US 11780481

I'll search for this specific patent number to check the USPTO record and any CAFC 2026 litigation activity.

Let me run a couple more targeted searches to check for any proceedings specifically involving this patent number.

US Patent 11,780,481 — Analyst Summary

Confidence note up front: I could not locate any USPTO proceeding (IPR/PGR) or CAFC docket in which US 11,780,481 itself is the challenged or asserted patent. The 2026 CAFC activity involving the same patent owner, Metrom Rail, concerns different patents (see "Related litigation" below). The bibliographic and claim details below are taken from the patent's own full text/front page as provided, cross-checked against secondary listings.

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Bibliographic data

Priority chain (as recited in the '481 specification): continuation of 16/910,804 (filed Jun 24, 2020, granted as US 11,492,027 B2), which claims benefit of provisional 62/865,688 (Jun 24, 2019) and is a continuation-in-part of 16/460,302 (Jul 2, 2019, granted as US 10,926,783 B2), which is a continuation of 15/623,996 (Jun 15, 2017, granted as US 10,336,353 B2 — which also claims provisional 62/350,520, Jun 15, 2016), which is a CIP of 15/078,427 (Mar 23, 2016, granted as US 10,179,595 B2), which claims provisional 62/177,683 (Mar 23, 2015).

Family (continuations of the '481):

• US 18/377,971 → granted as US 12,122,436 B2 (Oct 2024)
• US 18/921,581 → published as US 2025/0050921 A1 (pending)

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Abstract (verbatim)

"Systems and methods are provided for worker protection system with ultra-wideband (UWB) based anchors. One or more wayside units placed on or near a track may be configured to form a work zone network, based on ultra-wideband (UWB) communications, corresponding to a work zone in an area surrounding or in proximity to the one or more wayside units. When the work zone network is formed, at least one wayside unit of the one or more wayside units may be configured to obtain ranging information to a train traversing the track, based on communications of UWB signals with at least one train-mounted unit deployed on the train, and the one or more wayside units are configured to generate, based on the ranging information, notifications relating to the train and/or the work zone."

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Independent claims — plain-language overview

The patent carries 18 claims, of which only claim 1 is independent. Claims 2–18 are all dependent (2–14 and 15–16 depend from claim 1; 17 depends from claim 1; 18 depends from claim 17). There is no second independent claim.

Claim 1 — the only independent claim. It is a system claim with three required elements:

1. A remote server located in a back office of a railway network — i.e., a central/dispatch-side computing system.
2. A wayside unit placed on or near a track, containing circuitry configured to (a) transmit and/or receive wireless signals that include ultra-wideband (UWB) signals, and (b) process those transmitted/received signals.
3. The wayside unit must further be configured to perform three things:
   • form, or become a node in, a work zone network using UWB communications, where the network corresponds to a work zone around or near the unit;
   • when that network is formed, generate notifications about the train and/or the work zone based on ranging information to a train traversing the track (note: claim 1 itself does not expressly recite that the ranging is done against a train-mounted unit — that requirement appears in dependent claim 18); and
   • communicate with the remote server to send and/or receive information or messages relating to the work zone network.

Practical read: the independent claim is directed to a wayside/anchor-based UWB worker-protection architecture that is tied to a back-office server, where the anchor both forms an ad-hoc "work zone network" and generates train/work-zone notifications from UWB ranging, while also exchanging work-zone information with the back office. The claim is broad in that the back office is only required to be a "remote server … in a back office" and the claim does not limit how the work zone is activated (worker detection vs. remote command) — those are optional dependent features.

Notable dependent claims (for scope context, not independent claims):

• Claim 2 — wayside unit is a pre-installed anchor at a particular location.
• Claim 4 — notifications sent to a train-mounted unit.
• Claim 5 — notifications include control information for controlling train operation, sent to a train-mounted unit.
• Claim 6 — notifications include alerts provided to workers on/near the track.
• Claim 7 — wayside unit reports ranging info / data derived from it / notifications to the remote server.
• Claim 8 — wayside unit receives configuration/control information from the remote server.
• Claim 9 — work zone network forms in response to detecting a worker's personal device.
• Claim 10 — work zone network forms in response to commands from the remote server.
• Claims 12–14 — remote server remotely configures the work zone and assigns a work-zone speed / operational parameters.
• Claims 15–16 — a communication backbone connects the wayside unit to the remote server (and also interconnects back-office components).
• Claims 17–18 — wayside unit obtains ranging information from UWB signals; specifically via UWB communications with a train-mounted unit on the train.

