04/14/2023
Research Report Meeting
At: Keidanren Hall

Social contribution project #2220

Actual circumstances of roundabouts in Japan
based on database development anddissemination of information regarding caseexamplesProject Leader: Hideki Nakamura (Nagoya University)
Keisuke Yoshioka (Nihon University)

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IATSS members

Special Researchers

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Hideki Nakamura (Project Leader, Professor, Graduate School of Environmental Studies, Nagoya University)
Koji Suzuki (Associate Professor, Faculty of Engineering, Nagoya Institute of Technology)
Junko Nagata (Professor, Graduate School of Urban Management, Osaka Metropolitan University)
Hidekatsu Hamaoka (Professor, Faculty of Engineering Science, Akita University)
Yoshinori Abe (General Manager, Road Planning Department, Infrastructure Management Business Unit, Kokusai
Kogyo Co., Ltd.)
Takeshi Ikeda (Division Leader, Road Safety Division, Road Traffic Department, National Institute for Land andInfrastructure Management)
Miho Iryo (Associate Professor, Graduate School of Environmental Studies, Nagoya University)
Katsumi Uesaka (Managing Director, Institute for Traffic Accident Research and Data Analysis)
Hiroshi Okushiro (Senior Chief Engineer, Road Traffic Department, Tohoku Branch, Central Consultant Inc.)
Nan Kang (Associate Professor, School of Transportation Engineering, Nanjing Tech University)
Nobuto Kanbe (Deputy General Manager, Transportation Division, Oriental Consultants Co., Ltd.)
Sumio Shimokawa (Professor, College of Science and Technology, Nihon University)
Tatsuo Takase (Associate Professor, Faculty of Engineering, Shinshu University)
Kenichi Takahashi (General Manager, Road I Division, Roads and Bridges Business Division, Mitsui Consultants Co.,Ltd.)
Xin Zhang (Lecturer, Graduate School of Environmental Studies, Nagoya University)
Michiko Matsumura (Representative, Town Creator / Advisor, IATSS)
Yoshihiko Miyasaka (Deputy Director, Road and Transportation Department, Tohoku Branch, CTI Engineering Co.,Ltd.)
Kazunori Munehiro (Chief Researcher, Cold Region Traffic Team, Civil Engineering Research Institute for Cold Region,
Public Works Research Institute)
Keisuke Yoshioka (Assistant Professor, College of Science and Technology, Nihon University)
Yoshiyuki Yoneyama (Senior Manager, Design Maintenance Division 1, Social Infrastructure Business Group, ChodaiCo., Ltd.)
Kazuki Watanabe (Deputy Director, Transportation Policy Department, Kanto Branch, Oriental Consultants Co., Ltd.)

Observers––

Kazushi Makiuchi (Manager, Regional Planning Division, Construction Department, Iida City)
Masuo Kondo (Deputy Manager, Regional Planning Division, Construction Department, Iida City)＊Affiliations as of March 2023

2

Japan Society of Traffic Engineers (JSTE)

IATSS Research Projects

2006-2008
JSTE RAB Research Committee

2009• Proposal for the conversion of anintersection to a RAB in Towa-cho, Iida
City
• Simulated RAB experiment on
Tomakomai Cold Region Test Road

2009 RAB planning and design
guide (draft) issued

2010• RAB conversion social
experiment in Azuma-cho,
Iida City

2011 Great East Japan Earthquake

2012• RAB conversion of a signalizedintersection in Towa-cho, Iida City

2012-2013 MLIT social experiment (Karuizawa)
2014 MLIT social experiment (Moriyama, Yaizu)

2013-2015• RAB conversion pre-/post-comparison
analysis• Technical proposals and participation invarious RAB plans/social experiments

2014.1. Establishment of the RAB Promotion Council

To the diffusion stageof RABs
2020-2022• RAB database development/analysis,
information provision

2014.8. MLIT Road Bureau Notification
2014.9. Enforcement of Revisions to the Road
Traffic Act

Diversification

2016 RAB manual issued

2021 RAB manual 2021 issued3



Total of 142 locations (as of March 2022)

