Bridge Scour Monitoring Methods at Three Sites in Wisconsin

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Bridge Scour Monitoring Methods at,Three Sites in Wisconsin. By John F Walker and Peter E Hughes, In cooperation with the Wisconsin Department of Transportation and the. Marathon County and Jefferson County Highway Departments. Open File Report 2005 1374,U S Department of the Interior. U S Geological Survey,U S Department of the Interior. Gale A Norton Secretary,U S Geological Survey,P Patrick Leahy Acting Director.
U S Geological Survey Reston Virginia 2005,For product and ordering information. World Wide Web http www usgs gov pubprod,Telephone 1 888 ASK USGS. For more information on the USGS the Federal source for science about the Earth its natural and living. resources natural hazards and the environment,World Wide Web http www usgs gov. Telephone 1 888 ASK USGS, Any use of trade product or firm names is for descriptive purposes only and does not imply endorsement by the. U S Government, Although this report is in the public domain permission must be secured from the individual copyright owners to.
reproduce any copyrighted materials contained within this report. Abstract 1,Introduction 1,County Highway B Bridge Crawfish River 2. Balsam Road Bridge Big Eau Pleine River 2,Wisconsin Highway 35 Bridge Tank Creek 4. Discussion 7,Pros and Cons 8,References Cited 8, 1 Map showing the location of the three sites with bridge scour monitoring 2. 2 Photograph showing wire weight gages on the County B bridge over the. Crawfish River in Jefferson County Wisconsin 3, 3 Photograph showing the Balsam Road bridge over the Big Eau Pleine River. in Marathon County Wisconsin 3, 4 Photograph showing the Wisconsin Highway 35 bridge over Tank Creek in.
Trempealeau County Wisconsin 4, 5 Photograph showing the transducer mount on the upstream edge of the. pier Tank Creek installation 4, 6 Graph showing scour measurements at the County B bridge over the Crawfish. 7 Graph showing continuous scour record from the upstream transducer at. the Balsam Road bridge over the Big Eau Pleine River for A a small storm. in April 1999 and B several flow events in July 1999 6. 8 Graph showing continuous scour measurements from the upstream. transducer at the Wisconsin Highway 35 bridge over Tank Creek 7. Conversion Factors and Abbreviated Units of Measure. Multiply By To obtain,inch in 2 54 centimeter cm,foot ft 0 3048 meter m. mile mi 1 609 kilometer km, cubic foot per second ft3 s 0 02832 cubic meter per second m3 s. pound avoirdupois lb 0 4536 kilogram kg,Bridge Scour Monitoring Methods at Three Sites.
in Wisconsin,By John F Walker and Peter E Hughes, Abstract potential NBI Item 113 are described in a Federal High. way Administration report Richardson and Davis 2001. Of the nearly 11 500 bridges in Wisconsin 89 have Values for NBI Item 113 that are 3 or less indicate critical. been assessed with critical scour conditions The U S scour conditions In Wisconsin 87 bridges inventoried. Geological Survey in cooperation with the Wisconsin were rated a scour code of 3 critical scour conditions. Department of Transportation the Marathon County and 2 bridges were rated a scour code of 2 critical scour. Highway Department and the Jefferson County Highway conditions with evidence of extensive past scour The. Department performed routine monitoring of streambed scour conditions at 1 583 bridges are unknown. elevations for three bridges Two monitoring approaches Scour monitoring can serve as a valuable counter. were employed 1 manual monitoring using moderately measure tool that provides WisDOT and County Highway. simple equipment and 2 automated monitoring using Departments with an essential element for plans of action. moderately sophisticated electronic equipment The results for bridges with scour critical conditions or unknown. from all three sites demonstrate that both techniques can foundations In November of 1997 the U S Geological. produce reasonable measurements of streambed elevation Survey in cooperation with the Marathon County Highway. The manual technique has a lower annual operating cost Department and WisDOT began a pilot project to monitor. and is useful for cases where documentation of long term bridge scour at the Balsam Road bridge over the Big Eau. trends is desired The automated technique has a higher Pleine River in Marathon County Wisconsin This effort. annual operating cost and is useful for real time monitor was undertaken as a follow up to a report describing the. ing of episodic events with short time durations scour potential of the bridge Parsons Brinckerhoff