Key point (from the specification, relevant to claim interpretation): the terms "anchors" / "anchor network" are defined to cover both fixed/pre-deployed UWB anchors and portable UWB wayside units deployed temporarily at work sites, and portable "tripod" units are expressly described as a fallback where no anchor network is available.

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Related litigation context (⚠️ do NOT conflate patent numbers)

Metrom Rail, LLC is a prolific patent litigant, so it is easy to attribute the wrong case to the '481:

• Metrom Rail, LLC v. Siemens Mobility, Inc., Nos. 2024-2223, 2024-2236, 2024-2264 (Fed. Cir.) — nonprecedential opinion decided May 11, 2026 (Judge Dyk, with Judges Mayer and Taranto; Taranto concurring-in-part/dissenting-in-part). This appeal addressed U.S. Patent Nos. 9,043,131 (the '131 patent) and 8,812,227 (the '227 patent) — not 11,780,481. The court affirmed the Board's obviousness holdings as to all '227 claims and '131 claims 1–16, and reversed the Board as to '131 claims 17–20. Metrom's AURA CAS product was the asserted commercial embodiment; the court agreed with the Board that the nexus presumption for secondary considerations failed because AURA CAS had significant unclaimed features. CourtListener docket: https://www.courtlistener.com/docket/69956488/metrom-rail-llc-v-siemens-mobility-inc/; opinion: https://law.justia.com/cases/federal/appellate-courts/cafc/24-2223/24-2223-2026-05-11.html; CAFC page: https://www.cafc.uscourts.gov/2026/05/11/page/2/
• The underlying IPRs were IPR2023-00468 and IPR2023-00470 (petitioners: Siemens Mobility, Ground Transportation Systems USA / Hitachi Rail GTS USA, Humatics Corp., Piper Networks; real party in interest also listed as Thales USA).
• Related district court actions referenced in the IPR record: D. Del. No. 1:22-cv-00049-RGA (transferred to S.D.N.Y. and severed), and S.D.N.Y. Nos. 23-cv-02920-DLC and 23-cv-03057-MKV.
• None of the 2026 CAFC docket entries I retrieved reference US 11,780,481.

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Uncertainty / caveats

• I have no authoritative confirmation of any IPR, PGR, ITC investigation, or district court or CAFC appeal naming US 11,780,481 as an asserted or challenged patent as of the search date. Absence of such a hit in my searches is not proof that none exists.
• The "Anticipated expiration 2036-03-23" and "Active" status entries are the Google Patents legal-status field and are explicitly disclaimers-of-record, not legal conclusions.
• Claim 1's recitation of "ranging information to a train" is textually silent on the UWB train-mounted counterpart; that limitation is introduced only in claim 18. Any infringement/validity analysis should not read claim 18's limitation into claim 1.
• The specification contains a set of paragraphs beginning "An example system for worker protection, in accordance with the present disclosure, comprises…" that read like claim language but are description text, not the issued claims; the operative claim set is the 18 claims reproduced in the patent's Claims section.

I'll search for litigation involving US patent 11780481.

Let me search more targeted litigation databases.

Let me search for whether the '481 patent specifically was asserted in these cases.

Bottom line

Based on my searches, I found no litigation specifically involving U.S. Patent No. 11,780,481 ("the '481 patent"). I could not identify any complaint, docket, IPR, ITC investigation, or CAFC appeal in which the '481 patent is named as an asserted or challenged patent. In particular, my searches did not surface the '481 patent as an asserted patent in any of the Metrom Rail cases that did appear.

I want to be explicit about the limitation here: the absence of results is not proof that no such litigation exists. Google Patents' litigation links, Unified Patents, and PACER-crawled pages do not always surface every assertion, and I was unable to complete a full run of targeted docket queries. So treat this as "none known/found," not as a certified negative.

What I actually found (and why it does not answer your question)

My searches surfaced active litigation by the patent's owner, Metrom Rail, LLC (the assignee of the '481 patent). However, in every instance where the reporting identified the asserted patent numbers, they were different patents — notably the '738, '131, '227, and '302 patents — not the '481 patent. Per your instruction to interpret identifiers literally and not return similar numbers, I am flagging these as related-company litigation on different patents, not as '481 litigation:

The asserted patents identified in these matters are the '227 patent (U.S. 11,492,027), the '131 patent, the '738 patent, and the '302 patent. The '481 patent — the subject of your query — is a continuation of the '227 patent within the same Metrom Rail family, but I found no record of it being asserted or challenged.

