News 18-01 (No.361)
Issued : January 25, 2018
Musashino Forest Sport Plaza Opens
By Akira Ono
The Musashino Forest Sport Plaza Campus (Photo credit: Miyagawa Corp.)
Musashino Forest Sport Plaza opened for public use in November, 2017. It is the first facility completed in Tokyo for the 2020 Olympics and Paralympic Games and is located in Tokyo’s Chofu City adjacent to the west side of Tokyo Stadium (Ajinomoto Stadium).
The basic project programming for both the Sport Plaza and the adjacent Tokyo Stadium was developed in April, 2009. At that time the goals for these facilities included contributing both to the promotion of sports activities in the Tama area of Tokyo and to area revitalization and development efforts by providing a large-scale venue that could also be used for concerts. This original project programming preceded the selection of Tokyo as the location for the 2020 Olympics. For this reason, when it was decided that the Sport Plaza will be used for the 2020 Olympics, the project was already in progress and able to complete before any other 2020 Olympic venue.
Moreover, the 2017-2018 Japan Figure Skating Championships competition was held in the new Musashino Forest Sport Plaza from December 22, 2017 to December 25, 2017. This competition selected Japan’s figure skating delegation to the upcoming PyeongChang Winter Olympics and attracted much media and public attention. As a result, Musashino Forest Sport Plaza has already become a well-known facility throughout Japan and beyond.
<< Project and Facility Overview >>
The architectural firm Nihon Sekkei was awarded the design and construction manager role for the project through a proposal submission process. A joint venture of five construction firms headed by Takenaka Corporation built the plaza’s main arena and a joint venture of four construction firms led by Kajima Corporation built the sub arena and indoor swimming pool. Nagata Acoustics provided acoustical consulting services during the design phase.
The plaza’s facilities for sports competitions include a main arena, sub arena and an indoor pool. In addition, the plaza has comprehensive fitness facilities and equipment. Overall, the plaza sits on 62,000 sq. meters (15.3 acres) of land and the campus has a total floor space of 51,000 sq. meters (550,000 sq. ft).
<< Main Arena Building >>
Exterior of Main Arena (Photo credit: Miyagawa Corp.)
Interior of Main Arena (Photo credit:
Metropolitan Tokyo Facilities website home page)
The main arena was developed and equipped as a multipurpose arena for volleyball, basketball, handball and futsal games as well as for other large-scale, competitive team sporting events and popular concerts. Triangular-shape panels form an openwork suspended ceiling above the main arena and provide sound absorption. To enable multipurpose use of the venue for both sports and popular concerts, the space above the triangular panels contains the venue’s stage lighting, theater battens and other stage equipment.
To enhance the sound absorbing properties of the ceiling, we specified the installation of a sound-absorbing surface against the interior side of the roof. When looking up at the ceiling from inside the arena, this additional sound absorbing surface is visible through the openwork pattern of triangles. Together with sound absorbing treatments on the arena’s walls, the ceiling’s sound absorption design successfully reduces the liveliness of the space. The resulting reverberation time of the arena measures 3.3 seconds at 500 Hz, an appropriately reduced reverberation characteristic for a venue of this large scale.
<< Sub Arena and Pool Building >>
Tokyo’s wide Koshu Kaido thoroughfare separates the main arena building from the sub arena and pool building. A pedestrian bridge connects the two buildings and facilitates access to the main arena’s entrance.
The sub arena’s floor space can accommodate two volleyball courts or two basketball courts. The floor can also be converted to flooring for judo and kendo use.
This building was also designed with facilities for individual use by the general public. The swimming pool and fitness center cost just ¥500 for up to three hours’ use with no membership fee required. The facility has already gained a large clientele of local residents who are enjoying this part of the campus.
<< Sound Isolation Considerations and Nearby Facilities for Seniors and Disabled Persons >>
As I mentioned above, the plaza’s project programming included use of the main arena for concerts and other music performances, as well as for competitive sports events. Accordingly, we based our sound isolation design for the facility on sound levels typical of sporting events and music concerts.
