A decade ago, parking data flowed between systems primarily through custom integrations and PDF reports. The current landscape is radically different. A handful of open data specifications now cover facility data, real-time availability, curb regulations, mobility device trips, and payment transactions. Interoperability is no longer aspirational; it is operational infrastructure.
The proliferation of standards has introduced its own confusion. Most facility and city operators could benefit from a clearer map of which specification covers what.
APDS: Alliance for Parking Data Standards
The Alliance for Parking Data Standards, a joint effort of IPMI, the British Parking Association, and the European Parking Association, maintains the APDS specification — a comprehensive data model covering parking facilities, availability, pricing, reservations, and access events. APDS is the closest thing the industry has to a common facility-data lingua franca.
APDS is relatively mature (version 2.x is in production use) and is the foundation of data exchange between parking systems, navigation platforms, and third-party aggregators. Major parking management system vendors and most navigation-platform feeds either implement APDS directly or use it as a translation intermediate.
Strengths: comprehensive coverage of facility-level data; governed by neutral industry bodies; active versioning.
Limitations: relatively heavy specification; implementation quality varies significantly across vendors; real-time extensions are less consistently supported than static facility data.
NAPIS and On-Street Parking Data
For on-street parking, the National Association of City Transportation Officials and related bodies have supported the National Parking Information System (NAPIS) concept and related specifications. In practice, on-street data exchange has coalesced around several more narrowly scoped specifications:
- CurbLR (curb regulations in machine-readable form)
- SAE Curb Data Specification (CDS) (curb use events, increasingly the dominant standard)
- Open311 and related municipal feeds (reports, service requests)
The SAE CDS in particular has emerged as the preferred framework for cities exchanging curb-use data with ride-hail, delivery, and mobility platforms. The specification covers regulation, event, and metrics data, with separate APIs for each.
MDS: Mobility Data Specification
The Mobility Data Specification, maintained by the Open Mobility Foundation, is not a parking standard in the traditional sense, but it intersects meaningfully with curb and parking operations. MDS defines how cities receive trip and vehicle status data from shared mobility providers — scooters, bike share, and increasingly other fleet operators.
Parking implications are mostly indirect: MDS-compliant data supports curb-use analysis, dedicated micromobility parking siting, and coordination between vehicle-share operations and parking facilities. Cities with mature MDS implementations generally have a richer picture of curb demand than cities relying only on traditional parking data sources.
GBFS and General Bikeshare
The General Bikeshare Feed Specification is a real-time feed standard for docked and dockless bikeshare. It is older than MDS, simpler in scope, and widely implemented. For parking operators integrating bikeshare into mobility-hub offerings, GBFS is usually the relevant reference.
Payment and Transaction Standards
Payment-layer standards — EMV, PCI DSS, tokenization protocols — are separately governed and intersect with parking data standards only at the interface. Integration between payment data and facility-level APDS feeds remains an area where custom work is common.
Where Interoperability Actually Breaks
Despite the specification landscape, practical interoperability still breaks down in predictable places.
Vendor implementation quality. A specification is only as useful as its implementation. Several major parking systems expose APDS endpoints that are technically compliant but semantically inconsistent — field meanings vary, event timing varies, and null-handling varies.
Version drift. Specifications evolve; operator systems often do not. Production integrations routinely run on specification versions three or four releases behind current.
Governance gaps. Some data that operators and cities need — loading zone compliance events, EV charging session data, permit-level utilization — sits between specifications or is not yet covered.
Authentication and data-sharing agreements. Even where technical specifications exist, contractual barriers (vendor-to-vendor data sharing, privacy-law constraints, concession exclusivity provisions) frequently block exchange that would otherwise be technically trivial.
What Operators and Cities Should Prioritize
For operators evaluating interoperability investments, a pragmatic priority order tends to be:
- APDS-compliant facility data export, with active maintenance through version changes
- SAE CDS for cities engaging with curb management and micromobility platforms
- Participation in governance processes (APDS, Open Mobility Foundation) to shape future revisions
- Contractual frameworks for data sharing that anticipate future standards rather than hardcoding current ones
Skipping step four produces integrations that are technically sound but legally brittle.
FAQ
What is the difference between APDS and MDS?
APDS is a parking facility data specification, covering facility attributes, availability, pricing, and access events. MDS is a mobility specification covering shared-vehicle trip and status data. They overlap in curb and mobility-hub contexts but address different primary use cases.
Is there a single standard for on-street parking data?
Not quite, but the SAE Curb Data Specification has emerged as the dominant framework for curb regulation and use-event exchange. CurbLR covers the regulation-inventory side and is often used in conjunction with CDS.
How mature is APDS adoption?
APDS v2 is in production with major vendors and navigation platforms. Implementation consistency across vendors is the remaining weakness; most serious integrations include normalization layers to handle vendor-specific quirks.
Where are these standards governed?
APDS by the Alliance for Parking Data Standards (IPMI, BPA, EPA). MDS and CurbLR by the Open Mobility Foundation. CDS by SAE International. GBFS by MobilityData. Operators implementing any of these benefit from engaging with the relevant governance bodies.