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33 Conclusions This study documents and synthesizes the state of practice for implementation and use of advancements in unstable slope instrumentation and monitoring by DOTs over approximately the last decade. The instrumentation and monitoring technologies evaluated in the synthesis include in situ instrumentation, remote sensing, warning systems, and data management, including acquisition, storage, transmission, presentation, and visualization. The study is based on â¢ A review of domestic and international literature to identify emerging technology that could inform DOT practice improvements; â¢ A survey of geoprofessionals at state DOTs to better establish the current state of practice and barriers to implementation of existing and new technology; and â¢ Follow-up interviews with selected agencies that more fully illustrate the range of current practice and recent practice innovation. Unstable slopes impact almost every state DOT. When unstable slopes are selected for instrumentation and monitoring, the reasons are most often based on the judgment of DOT staff and in reaction to an event. The data from instrumentation and monitoring systems are used by a majority of the DOTs for â¢ Tracking movement of unstable slopes to support treatment decisions; â¢ Improving the reliability of design decisions; â¢ Supporting maintenance and operations decisions; and â¢ Verifying slope performance is within specifications. More than a third of the DOTs also rely on instrumentation and monitoring data to inform warning or emergency action work on unstable slopes. Remote sensing is the technology showing the greatest increase of new use by DOTs to monitor unstable slopes within the last 10 years. A similar conclusion is apparent in the literature as well, with increased application of remote-sensing methods to unstable slope problems internationally and across infrastructure types. The literature review suggests that the pace of advancement in remote-sensing technology is more rapid than in other instrumentation and monitoring technology. Of the remote-sensing technologies used by DOTs, ground-based and aerial LiDAR and photogrammetry are the methods showing the greatest increase of new use, meaning, within the last decade, these methods are being applied for the first time in many DOTs. Ground-based, in situ geotechnical instruments also show increased use in DOTs within the last decade, with the largest adoption gains for in-place inclinometers, tilt meters, borehole extensometer/deformation instrumentation, and groundwater and surface water systems. However, for each of these systems, a portion of the respondents indicated that these systems C H A P T E R 5
34 Advances in Unstable Slope Instrumentation and Monitoring have been used for over a decade in their agency. This suggests that, while ground-based in situ instrument use is increasing in DOTs, the increase is occurring primarily through the greater adoption of existing instrumentation technology that has been available for over 10 years. The practices for data collection, viewing, and communication of instrumentation and monitoring data have relied heavily on manual and paper-based methods. Within the last decade, the frequency of use of electronic-based methods has increased for DOTs through use of technology such as remote viewing of near-real-time and recorded data, web-based access or presentation of data, onsite data acquisition, and transmission of data offsite via wireless (radio, cellular, etc.) telemetry. Approximately 25 to 50% of the responding DOTs reported adopting these data management and communication technologies within the last decade. For nearly all responding DOTs, the management of instrumentation and monitoring data is site-specific and often a function of the technologies used on site. Most of the states use the data from instrumentation and monitoring programs in reporting or action planning on monthly to seasonal bases. Approximately a third of the DOTs are using web-based platforms to access data from site-specific systems, and about 20% of the DOTs indicated having a program-wide web-based system for viewing and managing multiple sites from one web location. For funding instrumentation and monitoring projects, DOTs use a combination of several sources, with the majority originating from emergency/contingency pool sources, operations and maintenance budgets, construction funds, and pre-engineering or design budgets. The most common range in annual spending reported by DOTs on instrumentation and monitoring is $10,000 to $50,000, with 10 states indicating spending less than $10,000 and 2 states indicating spending greater than $250,000 per year. The variation appears to be related to factors beyond program size because in some cases smaller programs are spending more than larger programs. The survey results suggest that installing and maintaining instrumentation and monitoring equipment is more likely to be performed by DOT staff, while work involving warning systems and remote sensing will be completed by contractors/consultants. Regarding the size of the instrumentation and monitoring programs in DOTs, only 19% of the respondents indicated the programs were the right size. Most states (greater than 60%) indicated that training, additional staff resources, and additional funds would enable a greater use of instrumentation and monitoring technology in their DOT. The suggested research needs developed from the synthesis outcomes include developing frameworks to match the application of technology to the problem of unstable slopes, cost and benefit guidance to support business case decisions, and training and tools that can be used by practitioners for implementation of specific instrumentation and monitoring technologies. Further discussion describing the research suggestions is provided in the following paragraphs. Case study and survey comments indicated knowledge of the benefits of instrumentation and monitoring systems would be valuable for understanding what the technologies can do to support actions regarding operational management of unstable slopes. Key to this research need would be practical guidance for DOTs in the review and selection of specific technologies and criteria for cost-benefit analysis. Within this guidance would be information on the wide range of technologies; how the different technologies are used to monitor slopes based on material types, modes of failure, and established and new applications; and data collection, data transmission, and data management considerations. Once there is knowledge of the capabilities of instrumentation and monitoring technologies, research could be undertaken to provide guidance to assist structured trade-off decision making. The development of guidelines to help practitioners determine when the data from instrumentation and monitoring technologies would be useful.