The buildings across the street from the north side of the main arena include housing for disabled persons and seniors, other welfare facilities and a preschool. From the start of our work on the main arena portion of the project, we knew that one requirement of the sound isolation design would be to ensure excellent sound isolation between the main arena and the nearby buildings to the north. We considered not only how to isolate sound from the north side of the main arena building, but also how to isolate sound generated through the roof and east and west sides of the main arena as well.
To ensure the desired level of sound isolation, we specified that the same increased sound isolation performance design we developed for the north wall also be implemented for the portions of the roof near the north side of the building. In addition, we specified the same sound isolation design for the east and west sides of the main arena building.
In deciding whether to develop special measures to address noise from event audiences as they leave the main arena at the end of a game or concert, we took into consideration the architectural design that located the main arena entrance on the building’s south side and provided access via the pedestrian bridge across the Koshu Kaido road. Because these architectural aspects of the project will effectively direct audiences away from the neighborhoods to the north, we determined that special measures would not be needed to contain noise generated by event-goers exiting the facility at the end of events.
<< Calculating a Project’s Sound Isolation Performance Needs >>
To calculate the sound isolation performance needs of a building, we must first make some assumptions about the sound volumes that will be generated by concerts performed in the building. Then we consider how much we must reduce those sound volumes to achieve the acceptable sound volume in the adjacent or nearby receiving location. The acceptable sound volume in the receiving location is known as the nominal value. The difference between these two values equals a building’s required level of sound isolation performance.
The sound volume of music concerts varies greatly by artist and genre, and can even vary greatly during a single performance, making it difficult to accurately predict the sound volumes of future concerts in a new space. Instead of hypothesizing about the future, we use data collected at rock concerts held in the past at appropriate other venues and extrapolate likely generated sound volumes from this data to obtain the sound volumes we use to calculate a new design’s needed sound isolation performance.
In the case of a large sports arena, such as Musashino Forest Sport Plaza (and also in the case of large convention centers), when music concerts are included as an intended use in the project’s programming, addressing the sound level concerns of adjacent neighborhoods and nearby buildings is essential. However, because of the large roof area of a large-scale sports arena or convention center, the cost of implementing a sound isolation design can be prohibitive. Extreme care should be given to planning and determining the appropriate level of sound isolation for a large-scale facility’s particular implementation. It is also desirable for the facility’s operational team to set policies for the maximum sound volumes that performers may generate in a facility of large size.
<< A Future of Both Olympic Use and Local Popularity >>
For the 2020 Olympics, the badminton games are scheduled to be held in the plaza’s main arena. Of the modern pentathlon games, fencing will be held at Musashino Forest Sport Plaza and the other four sports’ competitions (athletics, cycling, gymnastics and swimming) are scheduled for Tokyo Stadium. The Paralympics basketball games will also be held at Musashino Forest Sport Plaza.
Until the 2020 games begin—and after the 2020 Olympics and Paralympics end—the new Musashino Forest Sport Plaza can contribute to increased fitness activities by the local residents of the Tama area and help revitalize the community while providing a sports and fitness destination for individuals. The facility has made a good start towards becoming a well-used fitness center and arena. I hope it will continue to fulfill this role for many years to come.
More photos of the facility can be seen on the Musashino Forest Sport Plaza home page.
The URL is http://www.musamori-plaza.com/
Tetto Hall Opens in Kamaishi City, Iwate Prefecture
By Ryoichi Wada
Iwate Prefecture’s Kamaishi City is known in Japan as the birrthplace of the country’s modern steel industry. It is also the home of the Kamaishi Seawaves Rugby Team and will be the host city for the 2019 Rugby World Cup games. The stadium where the games will be held will complete and open in the summer of 2018. While the stadium has yet to receive its official name, it’s currently referred to as the Unosumai Kamaishi Recovery Memoral Stadium, a reference to the city’s incredible recovery from the 2011 Great East Japan Earthquake.
Kamaishi City was one of the hardest hit cities in the 2011 earthquake, and it is likewise one of the key focuses of recovery efforts to rebuild vitality in the region’s cities. Currently, in Kamaishi, the Front Project recovery master plan is in progress. One of the construction projects within the master plan is Tetto, Kamaishi’s new civic hall, which completed in December, 2017.