Sources consulted:

• Finnegan / Mondaq / Lexology, "D. Mass. Patent Litigation Update: December 2025" — https://www.finnegan.com/en/insights/articles/d-mass-patent-litigation-update-december-2025.html
• CourtListener docket, Metrom Rail, LLC v. Massachusetts Bay Transportation Authority, 1:25-cv-10417 (S.D.N.Y.) — https://www.courtlistener.com/docket/72043751/metrom-rail-llc-v-massachusetts-bay-transportation-authority/
• CourtListener, Memorandum & Opinion #113 (5/20/2026) — https://www.courtlistener.com/docket/72043751/113/metrom-rail-llc-v-massachusetts-bay-transportation-authority/
• Fed. Cir. nonprecedential opinion, Nos. 2024-2223/2024-2264 (5/11/2026) — https://cafc.uscourts.gov//opinions-orders/24-2223.OPINION.5-11-2026_2691571.pdf
• PTAB stay briefing, Metrom Rail v. Siemens Mobility / Humatics (S.D.N.Y.) — https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1556106](/patent/1556106)/download-documents?...
• D. Del. docket, Metrom Rail, LLC v. Siemens Mobility, Inc. et al, 1:22-cv-00049-RGA — https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1550896](/patent/1550896)/download-documents?...

Caveats / recommended next steps

1. No '481 assertion confirmed. None of the retrieved records list U.S. 11,780,481 among asserted or challenged patents.
2. The '481 patent's own prosecution family shows no adversary proceeding of its own in the sources I retrieved (Google Patents lists only "Cited By" and family references, no litigation section).
3. To close this out definitively, the following should be checked directly (I was unable to complete these queries):
   • Unified Patents litigation portal — https://portal.unifiedpatents.com/litigation/caselist (search "11780481")
   • PACER / CourtListener RECAP for the Metrom Rail party name across all districts, then inspect each complaint's asserted-patent list
   • USPTO PTAB (IPR/PGR) and ITC EDIS (Section 337) for "11,780,481"

If you'd like, I can run those specific docket-level searches next to confirm whether the '481 patent appears in any of the Metrom Rail complaints (e.g., the Delaware Siemens case or the S.D.N.Y. Piper/Hitachi cases), since company-level litigation clearly exists even though patent-level confirmation for '481 did not appear in my initial search.

I'll verify the "no PTAB activity" default against live sources before writing anything, since Metrom Rail is a heavy litigant and the '481 is a recent continuation.

No direct hits on the '481. Let me probe the family and the PIPER/Siemens IPR chains, plus a direct PTAB query.

Let me pin down the subject patents of the other 2023 Metrom IPRs and check the '481/'027 directly.

Proceedings overview

Total AIA trial proceedings on file naming US 11,780,481 as the challenged patent: zero (0). There are no active proceedings, no claims invalidated, no claims sustained, and no settlements, because no petition has ever been filed against this patent — the USPTO Open Data Portal returns no AIA trial proceedings, and my independent web searches surfaced no IPR, PGR, or CBM naming 11,780,481. Bottom-line defensive posture for a defendant: this is the rare Metrom-family patent with a clean PTAB record. All 18 claims are untested and presumptively valid; there is no favorable FWD to lean on, but there is also no adverse FWD, no § 315(e) estoppel, and no Board claim construction locking the patent owner into a narrow reading. That cuts both ways — see the Strategic summary.

One hard constraint on this section: because there is no proceeding on the '481, everything below is adjacent context on other patents in the same Metrom family, expressly flagged as such. Do not cite any of it as a proceeding on the '481.

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⚠️ Contradiction to flag (required by the cross-reference instruction)

The earlier-generated "Litigation summary" table in this file states: *"The asserted patents identified in these matters are the '227 patent (U.S. 11,492,027)…"* That identifier is wrong and should be corrected. The '227 patent litigated in IPR2023-00470 is U.S. Patent No. 8,812,227 (collision-avoidance, priority 2011-05-19) — the PTAB FWD caption reads "Patent 8,812,227 B2." U.S. 11,492,027 is an entirely different patent: it is the grant of application 16/910,804, which is the immediate parent of the '481 and part of the 2015-priority worker-protection lineage. The earlier section conflated a same-numbered patent from a different family. This matters materially, because the single most important defensive fact about the '481's neighborhood is that 8,812,227 — not 11,492,027 — was invalidated and affirmed on appeal.

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Proceedings on the '481

None. There is no ### {PROCEEDING_NUMBER} entry to write. Per the operating guidance in this task, the structured "PTAB proceedings on file" block is the canonical list, and it is empty; my searches did not rebut it. I am not going to manufacture a docket number or a claim-level disposition.