Quade. Douglas Inc 1997 In April of 2000 the U S Geologi, cal Survey in cooperation with WisDOT began monitor. ing bridge scour at the Wisconsin Highway 35 bridge over. Introduction Tank Creek in Trempealeau County Wisconsin In October. There are nearly 11 500 bridges spanning the mul of 2002 the U S Geological Survey in cooperation with. titude of waterways in Wisconsin Most bridge crossings the Jefferson County Highway Department began moni. result in a constriction of the natural cross section of the toring bridge scour at the County Highway B bridge over. stream which can lead to increased velocities during the Crawfish River in Jefferson County Wisconsin The. conditions of flooding In some cases the local flow condi purpose of this report is to describe the two monitoring. tions produce extremely high velocities that can scour the approaches used at the three sites fig 1 present selected. sediment in the streambed If the local scour conditions are results and discuss the pros and cons of the different. severe enough to expose the foundation of bridge piers or approaches. abutments the results can be catastrophic, As part of a National Bridge Inventory NBI to docu. ment the condition of the nation s bridges the Wisconsin Methods. Department of Transportation WisDOT has completed an. assessment of the bridges in Wisconsin One of the factors Two different data collection approaches were used at. included in the inventory is the potential for excessive the three sites in part due to funding restrictions This sec. scour in the vicinity of the piers and footings relative to the tion presents a description of the equipment and the data. base of the footing The methods used to assess the scour collection procedures used at each site In addition relative. 2 Bridge Scour Monitoring Methods at Three Sites in Wisconsin. Balsam Road MARATHON,Big Eau Pleine River,Highway 35. Tank Creek,County Highway B,Crawfish River, 0 25 50 Miles Base from Wisconsin Department of Natural.
Resources hydrography and U S Geological,0 35 70 Kilometers Survey 1 24 000 digital data. Figure 1 Location of the three sites with bridge scour monitoring. costs of installation and operation are presented The three the reel to the weight using a series of counters The gages. sites are presented in relation to the degree of sophistica are operated by lowering the weight to the water surface. tion of the equipment used to monitor streambed scour and then to the streambed and the distances from the gage. to each surface are recorded on a field form The gages can. be read to within 0 01 ft 0 3 cm but the accuracy of dis. County Highway B Bridge Crawfish River, tance to the streambed is probably on the order of 0 05 ft. The County Highway B bridge spans the Crawfish 1 5 cm The measurement accuracy will depend upon the. River in Jefferson County The bridge which was rebuilt technique used to drop the weight to the streambed without. in 2002 consists of three spans supported by two piers allowing it to be carried a substantial distance downstream. that rest on spread concrete footings The bridge has an during high flow conditions A 10 lb 4 5 kg downrigger. overall length of 230 ft 70 m The bed material consists ball was selected to minimize this problem Measure. of a 10 foot 3 meter layer of loose gray silt mixed with ments were collected approximately monthly from March. limited clay and sand over a layer of dense brown fine to through May of 2003 and in May and June of 2004 The. coarse sand mixed with some silt The bridge inventory cost of the equipment in 2002 was approximately 3 000. for this site resulted in an NBI Item 113 code of 8 which and the cost of installation and operation for a one year. represents a stable foundation for calculated or estimated period was approximately 3 300. scour conditions, The equipment installed at the site consists of two Balsam Road Bridge Big Eau Pleine River. manual wire weight gages installed on the upstream rail. of the bridge fig 2 in line with the two piers The gages The Balsam Road bridge spans the Big Eau Pleine. contain a calibrated reel which displays the distance from River in Marathon County fig 3 Currently 2005 the. Figure 2 Wire weight gages circled on the County B bridge. over the Crawfish River in Jefferson County Wisconsin. bridge has been removed and a new structure is being. built The old bridge which was built in 1939 consisted of. four spans supported by three piers founded on 30 ft 9 m. timber piles which were driven to the point of refusal The. bridge had an overall length of 220 ft 67 1 m The bed. material consists of a 4 8 foot 1 2 2 4 meter