TEPSCO Develops Precast Foundation for Special High-Voltage
Transmission Towers to Improve Productivity at Construction Sites
February 22,2023
Tokyo Electric Power Services Co., Ltd.

Tokyo Electric Power Services Co., Ltd. (Headquarters: Koto-ku, Tokyo; President: Yasuhiro
Kubo) has developed a precast cap for the mono-pile foundation that supports special highvoltage transmission towers (hereafter “transmission towers”) and this product is now available
for purchase. We believe that this development will help to reduce the number of specialized
workers required for the construction of pile foundation slabs. Even less skilled and lessexperienced workers will be able to install tower leg components with a high degree of precision,
thus significantly reducing the time needed for installation.

1. Development Background
In Japan, approximately 1,000 transmission towers are built each year to support electricity
transmission lines.
(Reference: https://www.occto.or.jp/iinkai/kouikikeitouseibi/2016/files/seibi_18_01_02.pdf)

7According to the “Basic Policy for Realization of
GX: Roadmap for the Next 10 Years” approved by
the Cabinet on February 10, the national grid will be
developed on a scale more than eight times that ofthe past 10 years. However, the power transmission
construction industry is currently facing a lack ofconstruction capacity and there is an urgent need toBase plate

improve productivity through mechanization andother means.
Figure 1: Pile and pile foundation slab

The transmission tower is supported by 4 legs on independent footing (Figure 1). The slab of
the pile foundation is constructed according to the procedure shown in Figure 2.

1

Installing leg
components

Installation ofreinforcing bars

Assembling
formwork

Pouring concrete

Figure 2: Construction Procedure of Pile Foundation SlabThe construction of a transmission tower foundation requires the expertise of a powertransmission worker who possesses extensive experience and skills in following the procedures
outlined in Figure 2. This step is particularly challenging because leg components must be installed
to ensure that the height, position, angle, and direction of the tower are within permissible values,in order to prevent interference with the tower assembly after the foundation has been constructed.
This process demands skilled power transmission engineers.
However, as in other industries, the aging population and the difficulty in filling positions withyounger workers have led to a severe shortage of specialized workers needed for constructing
transmission lines. To address this issue, the Ministry of Land, Infrastructure, Transport, andTourism has been promoting “i-Construction”* as a solution to the shortage of human resourcesin bridge and other construction sites. They have also identified the introduction of total
optimization (standardization of concrete work standards, etc.) as one of the three main pillars(issues) for the construction industry to prioritize.
To promote i-Construction at transmission line construction sites, we have developed a precast
foundation for constructing the slab of transmission towers that is manufactured in a factory andthen assembled on-site, eliminating the need to order customized foundations for each site. Thisapproach has resulted in a significant reduction of on-site work and improved productivity, while
also addressing the shortage of specialized workers by standardizing work processes.
*The i-Construction initiative is led by the Ministry of Land, Infrastructure, Transport, and Tourism (MLIT), with the goal of enhancing
productivity at construction sites across the entire project process, including surveying, design, construction, inspection, and maintenance.

2. Outline of Precast Foundation Development
Figure 3 provides a comparison between the installation procedures of conventional pilefoundations and the newly developed precast method. With the new approach, the pile foundation
components (cap) are pre-manufactured in the factory as precast components (Fig. 4), and thenassembled on-site. Specifically, the inner precast components are installed at the pile head,followed by the outer precast components in the order of 1 and 2. Finally, concrete is poured into
the gaps between the inner and outer components to complete the construction of the pilefoundation slab.

2

Installing leg
components

Assemblingformwork

Installation ofreinforcing bars

Inner PC setup

Outer PC1 setup

Outer PC2 setup

Inner precast with leg
components (inner PC)

Pouring concrete

Pour concretein gaps
Pouring in liquid
concrete

Outer precast 2(Outer PC2)

Outer precast 1(Outer PC1)

Figure 3: Usage of Precast Components (Comparison with Old Method)3

Figure 4: Examples of Precast Components

Based on our test results, the accuracy of this method is well within the acceptable range forstandard power line construction. Additionally, the number of man-hours required for installation
can be reduced from 14 using conventional methods to 6, which is approximately a 60%
reduction. By producing accurate precast components at a factory, it is a matter of simply
assembling them on-site, eliminating the need for permanent on-site professionals to makedelicate adjustments, and enabling inexperienced workers to build foundations on par withexperienced ones. Furthermore, the reduction in on-site work will minimize the need forequipment to deal with site location and seasonal effects (such as high temperatures andsnowfall), resulting in reduced transportation costs.
This method was employed at a TEPCO Power Grid, Inc. site in the Tsurumi Ward ofYokohama City, Kanagawa Prefecture, late last year, and other power companies are seriously
considering introducing it. We plan to extend our sales activities to other industries that
handle steel towers, thus supporting the construction industry in saving labor and resolving
4the shortage of human resources by implementing this method.

Figure 5: Photos of Precast Foundation on Construction Site5

《Inquiries》
For inquiries regarding the contents of this press release or sales, please contact us at the following
number or email address:〇Tokyo Electric Power Services Co., Ltd.
PR Department: Hasegawa and Tanaka
TEL︓03-6372-5942
E-Mail︓ msr-tanaka@tepsco.co.jp

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