National Academies Press: OpenBook

Portable Scour Monitoring Equipment (2004)

Chapter: Chapter 4 - Conclusions and Suggested Research

« Previous: Chapter 3 - Interpretation, Appraisal, and Applications
Page 48
Suggested Citation:"Chapter 4 - Conclusions and Suggested Research." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
×
Page 48
Page 49
Suggested Citation:"Chapter 4 - Conclusions and Suggested Research." National Academies of Sciences, Engineering, and Medicine. 2004. Portable Scour Monitoring Equipment. Washington, DC: The National Academies Press. doi: 10.17226/13719.
×
Page 49

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

48 CHAPTER 4 CONCLUSIONS AND SUGGESTED RESEARCH CONCLUSIONS This research resulted in improved deployment, position- ing, and data collection procedures for portable scour monitor- ing work. These improvements will facilitate data collection under adverse conditions and will allow more successful mon- itoring at a wide range of bridges under flood flow conditions. The research was conducted recognizing the need to provide solutions that are easily used and affordable by state and local bridge owners. The research completed did not include work directed toward new measurement technology, but concentrated on improved deployment methods. The proposed solution, as developed in the articulated arm truck, did not meet all the identified criteria defined for this research. In particular, the research did not solve the measurement problems with debris and ice. However, the research did solve some difficult imple- mentation problems and provided improvement over current practice in flood flow monitoring. The resulting product will be beneficial to bridge inspectors and should greatly improve their ability to get reasonable results under adverse conditions. SUGGESTIONS FOR FURTHER RESEARCH Although this research produced a reliable, fully functional articulated arm device, improvements could be made to the device, and other areas of research and development would further improve the ability to make flood flow measurements. Physical Probing Attachment A physical probe was fabricated from Schedule 80 stainless steel pipe that could be used for point measurements of scour hole conditions. Knowing the location of the end of the crane, these point measurements could be completed with accurate positioning. The primary limitation of the probe was that it could be used only in gravel/cobble beds or around piers with riprap, because the strength of the crane hydraulics would drive the probe into the bed in softer materials. Given this con- cern, a sensor at the end of the physical probe would be bene- ficial to help identify the water sediment interface. Such a sensor might be as simple as a pressure switch; however, alter- native solutions that do not require wires or cables would be preferable. Rigid Frame Deployment of a Kneeboard Further research and development on the kneeboard con- cept deployed on a rigid frame would be valuable. As devel- oped, the kneeboard on a rigid frame was able to facilitate data collection on bridges with projecting decks and/or large overhangs. However, there were deployment issues related to getting the kneeboard on the water surface and maintain- ing a stable platform for measurement. The conclusion was that a rigid frame deployment of a kneeboard was viable, but an alternative floating platform might work better. A kneeboard works well on a tether, and the larger surface area is necessary under those conditions to keep the board upright. However, on a rigid frame it is not necessary to have as much flotation, and a different board or floating system might work better. One idea is a pontoon-style system with a stabilizing fin between the pontoons that locates the trans- ducer under water 6 to 12 inches and also provides direc- tional stability. Alternatively, the transducer could simply be mounted on a rigid, horizontal frame submerged under water without flotation. Angular Measurement of Rotator The rotator at the end of the crane was included to provide the ability to rotate a sensor deployed at the end of the crane. The angle of rotation was measured with a 10-turn poten- tiometer. Mounting this sensor on the rotator required sig- nificant fabrication, and the 10-turn potentiometer was not as robust or durable as the other sensors included to monitor crane position. An improved sensor arrangement for measuring the posi- tion of the rotator would be desirable if the concept of a knee- board on a rigid frame is pursued further. The rigid frame deployment of the kneeboard was ultimately the only appli- cation that required rotational ability. For example, rotational ability was not necessary for the streamlined probe concept, after it was modified to allow it to rotate and track the cur- rent on its own. It was also not necessary for any of the cable-

49 However, this work concentrated on direct sonar measurement with the streamlined probe and the kneeboard deployment on a rigid framework. These programs were fully developed and field-tested and are believed to be fairly robust software packages. The cable-suspended program and the physical probing did not receive the same level of development and testing. They were developed to a prototype level, but did not receive the same degree of field testing as the other programs. Devel- oping fully functional software that is thoroughly de-bugged is a time-consuming process that requires extensive testing. Additional testing and development of these two pieces of software would provide greater confidence in their operation and use. Remote Control Boat The use of an unmanned, remote control boat offers several advantages for flood monitoring, including safety, access issues, measurement anywhere around or under the bridge, and the ability to work at both low- and high-clearance bridges. Previous research has been completed on the use of remote control boats for scour and stream gaging work, involving the use of both gas and electric propulsion systems. Ultimately, the hull and the propulsion system should be designed around the payload that must be carried, and, using the wireless sonar developed as part of this project, the payload requirements would be relatively small. Other areas of concern include devel- oping a boat durable enough to survive the potential rough water, debris, and difficult operational conditions. This would require ruggedized servos and controllers mounted in water- proof compartments. The use of an unmanned remote control boat for scour mon- itoring was identified during the literature review in Phase I. Although this concept was not pursued as part of this research project, it is still a viable concept that should be investigated further. suspended operations. The tilt ability at the end of the crane (as provided with the additional hydraulics that were added to the crane) was a desirable and necessary improvement. How- ever, the additional capability to rotate and to measure that rotation added significant cost and complexity to the crane. Therefore, without additional research and development to make the kneeboard concept more functional, the crane design and construction could be simplified by eliminating the rota- tor and its measurement. Alternative Positioning Systems The calculation of the location of the end of the crane was based on assorted tilt and displacement sensors, along with a surveyor’s wheel to locate the truck on the bridge deck. This system worked well. With the exception of the rotator mea- surement, as discussed above, the sensors selected were fairly simple and robust. The computer software was designed to complete all the geometric calculations necessary to define crane location, without any direct operator involvement. However, this approach did create a system of multiple components that required a certain electronic aptitude to oper- ate and maintain. A simpler positioning system involving fewer components, such as the low-cost GPS concept explored dur- ing the research, might be preferable if the required accuracy was possible. Therefore, as GPS technology continues to im- prove, an alternate positioning system based on GPS might be possible. Another approach could involve proximity sensors located on the bridge a fixed distance ahead and behind the truck to track the movement of the crane arm. Additional re- search might identify other methods as well, with the intent being to reduce the number of sensors and calculations neces- sary to track the movement of the crane arm. Additional Software Development Extensive effort was put into creating a software package to automate the data collection process with the articulated arm.

Next: References »
Portable Scour Monitoring Equipment Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

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.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!