. No ice each state were tracked by regular phone calls to each state or debris conditions existed at any of the locations where data hydraulic engineer and by tracking reported conditions using were collected. Air entrainment conditions were based on a the NRCS Snotel network and the USGS streamgage network. qualitative assessment of flow conditions and turbulence in Unfortunately, as time passed, the drought conditions only the region of the measurements. Table 7 summarizes the geo- worsened. In many of the snowmelt-driven basins, low runoff metric conditions at the test sites, relative to the research cri- occurred even when snowpack levels were near normal. Dis- teria. No pressure flow conditions were encountered, and the cussions with NRCS hydrologists indicated that this trend was lowest clearance was 9 ft (2.7 m); but the articulated arm occurring because of overall low moisture conditions and, would have worked under conditions of little or no clearance therefore, much of the snowmelt was being absorbed into the (i.e., pressure flow), given the positioning capability of the ground. Furthermore, what runoff made it to the channels was arm. Similarly, no high bridges were tested, given that the typically being stored in reservoirs given water management most interest was in the capability of the articulated arm with issues related to the drought. In particular, this occurred in the streamlined sonar probe, and generally bridges where this Nevada, where the Truckee River peaked at a very low setup could be tested were selected. High bridges (more than value about 30 days before the long-term average peak flow 50 ft or 15 m) could have been measured using the winch sys- historically occurred. This also occurred in rivers draining the tem on the truck, which was tested on a bridge in Indiana. western side of the Sierras and in southern and eastern Idaho in the Snake River basin. In many of the precipitation-driven states, there were no Field Testing Results sustained storms producing widespread flooding conditions. Small, localized storms were occurring that generally kept Information in the following paragraphs summarizes the moisture and flow conditions from being in a drought cate- field testing completed and the major findings at each location. gory, but the overall runoff conditions were low and certainly Additional discussion on the field test results for each location not the flood-type conditions desirable for Task 6 testing. is provided in Appendix B. TABLE 5 Locations and dates of detailed field testing State River Bridge Date Colorado Colorado River I-70 near Debeque March 14 & 26, 2002 Alabama Heron Bay State Highway 193 April 3, 2002 Chickasaw Creek State Highway 213 April 3, 2002 Little Lagoon Pass State Highway 180 April 4, 2002 Minnesota Minnesota River State Trunk Highway 93 May 13, 2002 Wisconsin Wisconsin River State Trunk Highway 80 May 14, 2002 Missouri Grand River U.S. Highway 24 May 17, 2002 Indiana White River State Highway 61 May 22, 2002 Idaho Snake River Ferry Butte June 4, 2002 Shelley June 4, 2002
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34 TABLE 6 Runoff conditions at field test sites relative to the established research criteria River Discharge Velocity Conc Debris? Ice? Air (cfs) (fps) (ppm) Entrainment Colorado River 1,500 cfs at at I-70 USGS Gage 09095500 11 <2000 No No Medium (8 mi downstream) Heron Bay at SH 193 NA <3 <100 No No Low Chickasaw Creek at SH 213 NA <3 <100 No No Low Little Lagoon Pass at SH 180 NA 3 <100 No No Low Minnesota River 7,460 cfs at at STH93 USGS Gage 05330000 <3 <500 No No Low (20 mi upstream) Wisconsin River 22,900 cfs at At STH80 USGS Gage 05407000 <3 <200 No No Medium (located at bridge) Grand River 18,600 cfs at At US24 USGS Gage 06902000 6.5 <1000 No No Medium (25 mi upstream) White River 90,000 cfs at At SH61 USGS Gage 03374000 5 <1000 No No Medium (located at bridge) Snake River 2,890 cfs at At Ferry Butte USGS Gage 13069500 <3 <500 No No Low (located at bridge) Snake River 6,820 cfs at At Shelley USGS Gage 1306000 <3 <500 No No Low (located at bridge) TABLE 7 Geometric conditions at bridge Pressure Overhang Height River Clearance Flow or Projecting Above (ft) ? Geometry Water (ft) Colorado River at I-70 20 No Projecting riprap 15.5 pile around pier Heron Bay at SH 193 Projecting Piles 19 No (battered piles) 16 Chickasaw Creek at SH 213 Projecting Piles 9 No (battered piles) 6 Little Lagoon Pass at SH 180 Projecting Piles 18 No (battered piles) 15 Minnesota River at STH93 Deck Overhang 20 No (hammerhead pier 15 on piles) Wisconsin River At STH80 Slight Overhang 14 No (hammerhead pier 9 on spread footing) Grand River At US24 14 No Deck Overhang 9 (piles) White River At SH61 Deck Overhang 20 No (hammerhead pier 15 on piles) Snake River At Ferry Butte Projecting Pier on 16 No spread footing 12 Snake River At Shelley Projecting Pier on 20 No spread footing 16