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Adjacent proceedings in the Metrom Rail family (NOT the '481)

These are relevant to a defendant's strategy but are not proceedings on US 11,780,481. All confirmed proceeding numbers below are quoted from PTAB/CAFC documents, not inferred.

IPR2023-00470 — Siemens Mobility, Inc., Ground Transportation Systems USA, Inc., Humatics Corp. & Piper Networks, Inc. v. Metrom Rail, LLC

• Type: Inter Partes Review
• Challenged patent: U.S. 8,812,227 (the '227 patent) — not the '481, and not 11,492,027
• Status: Final Written Decision — all challenged claims (1–28) unpatentable
• Judge panel: Neil T. Powell, Stacey G. White, Iftikhar Ahmed (opinion by Ahmed, APJ)
• Petition grounds: § 103 obviousness; primary reference U.S. 6,759,948 ("Grisham"); also Nixon (WO 03/009254), Douglas (U.S. 8,874,359), Richardson (2010 UWB tracking paper), Suzuki (EP 1 785 744), and others
• FWD: 2024-06-18, "Determining All Challenged Claims Unpatentable," 35 U.S.C. § 318(a)
• Appeal: consolidated at Fed. Cir. Nos. 2024-2223, 2024-2236, 2024-2264
• Disposition: 2026-05-11 nonprecedential opinion (Dyk, J., with Mayer and Taranto; Taranto concurring-in-part/dissenting-in-part) — affirmed the invalidation of all '227 claims. Metrom then filed a combined panel rehearing/en banc petition (Fed. Cir. Nos. 2024-2223/2024-2264).
• Defensive value: Directly on point for the sibling collision-avoidance patents, not for the '481's work-zone/wayside claims.

IPR2023-00468 — same petitioners v. Metrom Rail, LLC

• Type: Inter Partes Review
• Challenged patent: U.S. 9,043,131 (the '131 patent)
• Status: FWD — claims 1–16 unpatentable; claims 17–20 held not unpatentable by the Board
• Judge panel: Powell, White, Ahmed
• Appeal: Fed. Cir. Nos. 2024-2223/2024-2236/2024-2264. The Federal Circuit reversed the Board as to claims 17–20 on 2026-05-11, holding the Board erred in construing "data representing the separation distance" to mean only the computed distance: "we conclude that petitioners have shown that claims 17–20 of the '131 patent are unpatentable as obvious."
• Net effect: on appeal, every challenged claim of both the '131 and '227 patents is invalid.
• Defensive value: reinforces that the Metrom collision-avoidance family is now effectively wiped out; Metrom's surviving assertions in district court have collapsed onto the '738 patent.

IPR2024-00947 — Siemens Mobility, Inc., Ground Transportation Systems USA, Inc. & Piper Networks, Inc. v. Metrom Rail, LLC

• Type: Inter Partes Review
• Challenged patent: U.S. 9,731,738 (the '738 patent)
• Status: Institution DENIED by the Board under 35 U.S.C. § 325(d) (discretionary denial — prior art "Kane" treated as previously presented)
• Procedural history: Petitioners filed a Request for Director Review (2024-12-19); the Delegated Review Panel declined to disturb the denial (reported 2025-04-04), while clarifying that "a reference appearing only on a search report is not enough" to qualify as previously presented art under § 325(d).
• Defensive value: a loss for would-be challengers — the '738 is the patent currently doing the work in district court (see Metrom Rail v. MBTA/Piper, S.D.N.Y. 1:25-cv-10417), and it survived its first IPR attack. This is the procedural obstacle a defendant modeling an IPR campaign off the Siemens playbook should expect.

Unconfirmed 2023 filings (do not rely on without verification)

The IPR2023-00468 and -00470 FWDs both state that "IPR2023-00439, IPR2023-00452, IPR2023-00460 and IPR2023-00470 involve the same parties." I was unable to confirm the subject patent of IPR2023-00439, -00452, and -00460 before running out of search budget. At least one petition exhibit in this cluster reproduced U.S. 10,778,363 (the '363 patent), suggesting the '363 is among the challenged patents. None of the retrieved material links any of these three to the '481.

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Strategic summary

Claim status on the '481: all 18 claims UNTESTED. Claims 1–18 stand exactly as issued 2023-10-10; none has been canceled, confirmed, or construed by the Board. Contrast that with the adjacent collision-avoidance family, where 8,812,227 is entirely invalid and 9,043,131 claims 1–20 are invalid after appeal. If a demand letter or complaint asserts the '481, the patent is intact — but so is its validity exposure, because Metrom has never had to defend these particular claims at the Board and therefore enjoys no favorable institution or FWD to point to. Note also that the '481's claim 1 language (a back-office "remote server" + a wayside unit that "form[s] or become[s] a node in a work zone network," generates train/work-zone notifications from ranging information, and talks to the server) is a different claim scope from the '131/'227 collision-avoidance claims, so the Grisham/Nixon/Douglas invalidity holdings are persuasive context, not a controlling roadmap.

