Manual monitoring, sometimes referred to as campaign-based monitoring, requires a surveyor to take repetitive measurements of the same monitoring points. This data is typically collected using total stations due to the high accuracy nature of monitoring data. Additionally, collected data needs to be managed in an efficient manner. Oftentimes this is done through complex spreadsheets and CSV files. This article takes a look at the needs for manual monitoring and how to improve the manual monitoring workflow by automating certain tasks.

Applications for Manual Monitoring

There are many applications that benefit and require manual monitoring. Deciding on the manual monitoring setup and scheme is defined by the 1) project size, 2) duration of the project, 3) how often measurements are required, and 4) accuracy required to determine movement. 

For project size, small-size projects such as monitoring pile installations or deep excavations are best served by a single total station on site during the entire construction process. When installing piles near critical infrastructure, the contractor needs to ensure the construction activities do not affect these. Surveyors can accurately measure movements of the construction process to the millimeter level using a total station while on-site.

Image 1. Short-term construction, i.e., pile installation, deep excavations and shoring.

short-term construction

Repeated measurements are required to generate sufficient redundancy for accurate monitoring statistics. This requires repetitive and tedious operations by the surveyor. Additionally, it is recommended to make measurements as fast as possible to reduce errors introduced by environmental factors such as pressure, humidity, and temperature changes.  When establishing network control or checking an existing network for movement, these repeated measurements and environmental factors are made to meet strict accuracy requirements.

 Image 2. Survey network control and verification.

control and verify

When using total stations to collect monitoring data, a line of sight is necessary to ensure repeatability of measurements. This means careful planning and precise placement of instrument and target positions.

Some movements cannot be detected over short periods of time, requiring repeated visits to the site over long periods of time to determine trends. Structures such as dams can exhibit small amounts of movement over the course of months or years and seasonal changes. Survey crews often time monitoring these behaviors once per season/year to capture this movement, providing dam operators with data for informed decision making. 

Image 3. Long-term subsidence and trends, i.e., low-risk slopes, seasonal movement of dams.

long-term subsidence

Monitoring with Trimble Access and TBC

Having a system that fits into your monitoring workflow is necessary to ensure projects can be performed efficiently, and data delivered to the client, in a meaningful way. The Trimble Manual Monitoring system includes three parts:

  1. Trimble® Access™ Monitoring field software and a robotic total station to collect data and schedule monitoring measurements in the field
  2. Trimble Sync Manager to simplify the exchange of survey data between the field and office
  3. Trimble Business Center™ (TBC) Monitoring office software to manage, process, and generate quality reports on displacements for client requirements

monitoring system

Automating Round Collection and Scheduling in Trimble Access

Collecting data for monitoring projects involves repetitive measurements of the same points. These repeated measurements, when performed manually, can increase operator errors and time on site collecting data. Trimble Access Monitoring automates these measurements, drastically reducing time on site. For projects requiring real-time results such as monitoring pile placement, displacements are shown automatically after the measurement is made with warnings issued if exceeding tolerances. Once finished on site, the data can be transferred immediately to the office using Trimble Sync Manager.

Benefits

  • Automated round measurements and scheduling removing operator errors and reducing field collection time
  • Station and target transfer between jobs ensuring that no data is lost between each monitoring campaign
  • Real-time displacements and residual alarms providing the operator with notification of significant movement 
  • In-field movement charts and scatterplots for fast and simple analysis while on site

Workflow in Trimble Access Monitoring
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Comprehensive Analysis and Reporting in TBC

After data has been collected, TBC manages, processes, and reports on movement data. First, a network adjustment is performed to solidify the control network that will be used for subsequent monitoring campaigns. Once the monitoring data is collected, 3D displacement vectors visualize movement patterns on site. This helps determine specific trends on-site such as subsidence, twist, or tilt. Additionally, thresholds can be set to notify users when movement surpasses alarming conditions. Finally, comprehensive charts and reports can be created for clients and stakeholders covering all movement data for the project.

Benefits

  • Manage and create monitoring deliverables from all survey data in one platform including GNSS, total station, and level 
  • Perform rigorous network adjustment using fixed, free, and other adjustment types to ensure site control points are established with confidence
  • Set warning and alarm thresholds to signify when any movement has occurred
  • Visualize movement patterns in 3D to determine trends on-site such as subsidence and rotation.
  • Create comprehensive monitoring reports showing displacement information across the site for all epochs

Workflow in TBC Monitoring

tbc 1tbc 2

Improve your monitoring game by automating your workflow using Trimble Access and TBC. For more information, view this webinar recording and YouTube video, or contact the Trimble Monitoring team here.


About the Author

Jodie Craig

Jodie is on the Trimble Geospatial Marketing team, based in Westminster, CO, USA.