layer of sand. with a varying amount of silt and gravel Bedrock is about Figure 3 Photograph showing the Balsam Road bridge over. 25 ft 7 6 m below the streambed The bridge inventory the Big Eau Pleine River in Marathon County Wisconsin. for this site resulted in an NBI Item 113 code of 3 which. represents an unstable foundation for calculated or esti. mated scour conditions The transducers were initially mounted using a length. The equipment at the site consisted of two Datasonics of channel iron that was strapped to the surface of the 5 ft. PSA 916 sonar transducers mounted on the upstream and 1 5 m diameter corrugated steel pier At the bottom of. downstream edges of the eastern most bridge pier Divers the channel iron the transducers were angled to prevent. from the Marathon County Highway Department found the signal reflection from the footing The upstream mount. footing for this pier exposed above the streambed and the was damaged during ice flows in the spring of 2000 and. evidence of scour was much more pronounced than at the a new mount was installed in November 2000 with the. other piers The transducers were connected to a Camp assistance of the WisDOT and their reach all truck This. bell Scientific CR10 datalogger which recorded distance second mount was damaged during ice flows in the spring. to the streambed at the two locations using a 15 minute of 2002 Because the upstream side of the pier is generally. recording interval The stated accuracy of the sonar units more vulnerable to scour it is necessary to position the. is 0 083 ft 2 5 cm Data from the Campbell datalogger sonar devices in an area susceptible to damage from ice. was transmitted via phone to the office in Middleton and and debris The cost and difficulty of designing fabricat. was made available through the real time data network ing and installing durable mounting systems cannot be. http wi waterdata usgs gov nwis current type scour understated The ideal system would protect the transducer. The equipment was operated from June of 1998 until and cable from debris damage hold the transducer in a. September of 2001 The cost of the equipment in 1997 was rigid position and allow the transducer to be removed for. approximately 4 800 the installation cost was approxi service or repair without undue difficulty or cost. mately 4 200 and the annual cost of operation of the With the deployment of unattended electronic equip. equipment was 4 000 ment periodic check measurements are essential to verify. 4 Bridge Scour Monitoring Methods at Three Sites in Wisconsin. the operation of the equipment Check measurements were a Campbell Scientific CR10 datalogger which recorded. made by a local observer and by personnel from the Town distance to the streambed using a 15 minute recording. ship of Cleveland approximately monthly during 1998 and interval In addition to the sonar transducer a Kellor KPSI. semi annually in 1999 and 2000 USGS personnel made Series 760 SDI 12 0 5 psi depth sensor was used to mea. check measurements quarterly between 1999 and 2001 sure the stream stage using the same recording interval. The recorded depth of the scour hole from the transducer The stated accuracy of the sonar unit is 0 083 ft 2 5 cm. data was within 0 3 ft 9 cm of the field measurement and the stated accuracy of the stage sensing equipment is. data for the period June 1998 through March 2000 Few 0 01 ft 0 3 cm Data from the Campbell datalogger was. check measurements were obtained during actual scour transmitted via phone to the office in Middleton and made. events available immediately through the real time data network. http wi waterdata usgs gov nwis current type scour. Wisconsin Highway 35 Bridge Tank Creek The equipment began operating in April of 2000 and. continues to be active as of this writing September 2005. The Wisconsin Highway 35 bridge spans Tank Creek The cost of the equipment in 1999 was approximately. in Trempealeau County fig 4 The bridge which was 3 400 and the cost for fabrication of the mounting system. built in 1951 consists of 3 spans supported by 2 piers and installation was approximately 6 800 The annual. founded on spread footings The bridge has an overall cost of operation of the equipment was approximately. four spans supported by three piers founded on 30 ft 9 m timber piles which were driven to the point of refusal The bridge had an overall length of 220 ft 67 1 m The bed material consists of a 4 8 foot 1 2 2 4 meter layer of sand with a varying amount of silt and gravel Bedrock is about 25 ft 7 6 m below the streambed The bridge

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