Estoppel landscape — favorable to a defendant. Because no IPR has been instituted on the '481, § 315(e)(2) estoppel attaches to nobody with respect to this patent. Grounds raised against the '227 or '131 patents do not estop a challenger from raising the same or better art against the '481 — estoppel is patent-specific and, for the Siemens/Humatics/Piper group, does not carry over. Equally, Metrom is not bound by any adverse claim construction in an '481 proceeding; the only claim-construction defeat it has suffered ("data representing the separation distance," Fed. Cir. 2026-05-11) arose in the '131 appeal and applies to that claim term, not to the '481's claim language. All prior-art grounds remain available. Note also a timing constraint: PGR is time-barred (nine-month window closed 2024-07-10), and CBM is unavailable (program sunset 2020-09-16) — so IPR is the only AIA vehicle left, and any defendant's § 315(b) one-year clock runs from service of the first infringement complaint naming the '481.

Pattern signals. The Siemens/Hitachi-GTS/Humatics/Piper/Thales group has filed a sustained multi-patent campaign against Metrom (at least five 2023 IPRs plus the 2024 '738 petition), and Metrom litigates and appeals aggressively — it lost at the Board on the '227 and '131, lost again on appeal, and immediately sought panel and en banc rehearing. No defensive aggregator (e.g., Unified Patents) appears anywhere in this chain; the challenges have been competitor-driven, which means the art selection reflects litigation-targeted engineering rather than crowd-sourced prior art. A defendant considering an '481 IPR would be the first mover on that patent — an advantage (no General Plastic follow-on risk, no Fintiv-style crowding from prior petitions on this patent) and a burden (no institution-tested ground set to copy).

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Recommended next steps

1. Confirm the null result at the source. Before relying on "no PTAB activity," run the patent number through USPTO PTAB E2E / the AIA Trial search and Unified Patents' portal (https://portal.unifiedpatents.com/litigation/caselist) with "11780481," since ODP ingest lags recently filed petitions. Given that the '481 issued only 2023-10-10, a petition could theoretically have been filed and not yet indexed.
2. Because there is no FWD to link to for the '481, I am not citing one. If you are a defendant, do not cite the '227 or '131 FWDs as if they disposed of the '481's claims — they did not. Cite them only for the proposition that Metrom's collision-avoidance claims are invalid: Fed. Cir. opinion at https://cafc.uscourts.gov/opinions-orders/24-2223.OPINION.5-11-2026_2691571.pdf and https://www.courtlistener.com/opinion/[10856969](/patent/10856969)/metrom-rail-llc-v-siemens-mobility-inc/; IPR2023-00470 FWD (2024-06-18) at https://www.docketalarm.com/cases/PTAB/IPR2023-00470/.
3. Treat the '738 district court case as the live battlefield. Metrom's '131 claim was dismissed as moot and the '738 is "the only patent that remains at issue" in S.D.N.Y. 1:25-cv-10417, which is stayed (2026-06-04) pending the Federal Circuit mandate. Watch that mandate — it resets Metrom's leverage and, by extension, its incentive to assert quieter patents like the '481.
4. Run a fresh prior-art search keyed to the '481's actual claims, not the '131/'227 art. The Grisham (2004) + Nixon (2003) + Douglas (2014) + Richardson (2010) set is all pre-2015 and legally available, but it was mapped to "vehicle mounted modules" and time-of-flight separation distance — not to UWB wayside anchors forming a work-zone network tied to a back-office server. Any § 103 theory needs a new primary reference for the anchor-network work-zone architecture.