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35 Colorado I-70 Bridge The I-70 Bridge across the Colorado River in DeBeque Canyon has been rated scour critical based on observed conditions (Item 113, Rating 2). The bridge was designed for a 50-year discharge of 32,000 (900 m3/s). The channel bed material is primarily gravels and cobbles. The upstream chan- nel bend has migrated, creating a skewed alignment into the bridge opening and a large scour hole at Pier 2 that extends through the bridge opening to the downstream side. Prior to extensive riprap placement in mid-March 2002, a 20 ft (6.1 m) scour hole had developed, exposing about 10 ft (3.0 m) of pile. Figure 41 shows the bridge from the upstream side, with Pier 2 on the right side where the articulated arm truck is parked. Flow conditions between Pier 2 and the right abutment are shown in Figure 42. At about mid span, the velocities were 11 fps (3.3 m/s), and the flow depth was about 6 ft (1.8 m). Data were collected on the downstream side by positioning the truck to the right of the pier where the scour hole had been and sweeping multiple arcs (Figure 43). The Colorado testing was the only test site that provided high-velocity conditions, and the articulated arm proved to be quite stable. This site also provided an early opportunity to test various components of the truck and articulated arm system. Figure 42. Flow conditions between the right abutment This testing resulted in refinement in the data collection pro- and Pier 2. gram and incorporation of filters on the wireless data to mini- mize radio interference problems. site visit, but, unfortunately, no additional rain occurred. The trip was timed to coincide with predicted strong tidal Alabama Bridges conditions, but that too was moderated by unexpected off- shore winds. Therefore, flow conditions were not as strong Three bridges were visited in the Mobile, Alabama, area as expected, but the testing was still valuable because it over a 2-day period. These bridges were all in tidal, or tidally provided the opportunity to use the equipment and identify influenced, channels and were selected to investigate the use necessary changes and improvements early in the testing of the truck in this type of environment. This also provided program. an opportunity for additional early runoff season testing prior to the start of more rainfall-driven runoff events in other parts of the country. This area had received rain during the week prior to the trip, and more showers were forecast during the Figure 43. Using the crane to sweep arcs on downstream Figure 41. Interstate 70 bridge across DeBeque Canyon. side of Colorado River bridge.
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36 All three bridges were similar in design, with two lanes and tunity to test the 5 ft (1.5 m) extension on the end of the artic- a pile foundation (Figure 44). The bridges at Little Lagoon Pass ulated arm and the ability of the fin to swivel freely and track and Chickasaw Creek did not have shoulders and required the current on its own. This was also the first field test of a traffic control which was provided by the Alabama DOT. cross-section measurement by driving the truck with the cas- Heron Bay had a shoulder with adequate room for the truck tors down. Based on these tests, the streamlined probe was (Figure 45). The Alabama bridges provided the first oppor- redesigned, and an improved method of mounting the castor was developed. 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. At the time of the inspection, runoff was low and there were no known scour problems. Figure 46 shows the approach conditions to the bridge, and Figure 47 shows the truck in position to measure conditions at Pier 1. This site allowed testing of the new ex- tension for the sonar stabilizer with the pivot point further for- ward on the blade and the new castor system for cross-section measurements. Figure 44. Little Lagoon Pass bridge. Figure 46. Upstream conditions at Minnesota TH93 across the Minnesota River. Figure 45. Truck position on the Heron Bay bridge, Highway 193 near Daulphin Island. Figure 47. Truck positioned at Pier 1, Minnesota TH93.