140 locations in the National Police Agency
roundabout statistics (right-hand figure)+2 places that are operated as RABs in reality(priority and no disruption to circulatory traffic)

Miyagi Pref. (enlarged)

3枝
3-leg
4枝
4-leg
5枝
5-leg
6-leg
6枝
Kanto–Tokai (enlarged)

4

12

0
北海道檜山郡上ノ国町字大留
新潟県新潟市西蒲区角田浜
和歌山県田辺市龍神村柳1410-7
宮城県大崎市鹿島台平渡東銭神3-3
静岡県富士宮市上井出309-9
長野県下伊那郡高森町高森町下市田
北海道枝幸郡浜頓別町中央北
大分県宇佐市安心院
愛知県愛西市七川南157
兵庫県朝来市和田山町白井
福岡県宗像市上八島根県浜田市佐野町
岡山県加賀郡吉備中央町吉川
岩手県大船渡市末崎町鶴巻87-1
福島県相馬郡新地町谷地小屋釣師9-1
岡山県浅口市寄島町
愛媛県伊予郡松前町大字東古泉
宮城県石巻市大瓜棚橋
千葉県市原市鶴舞1054-51
山梨県南巨摩郡富士川町鰍沢
長野県須坂市大字野辺
静岡県駿東郡小山町大御神
熊本県宇城市松橋町豊福
茨城県坂東市富田
愛知県安城市和泉町井ノ上
兵庫県神戸市須磨区弥栄台1
香川県綾歌郡宇多津町浜一番丁
宮城県東松島市大曲下台
宮城県東松島市大曲下台
宮城県大崎市鳴子温泉沼井74-10
山形県長井市平山2191-2
富山県中新川郡上市町柿沢
宮城県亘理郡亘理町字遊里
静岡県焼津市下小杉
三重県伊賀市四十九町
栃木県大田原市狭原1223-222
埼玉県羽生市大字須影
新潟県南蒲原郡田上町大字田上
新潟県三条市帯織街苑
長野県須坂市大字沼目
長野県安曇野市豊科本村2027-2
静岡県焼津市関方
福井県三方郡美浜町山上
滋賀県守山市立田町
大阪府豊能郡能勢町平野
滋賀県蒲生郡日野町内池
熊本県上益城郡御船町小坂
熊本県上益城郡御船町小坂
山梨県北都留郡小菅村大久保
静岡県静岡市清水区市道北矢部日本平線
京都府福知山市夜久野町平野
長野県飯田市川路(天竜峡インター)愛知県豊田市猿投町神郷
島根県大田市朝山町朝倉(大田朝山IC)
福井県大野市蕨生 美濃街道
岐阜県安八郡安八町中
千葉県長生郡長柄町力丸
山形県村山市楯岡
愛知県豊田市矢並町法沢(鞍ヶ池SIC)
三重県多気郡多気町1
三重県多気郡多気町2
青森県八戸市大字河原木八太郎山官地
静岡県菊川市柳1
宮城県仙台市青葉区桜ケ丘4-33-10
愛知県一宮市栄1-11
鹿児島県いちき串木野市旭町124
福岡県北九州市八幡東区西本町4-13
千葉県市川市塩浜2
宮崎県日向市上町1
大阪府和泉市府中町1-3
静岡県浜松市東区天龍川町
茨城県日立市多賀町1-13
兵庫県豊岡市泉町6
沖縄県糸満市字糸満
群馬県安中市秋間みのりが丘2-32
兵庫県神戸市中央区港島南町6丁目
長野県飯田市鈴加町(吾妻町ラウンドアバウト)
長野県飯田市東和町1
鳥取県鳥取市今町１
宮城県仙台市泉区永和台15-4
千葉県千葉市稲毛区緑町2-16-5
沖縄県うるま市安慶名1-8
大阪府堺市北区新金岡町２
宮城県仙台市太白区八木山本町1-35-5
宮城県仙台市太白区日本平21-19
神奈川県横浜市港北区新横浜3-12-4
岩手県宮古市蛸の浜町1
神奈川県横浜市金沢区柳町31-8
宮城県塩竈市松陽台1-7-1
大阪府泉南市
宮城県仙台市宮城野区東仙台5-19
宮城県仙台市青葉区中山吉成2-8-1
宮城県仙台市青葉区中山吉成2-13
宮城県仙台市太白区ひより台46-35
宮城県仙台市太白区ひより台23
宮城県仙台市太白区中田町後河原3-10
東京都武蔵村山市大南5-1
埼玉県入間郡毛呂山町前久保南3ｰ21-27
埼玉県日高市高萩東2-29
埼玉県入間市大字上藤沢529-2
神奈川県横須賀市ハイランド1-56
静岡県浜松市浜北区内野台1-21
愛知県常滑市北汐見坂2-219
愛知県豊橋市曙町松波
大阪府堺市北区新金岡町2-4
愛知県名古屋市中区三の丸２丁目４栃木県宇都宮市西川田
愛知県岡崎市美合町
広島県広島市安佐北区可部東2丁目
宮城県仙台市青葉区川内27
東京都多摩市桜ケ丘1-80
長野県北佐久郡軽井沢町大字軽井沢(六本辻)
石川県かほく市白尾
大阪府箕面市彩都粟生北3丁目7長野県北佐久郡軽井沢町大字長倉1259-338(借宿)京都府南丹市八木町大薮小溝
大阪府堺市東区日置荘西町1-42
宮城県名取市相互台東2-2-20
宮城県名取市相互台1
宮城県名取市相互台2-1-1
宮城県名取市相互台2-15-9
宮城県名取市みどり台3
千葉県市原市有秋台東3
石川県加賀市大聖寺上福田町ロ(東側)石川県加賀市大聖寺上福田町ロ(西側)滋賀県米原市宇賀野
滋賀県草津市野路町
滋賀県草津市南笠町
奈良県奈良市中登美ケ丘
熊本県合志市竹迫

