Updated 2026-10-09
The principle: standard interfaces, not vendor ones
Everything a traffic management center needs from a connected vehicle deployment is reachable through a published standard: the RSU over NTCIP 1218 (SNMPv3), the signal controller over NTCIP 1202 and 1211, other centers over TMDD, and the messages themselves as SAE J2735 in a documented JSON shape. An ATMS that speaks those interfaces does not depend on any RSU vendor's cloud or any one integrator's scripts, and an agency that specifies them in procurement can change vendors without rebuilding its center. This article lists the connectors, what each one gives you, and how the portal fits.
NTCIP 1218: RSU health and message store monitoring
NTCIP 1218 v01A is the RSU object standard. Poll it with the same SNMP monitoring your center already uses for signal controllers and dynamic message signs. The objects worth polling, by group:
| Group | Objects | What they tell you | Poll |
|---|---|---|---|
| System description | rsuID, rsuMibVersion, rsuFirmwareVersion, rsuLocationLat, rsuLocationLon, rsuLocationDesc | Identity and firmware for inventory; location for the map | daily |
| System status | rsuChanStatus, rsuMode, rsuModeStatus, rsuStatus, rsuPc5Status, rsuClockSource, rsuClockSourceStatus, rsuClockDeviationTolerance | Radio channel state, operating mode, C-V2X PC5 link state, time source health | 1 to 5 min |
| System statistics | rsuTimeSincePowerOn, rsuIntTemp, rsuIntTempLowThreshold, rsuIntTempHighThreshold, rsuCommRangeTable | Uptime (reboots), temperature, observed communication range per sector and message | 5 min |
| GNSS | rsuGnssStatus, rsuGnssLat, rsuGnssLon, rsuGnssElv, rsuGnssPositionError, rsuLocationDeviation, rsuGnssMaxDeviation, rsuGnssAugmentation | Fix quality and whether the RSU has drifted from its surveyed position; a bad fix means bad time and bad signing | 1 to 5 min |
| Radio | rsuRadioTable (rsuRadioEnable, rsuRadioType, rsuRadioCh1, rsuRadioTxPower1) | Radio enabled, channel and power as configured | hourly |
| Store and repeat | rsuMsgRepeatStatusTable (rsuMsgRepeatPsid, rsuMsgRepeatEnable, rsuMsgRepeatStatus, rsuMsgRepeatDeliveryStart, rsuMsgRepeatDeliveryStop, rsuMsgRepeatPayload) | Which MAP, TIM and RSM rows exist, whether they are enabled and inside their window; the payload for decoding in the portal | 5 min |
| Immediate forward | rsuIFMStatusTable (rsuIFMPsid, rsuIFMEnable, rsuIFMStatus) | Whether the SPaT and SSM path is enabled | 5 min |
| Message statistics | rsuMessageCountsByPsidTable (rsuMessageCountsByPsidId, rsuMessageCountsDirection, rsuMessageCountsByPsidCounts) | Transmit and receive counts per PSID; a SPaT count that stops is a dead controller link, a BSM receive count that stops is a dead radio | 1 min |
| Security | rsuSecEnrollCertStatus, rsuSecEnrollCertExpiration, rsuSecAppCertTable (rsuSecAppCertPsid, rsuSecAppCertState, rsuSecAppCertExpiration, rsuSecAppCertReq), rsuSecCertRevocationTime, rsuSecAppCertExpirationPending | Enrollment state, application certificate per PSID with its state and days to expiry, CRL freshness; see SCMS | hourly |
| Forwarding | rsuReceivedMsgTable, rsuXmitMsgFwdingTable | Whether received and transmitted messages are being forwarded, and where | hourly |
| Services and applications | rsuServiceTable (rsuServiceStatus), rsuAppConfigTable (rsuAppConfigState) | Vendor services and applications running or stopped | 5 min |
| Notifications | rsuNotifications group (rsuGnssAnomalyMsg, rsuTimeSourceLostMsg, rsuCertificateMsg, rsuWatchdogMsg, rsuEnvironMsg, rsuServiceDenialMsg) with rsuNotifyIpAddress and rsuNotifyPort | SNMP notifications the RSU pushes on events; point them at the center's trap receiver | event |
| SPaT objects (v01A) | rsuSpatTable, rsuSignalStatusTable, rsuMovementManeuverTable, rsuAdvisorySpeedTable | The signal state block the RSU holds for SPaT generation, readable for verification | as needed |
Vendors differ in how completely they implement the optional objects; compare against a known-good unit before alarming on an absent value, as the SCMS guide notes for the enrollment objects.
NTCIP 1202 v04: controller SPaT data
The controller's SPaT block (phase and overlap states with minimum and maximum time to change, intersection status) is defined in NTCIP 1202 v03 and extended in v04, which also specifies how the controller broadcasts it to the RSU or a roadside processor at 10 Hz. A center that polls the same objects at a lower rate gets controller status for its own displays and can verify that what the RSU broadcasts matches what the controller is doing; see how signal timing works.
NTCIP 1211: priority
The center's role in priority is policy and performance. NTCIP 1211 defines the request and status objects between the priority request server and the controller; a center that reads them (or receives the PRS's logs) can report requests, grants and strategies per intersection and route and can push policy tables (roles, levels, time windows) to the PRS. See signal priority.
