Challenges in Traditional Construction Management

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On civil engineering job sites, discrepancies often arise between contractors and clients regarding the interpretation of drawings and the sharing of the completed project vision, leading to various challenges.

• Construction Errors Due to Differences in Drawing Interpretation:
  When only 2D drawings such as floor plans and cross-sectional views are used, it can be difficult for on-site construction workers to accurately understand the designer's intended final result. Differences in interpretation often lead to construction errors. For example, there may be cases where the rebar positions or the placement of structures are misunderstood, requiring corrections later on.

• Insufficient Communication of Design Changes or Adjustments During Construction:
  Even when changes are made to the design drawings during the construction process, the latest information may not reach all workers on-site, leading to mistakes where work continues based on outdated drawings. Even when new drawings are redistributed or verbal explanations are provided, there is often a time lag in information sharing.

• Difficulty Conveying the Final Design with Paper Drawings or 2D CAD Data:
  For clients, imagining the completed project from drawings or 2D perspective views is not easy. Many clients express concerns such as, "I can’t visualize the final product from the drawings or CGI renders" or "I don’t know how the surrounding environment will change." This often leads to discrepancies between the client’s expectations and the contractor’s understanding before the project is completed.

• Perception Gap Between Clients and Contractors:
  As a result of the issues mentioned above, gaps in understanding can arise between the client and the contractor regarding the final design. This can lead to complaints and requests for rework at the time of handover, such as, "This isn’t what I expected." Even if the client believes they have explained everything thoroughly during meetings, the full understanding may not be achieved by both parties.

Benefits of Visualizing Drawing Information with AR

In response to the above challenges, using AR technology to visualize drawing information on-site brings the following benefits to civil construction management.

Real-time Verification to Prevent Construction Errors

By using AR, you can overlay a 3D model based on the design drawing onto the current construction status in real time. This allows you to immediately verify whether the construction matches the design model on-site, checking for any discrepancies or mistakes. As noted, when the design drawing is overlaid on the construction site through AR for easy comparison, construction defects can be detected early and corrected on the spot, preventing costly rework. For example, by using AR to check the positioning of rebar or piping against the design, any errors can be corrected on the same day, leading to improved quality and a shorter construction timeline.
 

Eliminating the Perception Gap Between Clients and Contractors

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By projecting the completed design onto the construction site using AR, both the client and the contractor can view the same model and discuss it together. Traditionally, there was often a subtle difference between the vision of the client, based on the drawings, and the contractor's understanding of the completed project. However, with AR, for example, by overlaying a 3D model of a bridge or road to be completed on the actual site, the client can intuitively understand the final result. Feedback from clients has indicated that "using AR to display 3D models on-site makes it easier to communicate with designers, contractors, and clients," and it serves as a powerful tool to bridge the perception gap between the client and contractor. In meetings using AR, clients are more likely to provide specific feedback such as "this looks just as I imagined" or "I would like this section to be a bit lower," allowing the contractor to propose adjustments on the spot and quickly resolve any discrepancies in understanding.
 

Instantly Verify Design Changes and Make Quick Decisions

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Even when design changes or additional requests arise during construction, AR allows these changes to be immediately reflected and verified on-site. Adjustments that are difficult to convey through revised drawings or verbal explanations become clear when displayed as a 3D model in front of you. For example, if a client asks, "What would the retaining wall look like if we raised it by 50 cm?" the effect can be instantly visualized in AR on-site, allowing both the client and contractor to evaluate the changes together. This enables on-the-spot decisions and discussions about additional work, significantly accelerating the decision-making process. By allowing all stakeholders to see the same updated vision, any misunderstandings like "I wasn't informed" or "We had a different understanding" can be avoided.
 

Specific Use Cases of AR

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Next, let's explore some concrete examples of how AR can be applied. Imagine how AR can assist in various stages of construction management.
 

Improving Construction Management Accuracy

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AR also contributes to improving the accuracy of surveying and construction management on-site. For example, by overlaying pre-created 3D design data in AR for alignment, staking (positioning) tasks can be performed accurately and efficiently. Traditionally, positioning was done using surveying equipment and batter boards, followed by comparison with drawings for construction. However, with AR, the design model can be accurately placed on the actual terrain, reducing errors in scale and staking.