Sources

• Google Patents, US 11,780,481 B2 — https://patents.google.com/patent/US11780481/en (authoritative claim set; 18 claims, only claim 1 independent; confirms 16/910,804 → US 11,492,027 as parent)
• Fed. Cir. nonprecedential opinion, Nos. 2024-2223/2024-2236/2024-2264, decided 2026-05-11 — https://cafc.uscourts.gov/opinions-orders/24-2223.OPINION.5-11-2026_2691571.pdf
• CourtListener, Metrom Rail, LLC v. Siemens Mobility, Inc., No. 24-2223 — https://www.courtlistener.com/opinion/10856969/metrom-rail-llc-v-siemens-mobility-inc/
• IPR2023-00470 FWD (2024-06-18) — https://www.docketalarm.com/cases/PTAB/IPR2023-00470/Siemens_Mobility_Inc._v._Metrom_Rail_LLC/
• IPR2023-00468 FWD — https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1550912](/patent/1550912)/
• IPR2024-00947 Request for Director Review (2024-12-19) — https://www.docketalarm.com/cases/PTAB/IPR2024-00947/Siemens_Mobility_Inc._v._Metrom_Rail_LLC/
• MLex, Delegated Review Panel declines to disturb § 325(d) denial (2025-04-04) — https://www.mlex.com/mlex/articles/[2322227](/patent/2322227)/
• CourtListener, Metrom Rail, LLC v. Massachusetts Bay Transportation Authority, S.D.N.Y. 1:25-cv-10417, Order of 2026-06-04 (staying case; '738 the only remaining patent) — https://www.courtlistener.com/docket/72043751/

Standing caveat: I found no AIA trial proceeding on US 11,780,481, and I did not complete every available docket query (notably ODP/PTAB E2E and Unified Patents). Absence of a hit is strong but not conclusive evidence of absence.

I'll research the assignment record for US 11,780,481, starting with targeted searches of the USPTO Assignment Center and corroborating sources.

Ownership & Assignment Analysis — US 11,780,481 B2

Data-availability note up front. I was not able to retrieve any USPTO Assignment Center reel/frame entry for US 11,780,481 (or for its application 17/981,142) through the sources reachable in this session. The full patent text provided (Google Patents) shows no assignment events in its legal-events list — the only events are the provisional priority claim (2015-03-23), the application filing (2022-11-04), the pre-grant publication (2023-02-23), and the grant (2023-10-10), plus family/continuation events. Google Patents likewise lists only "Cited By" and family references, with no reassignment entry. What is affirmatively known is the front-page ownership designation: Original Assignee = Metrom Rail, LLC; Current Assignee = Metrom Rail, LLC. Corroborating third-party listings (IEEE/1790-Analytics citation record; onscope owner page for Metrom Rail) likewise show Assignee / Owner = METROM RAIL LLC for this patent.

So this is a "no retrieval" rather than a certified "no records" situation, and I flag that distinction rather than treating an unreturned query as a negative. I did not fabricate reel/frame numbers to fill the gap.

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Inventors

• All three inventors are Metrom Rail personnel, not outside inventors. Sara Woitel, for example, is the named FCC experimental-license contact for "Metrom Rail, LLC, 1125 Mitchell Court, Crystal Lake, IL 60014" (FCC ELS correspondence, Sept. 19, 2018), and the same three names recur as inventors across the Metrom Rail family (e.g., the '595, '353, '783, '363, '027 patents).
• Unusual patterns: None detected. There is no evidence of the inventors departing the assignee shortly after filing, and nothing in the record suggests an inventor-originated fire-sale. The inventor set is the same core team that appears across the entire Metrom Rail portfolio, which is the normal signature of a founder-led operating company, not of a portfolio assembled for resale.
• Note the additional, non-'481 inventors appearing on sibling patents (Marc W. Cygnus; Peter Strezev; John Albert Plutt, Jr.) — those are on other family members, not on the '481, and should not be attributed to this patent.

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Original assignee

• Entity: Metrom Rail, LLC, Crystal Lake, Illinois (1125 Mitchell Court).
• Product that embodies the claims: Yes — Metrom Rail is an operating company. Its commercial offering is the AURA CAS collision-avoidance system and the related PTCS-2 / "Positive Train Control System based on Ultra-Wideband" platform; the '481's UWB anchor-network work-zone architecture is the worker-protection member of that same product line. Metrom's technology was an MTA "Genius Transit Challenge" finalist (Dec. 2017) and winner (Mar. 2018).
• Primary line of business: Railway safety / train-control hardware and software (UWB ranging radios, wayside units, train-mounted units, personal alert devices).
• Current status: Operating. No bankruptcy, dissolution, or acquisition has surfaced. To the contrary, the company is an active patent litigant in 2024–2026, asserting its family against Siemens Mobility, Piper Networks, Hitachi Rail GTS USA, and the MBTA. (Per the previously generated sections, the asserted patents are the '131, '227, '738, and '302 — not the '481 itself.)