The new hall’s “Tetto” name was chosen from among suggestions submitted by the general public. The person submitting this name explained that it is appropriate for two reasons. First, in Italian, tetto means “roof” and one of the distinguishing characteristics of the new hall is the architectural design of its roof. Secondly, the spelling of “tetto” is a Japanese word consisting of two Kanji characters that together mean “steel city”, an appropriate appellation for Kamaishi City because of its association with the steel industry.
The architectural design for Tetto was provided by aat+makoto yokomizo architects, Inc. Nagata Acoustics provided the acoustical consulting services from the design phases through the completion of construction.
<< Tetto’s Distinguishing Characteristics—A Large Roof and Adaptable Spaces >>
Plan View of Tetto Hall
Section View of Tetto Hall
The layout of the new facility has a central common lobby for two halls, one at the north side of the lobby and the other at the south side. Hall A is located on the south side of the lobby. It has stadium-style, movable seating with 838 seats and a proscenium stage. Hall B, located on the north side of the lobby, is a flat-floor space with stackable chairs and can seat up to 200 persons.
Movable partition walls were used for the north and south walls of the lobby, as well as for the wall between Hall B and the North Plaza. When the partition walls are opened and Hall A’s stadium seating stored, the entire facility becomes a single large space. In addition, because the North Plaza has a roof extending over it to create a covered patio environment, Tetto can be used as a venue for outdoor events without concerns about the weather.
In typical hall designs, the performers’ dressing room area and the corridors that lead to it cannot be accessed by the general public or this area is designed in a way that make general access difficult. By contrast, the dressing rooms of Tetto’s Hall A were designed to make them fully accessible for other uses at times when the hall is not being used for a performance. The space has multiple paths of entry and egress. Tetto’s architectural design intentionally makes it possible to walk around the circumference of the entire hall. The shaded areas around Hall A in the accompanying plan diagram show the walkable path around the hall. When there is a performance in Hall A, a door to the corridor that leads to the dressing rooms on the west side of Hall A can also be closed to create additional space for the performers.
Beyond the corridor on the west side of Hall A there are the three studios A, B and C, as well as Tetto’s gallery space. This side of the building faces a main prefectural road. The studios and gallery will be used for creative activities such as music practice and exhibitions. The walls of these spaces are made of transparent glass. People inside the spaces can easily see the surroundings outside the building and people outside the rooms can see the activities taking place inside the rooms.
<< Sound Isolation Design >>
While Tetto’s architectural design makes it possible for the entire facility to be used as a single space, from the acoustical design perspective we naturally provided for each room to be used separately. By locating Hall A and Hall B at opposite north and south ends of the common lobby, the layout provides 20 m. (66 ft) between the two spaces and obtains the desired sound isolation performance between the two halls. In addition, we specified the installation of double-layer, sound isolating movable partition walls for the walls between the lobby and the halls.
Tetto’s layout maximizes the inclusion of many functions and rooms in a compact footprint, making it difficult for us to obtain sufficient sound isolation between studios A, B and C solely by physical separation. Given this constraint, we decided that loud sound volume activities such as rock band practice should be limited to Studio C, and we adopted an anti-vibration and sound-isolating structural design for this studio.
As I mentioned above, the walls of the studios are made of glass. To achieve the appropriate sound isolation performance with this material, studios A and B we installed double-pane glass that has a layer of air sandwiched between the two glass layers. Also, for the walls of Studio C, which has an anti-vibration and sound isolating structure, we adopted the use of triple-layer glass, with two of the layers being fixed, sound isolating glass and one layer specifically designed for anti-vibration sound isolation.
Interior View of Hall A
Detail of Hall A's Wall Surface of
Alternating Concave and Convex Sections
North Plaza Roof and Tape-Cut Celebration
Mini-Concert in Hall B (Lobby in Background)
<< Room Acoustic Design of Hall A >>
The configuration of Hall A is basically a rectangular “shoe-box” shape with a single slope in the audience seating area. On one side of the hall a recessed alcove provides balcony seating. The project programming for this hall prioritized classical music performance while also planning for events that use sound amplification, including ceremonies, lectures, dramatic performances and other events. To obtain clear and abundant acoustics for classical music performances, we specified a stage ceiling height of 15 m. (49 ft), and the architect adopted the specification.