 Hierarchical clustering: Ward’s method
Suburban system(industrial or outside
zoning area)(residential/commercial/DID
designated)

Urban area

10

8

6

4

2

5

(A)
City center type青森県八戸市大字河原木八太郎山官地
静岡県菊川市柳1
宮城県仙台市青葉区桜ケ丘4-33-10
愛知県一宮市栄1-11
鹿児島県いちき串木野市旭町124
福岡県北九州市八幡東区西本町4-13
千葉県市川市塩浜2
宮崎県日向市上町1
大阪府和泉市府中町1-3
静岡県浜松市東区天龍川町
茨城県日立市多賀町1-13
兵庫県豊岡市泉町6
沖縄県糸満市字糸満
群馬県安中市秋間みのりが丘2-32
兵庫県神戸市中央区港島南町6丁目
長野県飯田市鈴加町(吾妻町ラウンドアバウト)
長野県飯田市東和町1
鳥取県鳥取市今町１
宮城県仙台市泉区永和台15-4
千葉県千葉市稲毛区緑町2-16-5
沖縄県うるま市安慶名1-8
大阪府堺市北区新金岡町２
宮城県仙台市太白区八木山本町1-35-5
宮城県仙台市太白区日本平21-19
神奈川県横浜市港北区新横浜3-12-4
岩手県宮古市蛸の浜町1
神奈川県横浜市金沢区柳町31-8
宮城県塩竈市松陽台1-7-1
大阪府泉南市
宮城県仙台市宮城野区東仙台5-19
宮城県仙台市青葉区中山吉成2-8-1
宮城県仙台市青葉区中山吉成2-13
宮城県仙台市太白区ひより台46-35
宮城県仙台市太白区ひより台23
宮城県仙台市太白区中田町後河原3-10
東京都武蔵村山市大南5-1
埼玉県入間郡毛呂山町前久保南3ｰ21-27
埼玉県日高市高萩東2-29
埼玉県入間市大字上藤沢529-2
神奈川県横須賀市ハイランド1-56
静岡県浜松市浜北区内野台1-21
愛知県常滑市北汐見坂2-219
愛知県豊橋市曙町松波
大阪府堺市北区新金岡町2-4
愛知県名古屋市中区三の丸２丁目４栃木県宇都宮市西川田
愛知県岡崎市美合町
広島県広島市安佐北区可部東2丁目
宮城県仙台市青葉区川内27
東京都多摩市桜ケ丘1-80
長野県北佐久郡軽井沢町大字軽井沢(六本辻)
石川県かほく市白尾
大阪府箕面市彩都粟生北3丁目7長野県北佐久郡軽井沢町大字長倉1259-338(借宿)京都府南丹市八木町大薮小溝
大阪府堺市東区日置荘西町1-42
宮城県名取市相互台東2-2-20
宮城県名取市相互台1
宮城県名取市相互台2-1-1
宮城県名取市相互台2-15-9
宮城県名取市みどり台3
千葉県市原市有秋台東3
石川県加賀市大聖寺上福田町ロ(東側)石川県加賀市大聖寺上福田町ロ(西側)滋賀県米原市宇賀野
滋賀県草津市野路町
滋賀県草津市南笠町
奈良県奈良市中登美ケ丘
熊本県合志市竹迫