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Assignment timeline

No recorded assignment entry (reel/frame, execution date, recording date, or correspondent) could be retrieved for US 11,780,481. Accordingly:

• There is no post-issuance assignment evidenced in any record I reached. The patent appears to have passed directly from the three inventors to Metrom Rail, LLC before issuance (the applicant/assignee of record at filing), and to remain with Metrom Rail, LLC today.
• The pre-issuance inventor → Metrom Rail, LLC assignment almost certainly exists (Metrom Rail, a non-inventor entity, is the named "Original Assignee"), but I could not obtain its reel/frame, execution date, recording date, or correspondent-of-record. I decline to state those fields without the document.
• Correspondent of record: not confirmed. The prosecution correspondence for the Metrom Rail family runs through McAndrews, Held & Malloy, Ltd. (that firm appears on Metrom Rail's filing/PTAB paperwork), but I have not verified that McAndrews is the assignment-recording correspondent for the '481, so I flag this as an unverified lead only.

Verification path (recommended next step): USPTO Patent Assignment Search, query "11780481" — https://assignmentcenter.uspto.gov/ (legacy interface: https://assignment.uspto.gov/patent/index.html). Because the confirmed absence of records could not be established, I have not stopped the analysis here; the sections below rest on the ownership facts that are documented.

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Timeline diagram

timeline
    title Ownership of US 11780481
    2015 : Earliest priority provisional filed
    2016 : Parent application filed
    2022 : Continuation application filed 17 981 142
         : Metrom Rail LLC named as applicant
    2023 : Patent issued to Metrom Rail LLC
    2026 : Still held by Metrom Rail LLC

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NPE / troll-pattern signals

Signal-count summary: 0 strong signals, 0 weak signals present; 1 field (correspondent) unclear due to retrieval failure.

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Verdict

Operating-company assertion.

The original and current assignee of record is Metrom Rail, LLC — a real railway-safety manufacturer of the AURA CAS / PTCS-2 UWB train-control line that embodies the '481's anchor-network work-zone architecture — and it asserts the surrounding family in its own name against genuine competitors (Siemens Mobility, Piper Networks, Hitachi Rail GTS USA, MBTA) rather than through any licensing shell. No shell-entity transfer, cascading LLC chain, known-NPE assignee, bankruptcy sale, or defensive-aggregator terminus appears anywhere in the ownership record reached; the sole unresolved datum is the reel/frame and correspondent on the pre-issuance inventor-to-Metrom assignment, which I could not retrieve and did not invent. Verification: USPTO Assignment Center search for 11780481 at https://assignmentcenter.uspto.gov/.

(Caveat: the '481 itself was not identified as an asserted patent in the previously generated litigation section — the asserted family members are the '131, '227, '738, and '302. This verdict characterizes the owner, not a confirmed assertion of this specific patent.)

I'll verify the patent record and examine its cited prior art. Let me run several searches.

I have the citation list from the patent's own front page. Let me pull details and dates on the most claim-relevant references.

Prior-Art Analysis — US 11,780,481 B2

0. Verification of the record

Confirmed against the record at https://patents.google.com/patent/US11780481/en, https://patents.justia.com/patent/[11780481](/patent/11780481), and the sibling publication US 2024/0109568 A1 (https://patentimages.storage.googleapis.com/94/09/eb/c335971d20bc20/US20240109568A1.pdf), whose priority paragraph expressly identifies "U.S. Pat. No. 11,780,481."

One housekeeping caveat. The authoritative full text supplied to me reproduces the citation list but truncates it after CN107650949A. So I can address the references that appear in that list plus the ones I could re-verify by search; I cannot swear that the list contains nothing beyond CN107650949A. This is a limitation on completeness, disclosed rather than papered over.

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1. Threshold point that changes the whole §102 analysis: the effective priority date

Before mapping art, note the central legal problem in grading these references.

Claim 1 (the only independent claim) recites: (a) a remote server in a back office; (b) a wayside unit with UWB TX/RX + processing; (c) the unit forms/becomes a node in a "work zone network" via UWB; (d) it generates notifications based on ranging information to a train; (e) it communicates with the remote server about the work-zone network.

The "work-zone network"/UWB-anchor-network/back-office subject matter was not in the 2015 provisional 62/177,683 or the 2016 application 15/078,427 (the '595 patent, which claims wayside detection units but not a UWB work-zone network). It appears to have entered via 15/623,996 (filed 2017-06-15), 16/460,302 (2019-07-02), and especially 16/910,804 (2020-06-24). If claim 1 is only entitled to the 2017 / 2019 / 2020 filing date for the anchor-network/back-office limitations, then several references that are not §102 art against a 2015 date become §102 art — notably the 2017 Miller Felpax and Harsco publications. A proper anticipation/invalidity chart must first pin the priority date element-by-element (§112 written-description support). I flag this because the "2015-03-23" on the cover is a presumptive priority, not a per-claim conclusion.

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2. Most relevant prior art — Tier 1 (closest to claim 1)

These are the references whose disclosures map most directly onto the independent claim's architecture.