When combined with high-precision positioning technologies such as RTK-GNSS, AR can overlay virtual models onto the physical site with centimeter-level accuracy, enhancing surveying precision and enabling faster construction. Additionally, AR is effective for checking the as-built conditions during construction. By overlaying the design model onto the completed sections, discrepancies in the final results can be immediately identified, improving the accuracy of quality control.
 

Use of AR in Meetings Between Clients and Contractors

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AR is a powerful tool during meetings between clients and contractors. For example, in pre-construction neighborhood briefings or regular meetings with clients, the contractor can use a tablet to display the completed model of the structure in AR on-site. This allows the client to visualize the final result, which is difficult to convey with words or drawings alone. By viewing the finished image overlaid onto the real site, the client can intuitively understand how the project will look upon completion, providing them with reassurance and confidence.

When communication between stakeholders is facilitated through AR-displayed 3D models, discrepancies such as "This is not what I expected" can be eliminated in advance. Additionally, during meetings, the model can be adjusted or switched to alternative proposals in real-time, allowing for quick revisions to plans based on client feedback. For remote clients, live sharing of AR visuals from the site enables immersive online discussions. In the era of increased remote meetings due to the pandemic, AR allows clients and contractors to discuss the same visual, reducing perception gaps and enhancing communication.
 

Progress Management and Visualization of the Final Design

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With AR technology, even during construction, you can overlay images of completed structures such as bridges onto the actual site. The image shows an example of projecting a model of a bridge to be constructed over a river. By combining the model with the real background, clients can intuitively grasp what the finished structure will look like, making it easier to reach an agreement with the contractor.

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AR is also useful for progress management. The current progress of each construction phase can be visualized on-site, allowing you to compare it with the planned progress. For example, in tunnel construction, overlaying the current excavation area with the design model in AR enables quick verification of whether the excavation has reached the planned line. In road construction, it allows for real-time checks on the roadbed height and slope to ensure they meet the design specifications. Using AR for progress verification enables data-based decision-making, improving the accuracy of schedule management rather than relying on intuition.

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Moreover, AR is effective in presenting the expected final design. Even before completion, the AR model can be displayed on-site to assess its integration with the surrounding landscape, aiding in landscape planning and stakeholder approvals. For example, in bridge or dam construction projects that require consideration of the landscape, showing the expected final result in AR helps to share the design with local residents and authorities, providing them with reassurance. Visualizing the final product makes it easier to gain understanding and cooperation from stakeholders.
 

LRTK

An AR Tool that Requires No Coordinate Alignment and is Easy for Anyone to Use

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Finally, we introduce LRTK, a solution that makes AR use on-site more accessible. LRTK is a tool developed by Lefixea, a startup from the Tokyo Institute of Technology, that uses a compact RTK-GNSS receiver attached to an iPhone or iPad. With this device and app, anyone can easily perform AR displays based on centimeter-level high-precision location data. In other words, it’s a groundbreaking system that transforms an ordinary smartphone into a versatile surveying tool and high-precision AR device.

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The biggest feature of LRTK is that no on-site coordinate alignment is required. Traditional AR apps typically require manual alignment of the 3D model to a reference point on-site, or setting up markers for recognition. This often leads to positional drift as users move. However, with LRTK, the position of the model is continuously tracked using accurate RTK-GNSS data, ensuring it always aligns with the actual coordinates without any drift.

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No initial calibration is necessary—simply turn on the device, and the design model is immediately projected onto the site using the global coordinate system. For example, in traditional methods, the model needed to be aligned with local reference points, but with LRTK, this process is automated using GNSS, allowing precise model placement even in locations where visibility is difficult due to vegetation or structures. This drift-free AR projection is made possible through a simple workflow that anyone on-site can handle, and it’s a unique advantage that only LRTK offers.

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Furthermore, LRTK features immediate cloud-based sharing of positioning data, photos, and point-cloud data, enabling seamless data collaboration between the site and the office. This enhances the speed of sharing surveying results and reporting on as-built inspections, driving overall efficiency in construction management. By utilizing LRTK, which combines high-precision positioning and AR display, digital transformation (DX) in civil engineering sites can be rapidly accelerated, from sharing the final design image with the client to preventing errors and managing project progress.

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Currently, we are accepting free requests for LRTK-related materials. If you’re interested in introducing AR technology to your site, please don’t hesitate to request detailed information about LRTK. LRTK is the only tool that requires no on-site coordinate alignment and can be easily used by anyone. Don’t miss the opportunity to dramatically improve the precision of construction management and communication with cutting-edge AR technology!