Innovating as-built verification

Author: Yoshie Katagiri

In 2018, the Japanese Ministry of Land, Infrastructure and Transport (MLIT) publicly invited bids for a ‘Project to Introduce and Utilise Innovative Technology to Dramatically Improve Productivity on Construction Sites’ under its i-Construction initiative aiming to boost productivity on construction sites as part of a wider innovation strategy. Kanatsu Giken formed a consortium of four companies with Fukui Computer Co., Ltd., Leica Geosystems Co., Ltd., and Sanyo Sokki Co., Ltd., and tendered for the project. The consortium was selected in the category of ‘Techniques Using Data to Improve the Productivity of Construction in Civil Engineering Work.’

四公司联盟的目的是在混凝土结构（例如桥梁基台和码头）上进行3D激光扫描，并使用获得的点云数据进行实行验证，以显着提高施工地点的生产率。此外，他们使用捕获的点云数据与3D设计数据（CIM）的坐标值之间的差异进行了试验并提出了一种新的进度管理方法。

Kanatsu Giken used Leica Geosystems’Leica Nova MS60 MultiStation，一种具有3D激光扫描的仪器，并具有常规总站的测量功能。

“Current as-built verification method is time-consuming and labour intensive because much of the measurement and analysis of disparities is done manually. The reason we bought the Nova MS60 in the first place, was to make these tasks less labour intensive. Soon after the purchase, we found out about the MLIT project. We focused the expertise available across the four companies and came up with a specific method for construction management using points and surfaces. This also had the potential to enable high productivity when verifying the as-built, so we tendered for the project,”describes Yoshinobu Kimura, team leader of the information technology group in the civil engineering division at Kanatsu Giken.

该财团在五个地点进行了现场测量和数据分析，并根据结果进行了编译并提交了MLIT的建议。2019年，MLIT宣布了对所有提交项目的评估 - 该财团获得了“ A”评级，是最高评估。

Comparison between point cloud data obtained by measuring the as-built of cast-in-place piles and 3D design data (blue lines)

平面(粗糙度)点的比较评价cloud data obtained by measuring the as-built of cast-in-place piles against 3D design data

Comparison between point cloud data obtained by measuring the as-built of footing and design data (blue lines)

平面（粗糙度）通过测量与3D设计数据的基础建造获得的点云数据的比较评估

By conventional techniques, it takes a total of three people - a pair taking measurements and a photographer - to measure the as-built of the cast-in-place pile.

使用试用技术，一个人可以操作NOVA MS60进行测量和摄影.The trial techniques reduced the number of man-hours required for measurements of cast-in-place piles by more than half.

基础是具有减震功能的钢筋混凝土基础。倒角时，读取准确的角点可能是一个问题。

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测量工作减半

In the case of piers, due to the requirement to take measurements at height and in confined spaces, planar evaluations using 3D point cloud data is very useful.

The trial was run for the as-built measurement and verification during the construction works on two bridge abutments and two bridge piers of the outer and lower portions of the Ohguni Viaduct in Japan. The results from the trial were divided into cast-in-place piles, footings, and housings.

To be able to efficiently conduct accurate as-built verification of the entire top of the pile was one of the great advantages of the trial technology.

“With the conventional method, when we measured the standard height of the top of the pile, we used a stepladder or something similar to climb over the reinforcements that protrude from the pile and had a surveyor stand in the centre. The pile diameters were measured by teams of two, taking measurements in two directions - one along the axis of the bridge, and the other, perpendicular to this. This work was repeated again and again until all the piles were measured. Another worker was needed to take photos of the as-built verification process.

With the Nova MS60, you can measure from outside the steel reinforcements. It’s no longer necessary for surveyors to work in pairs to measure the pile cores and pile diameters with tape measures and then calculate the central points, as these can be accurately determined later by data analysis,”Kimura解释。

The MultiStation reduced the manhours required for the measurement work to less than half. Worker downtime got reduced from 83.3 manhours with the conventional techniques to 37.27 hours.

In addition, because the data captured by the Nova MS60 is uploaded to the point cloud processing system for the as-built measurements, there is no need to take photos for as-built verification separately. This also eliminated the time involved in organising the photos after the work on site.

The footing is a foundation of reinforced concrete placed on top of the cast-in-place piles. In the trial, the scaffolding proved to be an obstacle. The piers sit on the footing and support the bridging superstructure.

For the piers and footing, scaffolding proved to be an obstacle and the instruments had to be moved frequently. In spite of this, the trial task took 8.5 manhours compared with the 11 manhours for the footing and 30.9 manhours compared with the 40 manhours taken with conventional techniques.

Comparison of point cloud data obtained by measuring the finished shape of the pier and the design data (blue line)

平面(粗糙度)点的比较评价cloud data obtained by measuring the as-built of a pier against the 3D design data

“对于基础和码头，我们只管理了约20％的货运量。但是，如果有许多结构要测量，即使20％也代表了一个大量节省。同样，如果建立3D激光扫描作为标准过程，则建筑工地将设计工作流以建造和去除脚手架，以便可以有效地进行测量，这应该会进一步减少ManUrs，”木村说。

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Use of point cloud data boosts productivity increases accuracy and improves safety

This innovative method of as-built verification using point cloud data has a myriad of potential benefits, including higher productivity, higher accuracy, and improved safety. Furthermore:

• As-built measurement can be performed by a single worker.

• Once the data has been captured, it is possible to measure dimensions between arbitrary coordinates or view cross sections at any position.

• It is no longer necessary to take and organise as-built verification photos.

•能够计算XYZ轴偏差是前所未有的，并且有可能提高维护和管理的精度。

即使在建设进行了进展，桩和基础也被埋葬在地下和看不见之后，这些无形结构的状态也可以在将来准确地测量和精心管理。保持施工过程的详细记录可提高安全性和可靠性，并有望减少重大事故的发生率。

Moreover, the opportunities for application are likely to expand. Potential uses include uploading the captured data to CIM for processing and combining of the above techniques with VR (virtual reality), AR (augmented reality) and MR (mixed reality) technology, and wearable terminals, changing the nature of construction work.

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Immediately view 3D design data superimposed on point cloud data

Merged as-built point cloud data of the entire structure with 3D design data (CIM).

The ease of use, a familiar operating interface of a total station combined with a high-performance motor drive for high-speed rotation and inversion, and a high laser scanning speed resulted in complete user satisfaction.

“ Nova MS60的最大好处是，您可以实时查看在点云数据上叠加在点云数据上的3D设计数据 - 您只需查看Nova MS60现场的屏幕，然后立即查看差异即可。如果读数不在标准值范围内，则测量位置或其他问题是错误的。因此，通过在工作时检查3D设计数据，您可以验证未造成的算法，没有错误，”Kimura解释。

Kanatsu Giken conducted this trial project with the theme to ‘Make the most of technology in the field’ and brought together engineers and the construction site in pursuit of innovation.

“In this trial, we simply put a proposal into practice, showing that there is an alternative way to do things. As the requirements change due to the shift from engagement to full adoption of i-Construction, we will continue to embrace flexible thinking and creativity to improve productivity on construction sites and make the sites a more attractive place to work,”总结是基穆拉。