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37 Wisconsin State Highway 80 scour problems. Missouri had received significant rainfall in the week prior to the inspection, but most of the smaller Wisconsin STH 80 crosses the Wisconsin River near Mus- drainages had already peaked. The Grand River watershed coda, Wisconsin. The bridge has nine spans on eight hammer- is large and flow conditions at this bridge were still quite head piers supported by spread footings. The bridge has had high at the time of inspection, with velocities around 7.0 fps scour problems at Pier 1, which is in an eddy along the left (2.1 mps). Figure 50 shows the truck position on the bridge bank creating reverse-flow conditions at the pier. Figure 48 to collect data at Pier 5, and Figure 51 shows the sonar in shows conditions at Pier 1 on the upstream side of the bridge the water. as arc measurements were being made. This bridge provided the first opportunity to test the kneeboard on a rigid frame (Fig- ure 49). Knowing the location of the end of the crane, the angle Indiana State Route 61 of the rotator, the length of the frame, and the distance to the Indiana S.R. 61 crosses the White River southeast of water surface, the position of the kneeboard could be calcu- Vincennes, Indiana. The bridge has five spans on piers with lated as it was moved under the bridge. During testing, the pile caps with steel H piles driven to approximate refusal. framework was damaged, leading to a revised design. At the time of inspection, the river was at flood stage and the southern part of the state was experiencing the wettest Missouri U.S. Highway 24 May on record. Figure 52 shows the bridge and the flood stage conditions. The bridge has not had any major scour U.S. Highway 24 crosses the Grand River near Brunswick, problems, but has had a large sand bar in the bridge open- Missouri. The bridge has seven spans on six piers, two of ing that had been contracted for removal. In addition to which have been protected with gabion baskets in response to potential pier scour during the recent high flows, the Indi- ana DOT was particularly interested to see if the sand bar was still present. Testing at this bridge provided the opportunity to work at flood stage with relatively high velocities (about 7 fps or 2.1 mps). The bridge had large grate inlets that required posi- tioning the truck away from the barrier for a cross-section mea- surement. This had not been tried before, but worked well because the crane could still be articulated into position. The wireless sonar in the sounding weight was also tested at this bridge (Figure 53) and was found to track the current and remain in a steady position, which had been a problem with ear- lier versions of the modified sounding weight. Figure 48. Arc measurements on the upstream side of Idaho Bridges Wisconsin STH80, pier 1. 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 Figure 49. Kneeboard in the water before being pushed under Wisconsin STH80 bridge. Figure 50. Truck in position at U.S. 24, Missouri.
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38 Figure 53. Sounding weight with a wireless sonar being tested in Indiana. footing piers. The deck width was 33 ft (10.0 m) with no shoul- der, requiring a lane closure for traffic control that was provided by Bingham County. Figure 54 shows the bridge at Ferry Butte. Arc measurements were made at the upstream side of the piers at both bridges, supplemented by kneeboard mea- surements at Ferry Butte and a cross section at West Shelley. High-velocity and turbulent conditions existed near the piers (Figure 55), but the crane and the streamlined probe were quite stable. These bridges allowed testing an improved kneeboard (Figure 56), as well as running the castors through sand and gravel that had collected along the curbline. Figure 51. Arc measurement at pier 5, U.S. 24. Reduction of Data from Field Tests scour problems in the past and were of interest to the Idaho As described above, various data were collected at each DOT. Additionally, they were going to install A-jacksTM as bridge using different deployment methods from various a countermeasure later in the year and were interested in hav- locations on the bridge deck. During each measurement, bed ing a pre-construction survey. The bridge design for the Ferry conditions could be monitored on the computer, either as a Butte Bridge, south of Blackfoot, and the West Shelley Bridge, scrolling graph of bed conditions or in tabular format. How- north of Blackfoot, were similar, with four spans on spread Figure 54. Ferry Butte bridge across the Snake River, Figure 52. Indiana SR61 at flood stage. Idaho.
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39 Figure 55. High-velocity conditions near the pier at West Shelley, Idaho. ever, once a measurement was completed, the computer soft- ware also produced an archived x,y,z data file in bridge coordinates. This data file could be used by various plotting and/or contouring programs to provide a detailed graphical representation of the data. Figure 57 shows data collected at the upstream side Indi- ana State Route 61 over the White River. The data were reduced in MicrostationTM, but any similar program would produce comparable results. The basic bridge geometry was included, using information provided on the bridge plans. At this location, both arc measurements in front of the piers and a cross section measurement were taken. Similar graphs for all other bridges visited are included in Appendix B. Figure 56. Kneeboard with revised frame.
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Figure 57. Typical results obtained with the articulated arm.