The CAD-QA Index (https://index.itwin.app/cadqa-index) provides automated, model-by-model quality assurance for CAD and federated BIM deliverables ingested into Bentley iTwin.
While Class Index and Asset Index evaluate object-level BIM property completeness and classification hierarchies, major UK infrastructure authorities—such as Network Rail (NR/L2/INI/EDT/CP0091 Issue 4), National Highways (DMRB GG 184), and NHS England (ISO 19650-2 UK National Annex)—enforce strict CAD deliverable hygiene gates across .dgn, .dwg, and federated model containers before any Common Data Environment (CDE) submission can transition from Work in Progress (S0) to Shared (S1–S4) or Published (A1–An).
| Guide | Purpose |
|---|---|
| 1. Overview & Architecture | The 3-Pillar Rule Contract (Target • ECSQL • RAG Gate), 4-Level Hierarchical Scoring (Rule -> Model -> iModel -> iTwin), and Amber Variation governance. |
| 2. View — Model Deliverable Assurance | Running per-model CAD-QA audits, interpreting RED / AMBER / GREEN assurance gates, inspecting rules in Bentley iModel Console, exporting 22-column sign-off checklists (CSV / JSON), and publishing runs. |
| 3. Report — iModel & iTwin Rollup | Executive Level 3 iModel analytics charts and Level 4 iTwin Portfolio Rollup across multiple discipline containers. |
| 4. Configure — Target • ECSQL • RAG | Customizing regex parameters, using the 12 BIS Target Dimension templates, authoring parameterized ECSQL rules, recording Approved Amber Variations, and forking custom authority profiles. |
| 5. Public UK Authority Rule Catalog | Complete clause-by-clause reference of the 26 shipped preset rules across Network Rail CP0091 Issue 4 (17 rules), National Highways DMRB GG 184 (5 rules), and NHS Digital Estate ISO 19650-2 (4 rules). |
Instead of hardcoding authority-specific TypeScript handlers that require software releases whenever a client updates a naming standard, every CAD-QA rule in Digital Index is governed by a declarative 3-Pillar Contract stored in the configuration service:
target (BIS Inspection Dimension): Declares what structural or graphical aspect of the synchronized CAD/BIM container is being audited across 12 canonical target templates (repository_link, model_structure, spatial_category, drawing_category, discipline_homogeneity, spatial_coordinates, subcategory_symbology, sheet_border_and_tags, annotation_placement, cell_usage, construction_geometry, and custom_ecsql).ecsql + parameters (Parameterized Query): Every rule executes a self-contained ECSQL query with named {paramName} tokens (such as {levelRegex} or {modelRegex}). Teams can override regular expressions or coordinate bounds in the UI without rewriting SQL, or author custom ECSQL returning (modelName, elementCount, goodCount, badCount).rag & weight (Assurance Gate Severity):RED — BLOCKER (Default Weight 2.0x): Mandatory contractual requirement. No variation is permitted; any rawScore < 100% marks the deliverable model RED (Rejected).AMBER — VARIATION (Default Weight 1.0x): Standard requirement where project-specific variations are permitted when approved in writing by the Information Manager / BIM Manager (for example, Network Rail CP0091 Clause 4 TRACKER variations or National Highways DMRB GG 101 Departures). Recording an approved variationRef adjusts the rule's weighted score contribution to 100% (status: VARIATION) while keeping the model's gate badge transparently marked AMBER for audit traceability.GREEN — COMPLIANT (Default Weight 0.5x): Best-practice advisory indicator.Rule -> Model -> iModel -> iTwin)Unlike object-only property audits, CAD quality assurance is signed off per deliverable CAD file (bis.RepositoryLink) before rolling up to the federated container and project twin:
For each deliverable model $m$ and active rule $r$:
$s_{m,r} = \begin{cases} 1.0 & \text{if } r \text{ is Amber with an approved Variation Reference} \ \dfrac{\text{goodCount}{m,r}}{\text{goodCount}{m,r} + \text{badCount}_{m,r}} & \text{when evaluated elements } > 0 \end{cases}$
(Rules returning zero applicable elements or querying optional BIS classes absent from a 3D-only container—such as bis.Sheet—are marked N/A and excluded from that model's weighted denominator so deliverables are never unfairly penalized.)
Each CAD deliverable file receives a severity-weighted compliance score:
$S_m = \frac{\sum_{r \in R_{\text{active}}(m)} w_r \cdot s_{m,r}}{\sum_{r \in R_{\text{active}}(m)} w_r}$
RED: Any RED rule on model $m$ has rawScore < 1.0.AMBER: All RED rules pass (1.0), and one or more AMBER rules have rawScore < 1.0 (including recorded variations).GREEN: All RED and AMBER rules achieve 100% raw compliance.At the federated iModel level across $|M|$ deliverable CAD models:
Aggregates the latest CAD-QA runs across multiple discipline or geographic zone iModels within the active iTwinId on the Report tab.
Out of the box, CAD-QA Index includes 3 Public UK Authority Presets (26 pre-configured rules total):
network-rail-cp0091, UK_NR): 17 rules mapped to NR/L2/INI/EDT/CP0091 Issue 4 and NR/L3/INI/P3M/131/02 (9 RED mandatory blockers, 8 AMBER variation-eligible rules).national-highways-gg184, UK_NH): 5 rules mapped to Design Manual for Roads and Bridges GG 184 and BS 1192 / Uniclass 2015 layer conventions.nhs-digital-estate-cadqa, UK_NHS): 4 rules mapped to BS EN ISO 19650-2 UK National Annex (NA.2) container naming, category hygiene, datum bounds, and construction geometry purge.Need HS2, Transport for London (TfL), Environment Agency, or a bespoke joint-venture CAD standard? Use Fork as Custom Authority Config on the Configure tab to clone any preset and tailor its regexes, coordinate bounds, and ECSQL rules in seconds.