| Title |
PORTABLE INSTRUMENTATION FOR REAL-TIME MEASUREMENT OF SCOUR AT BRIDGES
|
| Accession No |
00804724 |
| Authors |
Mueller, D S; Landers, M N |
| Period Covered |
9101-9812 |
Corp. Authors
/ Publisher |
U.S. Geological Survey  ; Federal Highway Administration
|
| Publication Date |
20001200 |
| Description |
87 p.;
Figures; Photos; References(34); Tables(1) |
| Languages |
English
|
| Abstract |
Portable scour-measuring systems were developed to meet the requirements of three different applications: bridge inspections, limited-detail data collection, and detailed data collection. A portable scour-measuring system consists of four components: (a) the instrument(s) for making the measurement, (2) a system for deploying the instrument(s), (3) a method to identify and record the horizontal position of the data collected, and (4) a data-storage device. Commercially available instruments were evaluated for use in measuring scour at bridges during floods. The systems developed consist primarily of commercially available instruments, which were modified and interfaced to achieve the required functionality. The bridge-inspection system is intended for use by bridge inspectors to measure the streambed elevation around piers and abutments to ensure the stability of bridge foundations. The system developed and described here uses a low-cost echo sounder to measure the water depth and a tethered float to deploy the transducer around the bridge piers and abutments. Data are recorded on a chart-recording echo sounder or in a notebook if the echo sounder has only a graphical or numerical display. The U.S. Geological Survey has been collecting limited-detail data on scour at bridges for several years. The only additional development for limited-detail data collection was to use a float to deploy the transducer of an echo sounder, which allows data to be collected beneath the bridge and along the sides of the piers. The detailed data collection system allows collection of detailed channel bathymetry and hydraulic data at the bridge and in the approach and exit reaches. Channel geometry is measured using a digital echo sounder; three-dimensional velocity profiles are collected using a broadband acoustic Doppler current profiler (BB-ADCP); and the position of the data collected is measured using either a range-azimuth positioning system or a differential global positioning system. All data are transmitted to shore where they are stored on a field computer. Because of the spatial coverage required of detailed data, the instruments must be deployed from a boat. Although manned boats are frequently used on some streams, safety and access considerations, particularly on small streams, led to the development of a remote-control boat. The remote-control boat consists of a flat-bottom jon boat powered by an outboard engine with servos and switches mounted directly on the engine to allow control of the engine by use of standard recreational remote controls. All systems developed have been used successfully during major floods and allow data to be collected more efficiently and in more detail than was previously possible. |
| TRT Terms |
Bathymetry ; Bridges ; Data collection ; Floods ; Hydraulics ; Measuring instruments ; Portable equipment ; Real time information ; Scour |
| Other Terms |
Acoustic Doppler current profiler; Echo sounding; Remote-control boat |
| Subject Areas |
H22 HYDROLOGY AND HYDRAULICS; H25 STRUCTURES DESIGN AND PERFORMANCE; I24 Design of Bridges and Retaining Walls |
| Contract Number |
DTFH61-91-Y-30036 |
| Report Number |
FHWA-RD-99-085,; Final Report |
| Availability |
National Technical Information Service Order Number: PB2001-102040
|
| URLs |
|
| TRIS Files |
HRIS; NTL |
| Database |
TRIS Online |
TRT