TMDD v3.1: center to center
The Traffic Management Data Dictionary is how one center shares with another: an ATMS publishing signal status and events to a regional data hub, a transit center sharing vehicle locations with a traffic center. For connected vehicle data, TMDD carries the events (incidents, work zones) that become TIMs and RSMs, and the device inventory and status that let a regional center see RSUs alongside signals and signs. Specify TMDD when the RSU health and V2X message status should appear in a regional operations picture.
SAE J2735 over ODE and Kafka
The USDOT Operational Data Environment (jpo-ode) decodes J2735 from RSUs and OBUs into JSON records on Kafka topics, one per message type, and is the de facto back-office shape for pilot data. The portal's JSON for a MessageFrame is compatible with those records, so a center running the ODE can feed the portal's API or compare decodes, and the portal's JSONL export can be replayed into an ODE pipeline.
Data exchanges
Regional and national exchanges distribute TIMs, work-zone data and situation data so that vehicles with cellular connections get the same information the RSUs broadcast. The Situation Data Exchange (SDX) and its predecessor the Situation Data Clearinghouse (SDC) accept and distribute TIMs by region; the Work Zone Data Exchange (WZDx) feeds are the usual source for work-zone TIMs and RSMs. A center that generates TIMs for its RSUs should publish the same TIMs to the exchange so the information reaches vehicles out of radio range.
ATMS vendors' connected vehicle modules
Most ATMS products now ship a connected vehicle module that inventories RSUs, polls NTCIP 1218 health, pushes TIMs from the incident and work-zone screens, shows SPaT status, and logs priority. Judge a module by the interfaces above rather than its screens: does it use NTCIP 1218 for every RSU vendor, does it accept J2735 JSON, does it export the data to you, can it push to a data exchange. The portal is useful alongside any of them as the engineer's workbench for decoding, authoring and verification.
What the portal exposes today
| Interface | What it gives | Where |
|---|---|---|
| REST API | Decode, encode, templates, RSU registry, push, recordings and exports, with account tokens and quotas | API docs |
| Live stream (SSE) | Server-sent events of decoded messages for an account's RSUs as they arrive, for dashboards and scripts | API docs, live view |
| Exports | CSV, GeoJSON and JSONL of recordings and trigger hits, with the schema in live BSM and breadcrumbs | live view |
| Webhooks | HTTP POST on trigger hits (geofence, speed, hard brake, SRM, silence) to a URL you register | live view settings |
| RSU registry and map | Your devices with location, vendor, model and last push result | My RSUs, RSU map |
| NTCIP 1218 push | Store-and-repeat rows written from the creator and builder | NTCIP 1218 push |
What ITS Roads builds under a managed contract
- A dedicated instance of the portal on the agency's or ITS Roads' infrastructure, with a VPN to the agency network so RSUs forward over private addresses and the center's ATMS reaches the API without exposure to the internet.
- Enterprise monitoring of every RSU over NTCIP 1218 (the table above), the controller SPaT link, the security subsystem (certificate expiry, CRL freshness, enrollment state) and the backhaul, with alerting into the agency's existing monitoring and ticketing, and dashboards per corridor and per vendor.
- Connectors: NTCIP 1218 collectors for any vendor, NTCIP 1202 and 1211 readers for SPaT and priority verification, TMDD publishing of device status and events, ODE and Kafka integration, data exchange publishing of TIMs, and scheduled TIM and RSM generation from WZDx and incident feeds.
- Verification services: CTI 4501 checks of every MAP and SPaT, drive tests, plugfest preparation, FCC and SCMS administration (SCMS, FCC licensing).
Contact ITS Roads with your ATMS, your RSU vendors and your sites.
Data-flow table
| Data | Source | Interface | Destination | Rate |
|---|---|---|---|---|
| RSU health and configuration | RSU | NTCIP 1218 SNMPv3 get and walk | Center monitoring, portal RSU page | 1 to 5 min |
| RSU notifications | RSU | NTCIP 1218 SNMP notifications | Center trap receiver | event |
| MAP, TIM, RSM payloads | Center or portal | NTCIP 1218 rsuMsgRepeatTable set | RSU store | on change |
| SPaT | Controller | NTCIP 1202 SPaT block, UDP broadcast | RSU immediate forward | 10 Hz |
| Controller status | Controller | NTCIP 1202 get | Center ATMS | 1 s to 1 min |
| Priority requests and status | PRS and controller | NTCIP 1211 | Center logs and policy | event |
| Received BSM, PSM, SRM, SPaT | RSU | NTCIP 1218 rsuReceivedMsgTable forwarding (UDP) | Portal ingest or ODE | as received |
| Decoded messages | Portal | SSE stream, REST, exports | Center dashboards, researchers | real time and batch |
| Trigger hits | Portal | Webhook | Center ticketing or alerting | event |
| Events and work zones | Center ATMS, WZDx feed | TMDD, WZDx | TIM and RSM generation, data exchange | on change |
| Device status and events | Center | TMDD | Regional center | 1 min |
Related reading
- NTCIP 1218 v01A, NTCIP 1202 v03/v04, NTCIP 1211, TMDD v3.1, CTI 4001 and 4501; USDOT jpo-ode documentation; WZDx specification.
- NTCIP 1218 push, SCMS, live BSM and breadcrumbs, signal priority, research and pilots.