Non-residential

Towa-cho,
Iida City

Residential

Schoolvicinity(B)
Educational
district type

Uruma City,
Okinawa Pref.

DIDspecified
Non-DIDspecified(C)
Residential district type
Okazaki City,
Aichi Pref.

6

北海道檜山郡上ノ国町字大留
新潟県新潟市西蒲区角田浜
和歌山県田辺市龍神村柳1410-7
宮城県大崎市鹿島台平渡東銭神3-3
静岡県富士宮市上井出309-9
長野県下伊那郡高森町高森町下市田
北海道枝幸郡浜頓別町中央北
大分県宇佐市安心院
愛知県愛西市七川南157
兵庫県朝来市和田山町白井
福岡県宗像市上八島根県浜田市佐野町
岡山県加賀郡吉備中央町吉川
岩手県大船渡市末崎町鶴巻87-1
福島県相馬郡新地町谷地小屋釣師9-1
岡山県浅口市寄島町
愛媛県伊予郡松前町大字東古泉
宮城県石巻市大瓜棚橋
千葉県市原市鶴舞1054-51
山梨県南巨摩郡富士川町鰍沢
長野県須坂市大字野辺
静岡県駿東郡小山町大御神
熊本県宇城市松橋町豊福
茨城県坂東市富田
愛知県安城市和泉町井ノ上
兵庫県神戸市須磨区弥栄台1
香川県綾歌郡宇多津町浜一番丁
宮城県東松島市大曲下台
宮城県東松島市大曲下台
宮城県大崎市鳴子温泉沼井74-10
山形県長井市平山2191-2
富山県中新川郡上市町柿沢
宮城県亘理郡亘理町字遊里
静岡県焼津市下小杉
三重県伊賀市四十九町
栃木県大田原市狭原1223-222
埼玉県羽生市大字須影
新潟県南蒲原郡田上町大字田上
新潟県三条市帯織街苑
長野県須坂市大字沼目
長野県安曇野市豊科本村2027-2
静岡県焼津市関方
福井県三方郡美浜町山上
滋賀県守山市立田町
大阪府豊能郡能勢町平野
滋賀県蒲生郡日野町内池
熊本県上益城郡御船町小坂
熊本県上益城郡御船町小坂
山梨県北都留郡小菅村大久保
静岡県静岡市清水区市道北矢部日本平線
京都府福知山市夜久野町平野
長野県飯田市川路(天竜峡インター)愛知県豊田市猿投町神郷
島根県大田市朝山町朝倉(大田朝山IC)
福井県大野市蕨生 美濃街道
岐阜県安八郡安八町中
千葉県長生郡長柄町力丸
山形県村山市楯岡
愛知県豊田市矢並町法沢(鞍ヶ池SIC)
三重県多気郡多気町1
三重県多気郡多気町2

Non-agricultural land area

Arterial road(D)
Suburbanarterial road type

Nishikan
Ward, Niigata
City
Higashimatsu
shima City,
Miyagi Pref.

Agricultural land area

Non-arterial
road
Nonexpressway IC(E)
district
Suburbannon-arterial
road type
Industrial

(F)
Rural
districttype

Expressway
IC(G)
Interchange
Connection
type

Yaizu City,
Shizuoka Pref.

