Building Code
Road Access Obligation
Road access obligation, or 接道義務（せつどうぎむ）, links a building site to legally recognized roads. It is a safety and access rule, not merely a site-area rule.
- Japanese Term
- 接道義務
- （せつどうぎむ）
Overview
Editorial ExplanationRoad access obligation asks whether a site is properly connected to a Building Standards Act road.
Road access obligation refers to the requirement that a building site must generally connect to a road recognized under the Building Standards Act. A common study expression is that the site must have at least 2 meters of contact with such a road. The key is to read this together with Article 42, which concerns the definition of roads, and Article 43, which concerns the site-road connection requirement.
It supports evacuation, firefighting, daily movement, and infrastructure before area calculations begin.
Exam Snapshot
Exam Reference- 1Ask two questions first: is it a road under Article 42, and does the site abut it as required under Article 43?
- 2When the problem shows a flagpole lot, private road, landlocked parcel, or narrow passage, check access length and road status first.
- 3Do not be distracted by site area. If access fails, later FAR or coverage calculations may be irrelevant.
- 4When the problem gives “2m,” identify whether it refers to contact length, passage width, or another dimension.
Required Terms
Core Diagram
Editorial ExplanationFuture Diagram
Variables & Terms
Editorial ExplanationTerms
- The core question is not only how large the site is, but whether it is safely connected to the legal road network.
- Article 42 of the Building Standards Act is important because it frames what counts as a road for this purpose.
- Article 43 is the usual study reference for the requirement that a building site abut a road. The 2-meter contact rule is a common foundation point.
- Road access supports evacuation, fire response, everyday movement, infrastructure, and urban safety.
- A large parcel without valid road access may fail before coverage ratio or FAR calculations become useful.
Applicability Check
Editorial Explanation- First check whether the adjacent path qualifies as a road under Article 42 or related official treatment.
- Then check the length of contact between the site and the road. For study purposes, at least 2 meters is the basic point to watch.
- Private roads, designated roads, existing narrow roads, exceptions, and local procedures can change the final judgment.
- Example: a 200 square meter site connected only by a very narrow passage may raise a road access issue if the contact is less than 2 meters.
- For real projects, municipal road records, official road classification, permit conditions, and local ordinances must be checked.
Calculation Process
Editorial Explanation- Step 1
Check road status
First decide whether the adjoining route is an Article 42 road or equivalent legal road.
- Step 2
Check access length
For study, watch the 2m-or-more access point.
- Step 3
Check special site forms
Flagpole lots, private roads, landlocked sites, and narrow passages require caution.
- Step 4
Move to area controls
Only after access is valid should BCR and FAR calculations become meaningful.
Worked Examples
ExampleBasic Example
Problem
2m access satisfied
Answer
A site touching an Article 42 road by at least 2m can proceed to later study checks.
Exam Example
Problem
Flagpole lot
Answer
Even with sufficient total area, the access strip width and legal road status must be checked first.
Examples
Example- Site A is smaller but has at least 2 meters of contact with a legally recognized road. Site B is larger but lacks valid access. In study terms, Site B may fail first.
- A path that looks like a street is not automatically a road under the Building Standards Act.
- Flagpole lots are common exam material because the issue is not total area alone, but the width and legal status of the access strip.
Comparison Table
Editorial ExplanationRoad Access vs FAR
| Road Access | FAR | |
|---|---|---|
| Question | Can the site safely connect to a legal road? | How much total floor area is allowed? |
| Exam order | Check first | Calculate after access is valid |
Exam Preparation
Exam Reference- Ask two questions first: is it a road under Article 42, and does the site abut it as required under Article 43?
- When the problem shows a flagpole lot, private road, landlocked parcel, or narrow passage, check access length and road status first.
- Do not be distracted by site area. If access fails, later FAR or coverage calculations may be irrelevant.
- When the problem gives “2m,” identify whether it refers to contact length, passage width, or another dimension.
- Remember the purpose: evacuation, fire response, and safe movement.
Common Mistakes
Editorial Explanation- Checking zoning and site area before confirming road access.
- Treating every walkable path as a legal road.
- Remembering 2 meters but forgetting that the road itself must qualify under Article 42 or related rules.
- Ignoring municipal road classification and local ordinances.
- Treating an educational explanation as a permit conclusion.
Memory Tips
Exam Reference- Before area calculations, ask: legal road and 2m access?
Next Topic
Related Glossary
Related Code Topics
Further Reading
- Building Standards Act Article 42
- Building Standards Act Article 43
- e-Gov Building Standards Act
- MLIT building regulation materials
Official Source
接道義務
建築基準法 第43条（要最終確認）
Official Source
接道義務
建築基準法 第43条（要最終確認）
- Regulation
- 建築基準法
- Article Number
- 建築基準法 第43条（要最終確認）
- Note
- 接道義務の根拠条文として扱う学習用参照。第42条の道路定義と合わせた最終確認が必要。
- Verification State
- Draft
- Last Reviewed
- Not Reviewed
接道義務
Guide reference
Government Guide
接道義務
Guide reference
- Regulation
- 国土交通省 建築基準法制度資料
- Article Number
- Guide reference
- Note
- 国土交通省が公開する建築基準法関連の制度資料。接道義務と道路の学習補助資料として扱う。
- Verification State
- Draft
- Last Reviewed
- Not Reviewed
道路
建築基準法 第42条（道路定義・要最終確認）
Official Source
道路
建築基準法 第42条（道路定義・要最終確認）
- Regulation
- 建築基準法
- Article Number
- 建築基準法 第42条（道路定義・要最終確認）
- Note
- 接道義務を判断する前提となる道路定義の学習用参照。道路種別と自治体の扱いは最終確認が必要。
- Verification State
- Draft
- Last Reviewed
- Not Reviewed
Educational Disclaimer
This content is provided for educational purposes. It is not legal advice and must not be used as the sole basis for permit applications, design approval, or legal determinations. Always consult official sources, local regulations, and qualified professionals.