Most of the wall surfaces of Hall A are finished with Laminate Veneer Lumber (LVL). LVL is an engineered wood material that is fabricated using a laminating process to join together thin layers of wood not more than several millimeters in thickness to other fibers placed in a parallel direction with the wood. In Hall A’s implementation, the LVL is affixed to a substrate of drywall. The drywall and LVL together form sufficient mass to provide the sound reflective wall surfaces necessary for the room acoustics design of the hall.
Using the LVL, we devised a fabrication method that gives Hall A’s walls a distinctive combination of convex and concave sections. Specifically, we had the LVL cut to create pieces with corrugated surfaces and we created an arrangement of offset concave and convex sections. The corrugated surface of the LVL has a texture that gives the hall a sense of warmth. When I enter Hall A from the common foyer, I feel as if I have entered the inner center of a wooden vessel hand-carved from a tree trunk.
<< Tetto’s Opening Ceremony and the Kamaishi Concert of Beethoven’s Ninth >>
On December 8, 2017, the city of Kamaishi held Tetto’s opening ceremony and immediately made use of the North Plaza’s covered outdoor design for the building’s tape-cutting ceremony. In Hall A, the event included a taiko drum performance by Mr. Chiho Tosha and a piano performance of Brahms’ Four Pieces for Piano by Kamaishi native Mr. Fumiya Koido. Even with the stage configured for the ceremonial portion of the program with the proscenium curtain in place, from my audience seat I heard both the piano and Japanese taiko drum music reverberating well in the hall’s acoustics and all of the soft and quiet tones reached my ears as well.
For the opening day’s events the partition wall between Hall B and the common lobby was stored to create an open space where visitors could easily come and go while musicians performed mini-concerts in the hall. This event drew many interested attendees enjoying the ease of being able to partake of the concerts and leave at will. The events in both halls showcased the features and functionalities of the new facility.
Following Tetto’s official opening day, on December 10, 2017, Tetto hosted the Kamaishi performance of Beethoven’s Ninth Symphony. The history of this concert dates back to the opening of the city’s former civic hall. Every year since the opening of that building, the residents of Kamaishi have participated in a performance of Beethoven’s Ninth Symphony. Even in the December after the old civic hall had been destroyed by the Great East Japan Earthquake, the concert was not abandoned. Instead, the venue was moved to the Kamaishi High School gymnasium and the annual concert performed.
The December, 2017 concert marked both the 40th anniversary concert and the inaugural concert of the city’s new Tetto Civic Center. Undaunted by the tragedy of the earthquake, the history of this music in this city continued to ring beautifully and robustly in the new hall. As a person involved in the construction of the new facility, I found this performance profoundly moving. For this concert, the hall’s sound reflection panel system had been set up and I had the opportunity to hear how this configuration also provided not only strong acoustics, but clear tones as well. The hall’s acoustics produce our design’s desired sound reverberations that linger appropriately and also deliver delicate sounds throughout the audience. Listening to this inaugural concert, I also heard the joyous tones in the singers’ voices as they sang in their recovered new home for the annual Beethoven’s Ninth performance.
Day by day, shops and eating and drinking establishments are beginning to reopen in the vicinity of Tetto Civic Center and the hustle and bustle energy of daily commerce has started to return. How will Kamaishi City make use of this new facility in the future? Surely, in the same way that the city has persevered in its tradition of an annual Beethoven’s Ninth concert. I hope that the many functionalities of the new facility will further the city’s resilient and ongoing, lively and abundant cultural activities and traditions.
Nagata Acoustics Inc.
Hongo Segawa Bldg. 3F, 2-35-10 Hongo
Bunkyo-ku, Tokyo 113-0033, Japan
Tel: +81-3-5800-2671, Fax: +81-3-5800-2672
1990 S. Bundy Drive, Suite 795
Los Angeles, CA 90025
Tel: +1-310-231-7878, Fax: +1-310-231-7816
75, avenue Parmentier
Tel: +33 (0)1 40 21 44 25, Fax: +33 (0)1 40 21 24 00