Iida City,
Nagano Pref.

7

Miyagi Pref. (enlarged)

Kanto–Tokai (enlarged)8 Intended to be used as a reference for maintenance improvement by showing good
examplesMiyagi Pref. (enlarged)

Kanto–Tokai (enlarged)

9 Projects #2007A and #2107B‘Maintenance of Japan’s RAB database and case studies’– A database of 100 items of Japanese RABs in 130 locations nationwide andcase examples based on the database were systematically organised– Characteristics of their introduction, consensus building, application
situations, structures, and issues were clarified.

 Purpose of social contribution project #2220– Based on above results:
1) Development of online publishing system and 2) holding of
seminars relating to RAB databases are carried out.

• Disseminate information on knowledge and many interesting cases regarding actual
circumstances of roundabouts in Japan• Information on practical needs and issues gathered through opinion exchanges atseminars and fed back to database content– Through these activities, IATSS will contribute to society by promoting
desirable RABs that contribute to road traffic safety and sustainable
city/town development.
10 Significance of online publishing system– The introduction of RABs is increasing in various parts of the country,
but the full picture of the actual circumstances is unclear– Developing the RAB database and online publication system• Enables understanding of the actual circumstances of introduction cases inJapan• Enables the provision of information and support for future planning anddesign by comparing geometric structures and presenting good examples

 Main targets/expected usage– Road administrators and design engineers of local governments, etc.

• For local governments, etc., that are planning or considering introduction:
provide a foothold for introduction by presenting similar cases and good
examples to be used as a reference• For road administrators and consultant design engineers who are consideringgeometric structures: support design planning through comparison ofgeometric structures, etc.

– Release to the general public and researchers• Show the status of domestic RAB introduction on a map in an easy-tounderstand manner to improve recognition and understanding• Provide a comprehensive database of basic information such as the location
information of installation sites and major geometric structures to promoteresearch and survey activities

11 Database

Demonstration will be shown after this slide– Comprehensive coverage of basic information such as major geometricstructures and classification of location characteristics– Display of cards organised with main information and panoramic
photographs of each RAB– Good practices are evaluated with ‘★ or ★★’ and used as a reference forsample collection

 Publishing system based on online GIS– Color-coding and layer switching are enabled on the browser map by linking
with database information– Implemented on a dashboard that can create simple tabulations and graphs
in a browser– List display/keyword search and .csv output of the database are also
possible Ease of continuous updates– A system for administrators is also set up in which databases can be easily
added and modified on the browser map

 Other– Assuming on-site use, viewing on a smartphone is also supported
12

The purpose of the online
publishing system, notes onuse, usage methods, andexplanations of data are posted

13Color-coding change
・By location
characteristics
・By evaluation
・By number ofbranches

Background map andcolor-coding layerswitching
14

Keyword search based on common name,location (prefecture name, municipality name,etc.), and location characteristic classification

When clicked, the map
moves to the corresponding
location
A card can also be
displayed
15

When searching for a RAB with ‘Shizuoka Prefecture’,‘4-leg’, and ‘Inscribed circle diameter 20-30 m’
Output as .csv
data is also
possible

Display RABs that match the conditions
16

Tabulation by ‘Prefecture’, ‘Location
characteristics’, ‘Number of branches’,「静岡県」，「4枝」，「外径20～30m」のand ‘Evaluation’ is possible
ラウンドアバウトを検索した場合

Graphical display of thenumber of installation
locations by prefecture

17

Click to display card18‘★’ for good
examplesBasic
information

2022年度に幾何構造の改良工事を実施

Additional informationsuch as structural
improvements is included

Photograph

Classificationthat expresses
locationcharacteristics

Link toGoogle Map

19 Continuous updates and operation– Collection of information and continuous updating of the database evenafter the end of the project– Operated as a website covering information on RABs in Japan Utilization for various research– Utilization for various analyses such as the determination of the actual
circumstances of RABs in Japan, comparison with overseas cases, andlocation characteristics and geometric structure characteristics by region– Analysis results will also be published on the website in the future Public awareness activities– Deployment to local governments through the Roundabout Promotion
Council and Roundabout Summit

