5,000 People in 6 Days: 130 Metre Relocation of Shibuya Underground Station in Tokyo Subim Major Refurbishment Project

Established in 1946, Tokyo Kyukyu Electric Railway Company (Tokyu) is one of Japan's largest construction companies, specialising in large-scale infrastructure and large-scale commercial construction projects.
In this article, Tokyu shares a workflow on how to apply BIM technology with SketchUp on the Tokyo Metro Ginza Line Shibuya Station construction project.

Tokyo Metro Ginza Line Shibuya Station is located in the centre of Shibuya, a popular area in Tokyo. As an important metropolitan underground line alongside the Hanzomon and Fukutoshin lines, approximately 220,000 people travel on the line every day, and the line passes through a building with the station located inside.

Since its opening in 1938, it has been difficult to carry out large-scale reconstruction. Currently, the station has the following problems: 1. it is not wheelchair accessible; 2. the platform is narrow; and 3. there are no toilets in the station.

Shibuya Station is planned to be reconstructed out of consideration for congestion, safety, and service. Shibuya Station on the new Ginza Line opened on 3 January 2020, making it barrier-free, easing congestion, and making transfers to and from other railway lines easier.

With its operational status still connected to the shopping mall, the station and platforms had to be moved 130 metres east to a new location. We were responsible for relocating the platform to the east, which included reducing the number of columns (from seven to three on the east side of the station) and constructing an island platform with rail services on both sides, which was originally a separate monorail platform.

New station: platform 12 metres wide, located between two tracks, wheelchair accessible via lift 
In addition, work on the platform connection began in 2009, in parallel with the redevelopment of the area around Shibuya Station. This project, which was carried out with the help of SketchUp 3D model BIM/CIM(*1), was highly evaluated and received the 2019 i-Construction Excellence Award from the Ministry of Land, Infrastructure, Transport and Tourism.

A total of 5,000 project participants worked on this massive project over the 6 days from 28 December 2019 - 2 January 2020.
Construction to accommodate the station relocation involved the replacement of three railway lines. The replacement of the railway lines required the temporary suspension of the Ginza Line, which increased the demands on the quality of the work. There were three main problems associated with the replacement of the railway lines:

(1) Time constraints
The construction period was only six days. The construction site was located in central Tokyo, and as part of the Shibuya Station redevelopment project, the construction had to follow a detailed plan and be coordinated with the opening hours of the Meiji-dori bus lane and traffic restrictions. Critical points had to be extracted and solutions developed and implemented quickly.

(2) Three-layer construction
Construction involved multi-layer crane work operations on the ground, track surface, and temporary structure surface. Three-tier construction operations are difficult to present using only two-dimensional drawings. In order to prevent the booms of each crane from colliding with each other, a detailed work plan for the boom rotation sequence was required.

(3) Reliable Information Sharing
With 5,000 project participants, complex and extensive plans, processes and procedures were required, and coordination between departments was key.
All workers involved in the construction had to be quickly and thoroughly informed about the complex construction schedule and processes. In addition, because track switching operations involving train shutdowns had to be completed within six days, all participants in the project had to have the same intuitive understanding of the work and a full understanding of the construction processes and procedures.

Deploying 3D modelling BIM/CIM to ensure accurate construction
In the past, under the traditional approach, if design issues were identified or a review of operability was required, requiring modifications or changes, there were issues with increased costs and delays in the schedule.
For this project, we asked the client to collaborate with us during the review process. During the schematic design phase, we used SketchUp to create a 3D model that included the contractor's perspective, and then implemented engineering design (*2) in parallel with the design through parallel consultation. In addition, we used the SketchUp 3D model to consult with the traffic department in advance on operational safety issues such as the location of signals.

Clear and easy communication is key. Two-dimensional documents make it difficult to communicate design intent and project sequencing, and SketchUp was used as a platform for coordinating information and sequencing among all the departments involved, each of which used its own set of files and timelines. sketchUp is a simple and flexible tool that every department can master in a short period of time. SketchUp was used for 3D modelling, removing any bias in understanding between departments.
In addition, by using VR (Virtual Reality) and 4D models for review, front-end work (*3) is achieved by adding timelines and movement on a minute-by-minute basis to the SketchUp 3D model. The focus of front-end work is to check the effectiveness of construction work and construction procedures at an early stage of the project so that decisions can be made quickly, rework can be avoided, and productivity can be increased by enabling consistent information to be shared among the many staff involved in the construction process.

Digital simulation (left) & on-site (right)
With this methodology, a reduction of about half the time required for the construction manager to understand the project was achieved. On a job-by-job basis, we have succeeded in reducing labour costs by about 60%.
Our company does not rely on external companies specialising in BIM/CIM. We used SketchUp, we developed a skills manual for our employees, and we gave initial training to more than 200 field engineers, thus allowing the construction site to take the initiative.

Leveraging SketchUp BIM/CIM not only improves productivity, but also provides additional benefits to clients, facility users, and others involved. We will endeavour to put the SUBIM workflow into practice, spreading it to construction sites and expanding it to the entire company.

Tokyu Railway Civil Engineering Department Director Interview Video
*1 BIM/CIM (Building/Construction Information Modeling, Management) is a workflow that starts from the research and design stage and deploys 3D models in the construction, maintenance and management stages. It is used for construction, production, and management of system families while adding attribute information (materials, strength, etc.) to ensure quality management and improve productivity.
*2 Concurrent Engineering (CE) is a methodology aimed at shortening development cycles and reducing costs through the simultaneous execution of multiple tasks in the development process in manufacturing and other industries, as well as the sharing of information and group work between departments. BIM is expected to have the following effects.

Ensure operability and quality after operation by reflecting the views of the construction manager and changes to plans at the design stage, improving appearance and comfort in the use of the facility.
Consideration of maintenance and management (e.g. materials, not setting up sections that may be weak) by reflecting the views of the person responsible for maintenance and management at the design stage. Providing the information required during the maintenance and management phase in a usable form during the design and construction phases improves the efficiency and level of maintenance and management.
Collaborative work by individuals involved in the project can speed up decision-making and reduce waiting time, thereby shortening the construction period and the duration of the entire project. (Ministry of Land, Infrastructure, Transport and Tourism CIM Guidelines General Edition).
*3 Front-end work, which is the consideration of possible changes in specifications for later processes, etc., ahead of time at the initial stage for the purpose of improving quality and shortening the construction period in the industry fields of system development and product manufacturing.

In the case of BIM, the desired effect can be achieved by changing specifications by checking reinforcement interference in RC structures and considering the effectiveness of temporary construction methods at the design stage, inspections by the construction side to prevent rework, inspections such as checking construction procedures, and inspections from the perspective of the maintenance and management side at the design and construction stages. (From the website of the Japan Construction Information Centre Foundation)