Hospital Accessibility & Inclusive Design Rules (HOSP-ACC)

Accessible circulation in healthcare facilities is essential for patient mobility, visitors, and clinical staff transporting heavy medical devices. All facilities must comply with BS 8300-2:2018 (Design of an accessible and inclusive built environment) and UK Building Regulations Approved Document M.

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1. HOSP-ACC-001: Healthcare Accessibility Ramp Gradient & Landings

Statutory Standard & Intent

• Standard: BS 8300-2:2018 Section 8 and Approved Document M Clause 1.26.
• Statutory Limits:
  • Maximum Gradient: $\le 8.33%$ ($1:12$) for ramp flights.
  • Level Landings: Intermediate level landing width $\ge 1.50\text{ m}$ ($1,500\text{ mm}$) when vertical rise $\Delta z > 0.20\text{ m}$.

Evaluation Logic (RampSlopeHandler)

1. Target Elements: Queries bis.PhysicalElement where class or label matches %Ramp%, %Stair%, %Slab%.
2. Dimension Extraction: Extracts local element dimensions ($L = \max(\Delta x, \Delta y)$, $W = \min(\Delta x, \Delta y)$, $\Delta z = \text{BBoxHigh.z} - \text{BBoxLow.z}$).
3. Slope Calculation: For elements where $L > 0.5\text{ m}$ and $\Delta z > 0.04\text{ m}$: $\text{Slope %} = \left(\frac{\Delta z}{L}\right) \times 100%$ Flags violation if $\text{Slope %} > 8.33%$ ($1:12$).
4. Landing Width: Flags violation if landing width $W < 1.50\text{ m}$ ($1,500\text{ mm}$) when $\Delta z > 0.20\text{ m}$.

Client-Configurable Parameters

{
  "nominalThreshold": 8.33,
  "maxSlopePercent": 8.33,
  "landingWidth": 1.50,
  "unit": "%",
  "comparisonOperator": "<="
}

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2. HOSP-ACC-002: Accessible Sanitary Wheelchair Turning Circle

Statutory Standard & Intent

• Standard: BS 8300-2:2018 and NHS Health Building Note 00-01 (Sanitary Spaces).
• Intent: Accessible toilets, assisted bathrooms, and shower rooms must provide an unobstructed circular footprint of not less than $1.50\text{ m}$ ($1,500\text{ mm}$) in diameter.

Analytical Detection: Maximum Inscribed Circle

Rather than relying on simple bounding boxes, BIM Checker computes the Maximum Inscribed Circle within the true 2D sanitary room boundary polygon. This accounts for structural columns, service shafts, and wall partition nibs to verify that an unobstructed $\ge 1.50\text{ m}$ ($1,500\text{ mm}$) diameter wheelchair turning circle is physically achievable per BS 8300-2 and NHS HBN 00-01.

If the inscribed clearance diameter drops below the statutory threshold, the system flags a defect and displays a 3D INSCRIBED_CIRCLE in the viewport highlighting the shortfall.

Client-Configurable Parameters

{
  "nominalThreshold": 1.50,
  "turningCircleDiameter": 1.50,
  "unit": "m",
  "comparisonOperator": ">="
}

Defect Message

"Accessible sanitary space 'WC-DIS-L1 [0x20000007b41]' clear turning dimension 1.28m fails the statutory 1.50m wheelchair turning circle required by BS 8300-2 & NHS HBN 00-01."

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What Must Be in the iModel (Revit & IFC Data Requirements)

Discipline	Element Category	Parameter / Property Set	Expected Value	Evaluated In
Architectural	Accessible Ramps (OST_Ramps / IfcRamp)	3D Solid Geometry	Slope $\le 8.33%$, Landings $\ge 1.50\text{ m}$	HOSP-ACC-001
Architectural	Sanitary Spaces (OST_Rooms / IfcSpace)	Name	Contains WC, Toilet, Bath, Shower, or Sanitary	HOSP-ACC-002
Architectural	Sanitary Spaces (OST_Rooms / IfcSpace)	2D Bounded Footprint	Closed room boundary polygon	HOSP-ACC-002

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Pre-Flight ECSQL Diagnostic Query

Verify accessible sanitary spaces and bounding dimensions:

SELECT 
  sp.ECInstanceId AS spaceId,
  sp.UserLabel AS spaceName,
  (sp.BBoxHigh.x - sp.BBoxLow.x) AS roomWidth,
  (sp.BBoxHigh.y - sp.BBoxLow.y) AS roomLength
FROM bis.SpatialLocationElement sp
WHERE (
  sp.UserLabel LIKE '%WC%'
  OR sp.UserLabel LIKE '%Toilet%'
  OR sp.UserLabel LIKE '%Bath%'
  OR sp.UserLabel LIKE '%Shower%'
)