Overview - ISO/TR 25221:2025 (Image‑based tolling measurable characteristics)
ISO/TR 25221:2025 is a Technical Report from ISO/TC 204 that analyses the processes and measurable characteristics of image‑based tolling systems used for electronic fee collection (EFC). The document identifies which characteristics of automated number plate recognition (ANPR) and other image-based technologies are relevant for tolling, where those characteristics manifest in the EFC process, and how they can be specified and measured. It focuses on discrete tolling systems (fixed identification points) and covers both geometrical variants such as free‑flow and constrained tolling.
Key topics and technical requirements
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Description of the EFC process broken into seven sub‑processes:
- Information and registration
- Passage detection
- Vehicle identification (ANPR/OCR)
- Classification (vehicle class for tolling)
- Verifications and reliability
- Payment
- Enforcement
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Identification and definition of measurable variables and performance metrics (KPIs), including:
- Detection rate and related metrics for false positives / false negatives
- Identification rate and ANPR verification practices
- Classification rate for vehicle categorization
- Association rates between identified licence plates and registered vehicles
- Verification system added value and verification error
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Framework for classifying discrete tolling systems and discussion of how multi‑technology deployments (e.g., DSRC combined with ANPR) affect measurable performance.
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Guidance on testing and performance evaluation: suitability of characteristic variables for conformance testing and KPI measurement.
Practical applications - who uses this standard
- Toll system designers and integrators: to specify measurable performance targets for ANPR and image‑processing components.
- Toll operators and transport authorities: to evaluate reliability, design enforcement workflows, and choose appropriate technologies for free‑flow or constrained sites.
- Test laboratories and certification bodies: to develop test suites and KPI‑based conformance tests for image‑based EFC equipment.
- Vendors and procurement teams: to prepare technical specifications and acceptance criteria for ANPR cameras, OCR engines, and verification systems.
- Standardization bodies and policy makers: to align regional/regulatory requirements (e.g., where OBEs are not required) with measurable performance metrics.
Related standards and context
- References and related documents mentioned in the report include ISO/TS 17573‑2 (EFC vocabulary) and background work like ISO/TR 6026 and regional standards (e.g., UNI 10772) addressing ANPR/OCR testing. ISO/TR 25221 complements these by mapping measurable characteristics across the full EFC process.
Keywords: ISO/TR 25221:2025, image-based tolling, ANPR, electronic fee collection, EFC, measurable characteristics, detection rate, identification rate, classification rate, KPIs, tolling systems.