 Collaboration with overseas databases– Also considering mutual access to the database created by Kittelson and
Associates, Inc., in the U.S. (an English-language version of the site isalso being developed)– Sending information overseas

20 Number of participants: about 200 people21 Participants: approximately 200 people, mainly
administrative officials, such as those in local
governments, and private sector engineers

Venue: Nagai Civic Hall

 Contribution to information provision anddissemination through two lectures and threeposter presentations on the achievements of the
IATSS project
Report: Nagai City
Section Chief
Watanabe

Lecture: PL
Nakamura

Information provided by National Police
Agency: Deputy section manager Fujioka

Lecture: Special
Researcher Munehiro

Information provided by MLIT:
Section Chief Okubo

Report: Yamagata
Pref.

22

 Three poster presentations by special researchers on the achievements of the IATSS
project

Greetings from Nagai City
Mayor Shigeharu Uchiya

Hirayama-kosaka Roundabout,
Nagai City

On-site visit to Hirayama-kosaka
Roundabout

23




101 participants
Discussion and opinion exchange on urban development and community developmentthat make use of RABs based on information on the IATSS database24

Question
items

1.
2.
3.

4.

5.
6.

Overall symposium
About the symposium programme
Understanding of urban development
and community development thatmake use of roundabouts
Expectations for urban development
and community development thatmake use of roundabouts
Requests for holding future seminars,
etc.
Respondent attributes

SurveymethodOnline questionnaire

Response
period2022/12/8 (Thu.)–16 (Fri.)

Response
rate

Seminar participants: 101 people(excluding related parties)
Respondents: 67 people
Response rate: 66.3%

25

■ Respondent attributes■ Feelings toward seminar
0.0% 0.0%⑤その他民間
1.5%④コンサルタント
32.8%①非常に有意義であった②有意義であった

40.3%
59.7%

③大学・研究機関
0.0%③どちらともいえない①道路行政関係62.7%④有意義ではなかった

②警察関係
3.0%

N＝67

①道路行政関係②警察関係④コンサルタント⑤その他民間③大学・研究機関■ Expectations for roundabouts
0所属①道路行政関係

回答者数 [人] 構成比 [%]

10

20

30

①災害時の機能確保（災害に強い）

39

42

62.7%

②シンボル機能（地域のランドマーク）

②警察関係

2

3.0%

③安全性の機能向上③大学・研究機関

00.0%④快適性の機能向上④コンサルタント

22

32.8%

⑤生活道路の安全対策

23⑤その他民間1

1.5%⑥道路の機能変化の位置づけ

23

67

100%

⑦環境負荷の軽減

合計

36
38
10

6

⑧維持管理のし易さ
その他

回答者数 [人]
40
50

10
0
※複数回答可(最大3つ)

26 Main opinions– Various national cases, such as the history of introduction
and community changes before and after introduction– Contribution to community development through theutilisation of the central island and structure that issuitable for symbol marking– Issues after the start of service and case studies ofsolutions– Problems that arose during the adjustment phase or after
implementation– Disadvantages and shortcomings– Safety measures and ease of understanding from theperspective of pedestrians crossing the road– Establishing an award system is also meaningful for wide
deployment– Please allow enough time for Q&A
27

 Results of this project– Development of an online publishing system for RAB DB– Provision of information and exchange of opinions by hosting seminars
Provided information on research and survey results to local governments andcitizens and made social contributions toward the development of safe, secure,and sustainable road transportation

 Impressions and issues that arose through this project– Importance of continuous information dissemination•

Sufficient information needs to be provided for issues as well

– Importance of town and community development through thestrategic placement of RABs on the road network in Japan, where
natural disasters frequently occur•

Consideration of the functional hierarchy of roads– Progress regarding introduction has been mainly on middle- andupper-level roads, but the application of RABs as a device forlower-level community roads and narrow streets is also achallenge•••

Functions and structures to accommodate various road users arenecessary
Promotion of organic applications in combination with speed bumps,
bottlenecks, smooth pedestrian crossings, etc.
It is necessary to examine cost-saving compact structures according
to the application environment

28