Discover the significance of precise positioning estimates and how real-time kinematic (RTK) positioning uses a network of fixed base stations at known coordinates to ensure accurate receiver location verification.
Construction surveyors face numerous challenges in preparing a site, considering both visible and hidden factors. From topography to property lines, accurate measurements are crucial for every aspect of site preparation.
Among these challenges, accurately locating underground utility lines is perhaps the most difficult. These vital systems, buried beneath the ground, carry electricity, water, natural gas, sewage, and internet, providing essential services. A misstep during excavation can lead to expensive or even life-threatening consequences, making precise location estimates a critical task.
While there are various tools available to detect underground utilities, not all are suitable for high-precision applications. This article highlights the significance of precise positioning and explores the advantages of real-time kinematic (RTK) positioning as the most reliable solution.
The Importance of Accurate Utility Line Location
Accidents involving underground utilities are more common than many realize and can result in significant disruptions to vital services, such as electricity and water. According to the Common Ground Alliance (CGA), accidental utility strikes cost the U.S. over $30 billion annually. These incidents often cause more than financial loss, with some resulting in injuries or fatalities.
The CGA’s 2022 DIRT Report indicated that over 25% of utility strikes were due to locator errors. Furthermore, for the first time, construction workers and excavators were the leading cause of reported damages. These findings underscore the critical need for surveyors to accurately identify the locations of underground utilities.
Essential Steps for Safely Identifying Underground Utilities
Before any excavation work begins, construction teams must follow these key steps:
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Call 811: Each state has an 811 service that must be contacted before digging. Utility companies will respond by marking known locations with flags or paint.
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Confirm utility responses: Excavation should not start until all utility companies have responded and marked the relevant lines.
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Obtain utility maps: If available, surveyors should gather utility maps to help guide the location verification process. These may come from local authorities, utility providers, or private landowners, but should not be relied upon solely.
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Select the right verification method: Surveyors should assess whether the utility lines are conductive or non-conductive and consider the depth and interference level before choosing the best verification tool.
Methods for Locating Underground Utility Lines
Several non-invasive techniques are used to locate underground utilities, including:
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Ground Penetrating Radar (GPR): GPR uses radar pulses to detect underground pipes. It can identify both conductive and non-conductive materials, but it is costly and requires skilled operators.
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Electromagnetic Conductivity: This method detects conductive materials by generating electromagnetic fields. However, it only works with conductive pipes and can experience interference from nearby materials.
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Acoustic Method: Sound waves are sent underground, and the return waves are analyzed to locate pipes. This method works well in various soil types and can reach depths of up to 30 feet, though noisy environments may disrupt results.
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Radio Frequency: Similar to electromagnetic conductivity, this method uses radio signals to detect conductive pipes. It may also face interference from nearby conductive objects.
RTK Technology for Enhanced Accuracy
RTK technology enhances the accuracy of utility location tools by utilizing a network of fixed base stations with known positions. By reducing potential errors between the base station and the surveyor’s device, RTK ensures location accuracy within 2 to 4 centimeters.
RTK technology also simplifies the process of locating and mapping utilities. Traditional methods involve two separate teams—one to locate the utilities and another to map them. With RTK-enabled equipment, surveyors can accomplish both tasks simultaneously, improving efficiency and accuracy. For instance, RTK-enabled electromagnetic locators combine location detection with mapping, instantly translating underground data into digital maps within a mobile app.
Reliable Tools for Precise Utility Location
When breaking ground on a new project, it’s vital for construction firms to be certain they are excavating in the correct location. Incorrectly digging near underground utilities can have disastrous consequences.
By utilizing RTK technology alongside other scanning tools, surveyors can produce accurate maps of underground utilities, minimizing the risk of accidental damage and ensuring the safety of the project.