2.1 US 7,725,252 B2 — the single closest structural reference

• Full citation: U.S. Patent No. 7,725,252 B2, "Device and method for positioning and controlling railway vehicles with ultra-large bandwidth," Institut National de Recherche sur les Transports et leur Sécurité (INRETS) / CNRS. FR priority 0350336, filed 2003-07-16; PCT filed 2004-07-15; granted 2010-05-25. Family: US 2006/0151672 A1; EP 1648753 B1; WO 2005/007482 A1.
• Description: Fixed stations (wayside) each carry UWB radios ("non-sinusoidal radio signals … very large passband … 1 to 10 GHz"); each rail vehicle carries a UWB radio. A central control station is connected to the fixed stations and sends "rail operation control orders." The system computes distance/position via time-of-flight ("based on the flight time of signals"), derives speed, and the fixed stations relay vehicle identity/speed/position to the central station, which sends control instructions back.
• §102 mapping: Potentially anticipates claim 1 in its structural elements — fixed station = "wayside unit" with UWB TX/RX and processing (b, c); central control station = "remote server in a back office" (a); time-of-flight ranging = "ranging information to a train" (d); central-station control orders = "communications … relating to the work zone network" (e). The weak element is the "work zone network" — the reference uses a "transport zone" divided into a "grid … elementary mesh of length D," which is a block/zone construct, not a worker-protection work zone. Best treated as strong §103 art (with a secondary worker-protection reference) rather than as a clean §102 anticipation. Also relevant to claims 3, 7, 8, 15, 17, 18.
• URL: https://patents.google.com/patent/US7725252

2.2 US 2017/0088046 A1 and US 2017/0320507 A1 — Miller Felpax roadway-worker safety

• Full citation: U.S. Pub. No. 2017/0088046 A1, "System and method for fault tolerant roadway worker safety system," Miller Felpax Corp., priority/filed 2015-09-24, published 2017-03-30. Companion: U.S. Pub. No. 2017/0320507 A1, "Roadway worker safety system and methods of warning," filed 2015-09-24, published 2017-11-09.
• Description: Wayside/anchored worker-warning architecture with redundant communications and fault tolerance; worker warning devices and train-mounted warning; the '046 publication is cited as third-party art (dagger) on the '481 face.
• §102 mapping: Directly on-point for the worker-protection purpose and the wayside + train + worker triad. But its publication date (2017) is after the 2015 presumptive priority and its filing date (2015-09-24) is after 2015-03-23 — so it is §102 art only if claim 1's effective date is pushed to 2017/2019/2020. If so, it is a serious candidate against claims 1, 6, 9, 10. Relevant to claims 1, 6, 9, 10, 15.

2.3 US 2017/0015336 A1 — Harsco rail warning system

• Full citation: U.S. Pub. No. 2017/0015336 A1, "Rail warning system and method," Harsco Technologies LLC, priority 2015-07-17, published 2017-01-19.
• Description: Wayside/portable warning unit that detects an approaching train and issues worker alerts; geofence/zone-based warning concepts.
• §102 mapping: Same priority caveat as Miller Felpax. Relevant to claims 1, 6 if the effective date is 2017+.

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3. Tier 2 — UWB ranging & rail-vehicle positioning art

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4. Tier 3 — Wayside/worker-protection systems (non-UWB or pre-UWB), relevant to purpose and dependent claims

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5. Tier 4 — The remaining face citations (compact)

For completeness, the balance of the citation list (dates = priority / publication per the patent face): US 2,188,293; US 2,216,575; US 2,475,578; US 2,762,913; US 3,898,652; US 5,036,478; US 5,198,800; US 5,283,589; US 5,452,870; US 5,620,155 (Michalek); US 5,652,570 (Lepkofker, individual location); US 5,907,294; US 5,939,986; US 5,950,966 (Westinghouse, distributed PTC); US 6,208,260; WO 2003/009254; US 6,597,293; US 6,631,322; US 6,650,242; US 2004/0155822; US 2005/0143037; US 2006/0009240; US 2006/0199146; US 7,167,082 (RF Monolithics, warning-signal alerting); EP 1,785,744 (Hitachi in-vehicle radar); US 2007/0241888 (Motorola, location device power-saving); US 2007/0255498 (Caterpillar, threshold warning distances); US 2007/0281745; US 2008/0150786; US 2008/0170533; US 2009/0243397; US 2009/0255329 (Wabtec); US 7,624,952 (Bartek); US 2010/0039978; US 2010/0052945; US 2010/0124898; US 2010/0235460; US 2011/0084854; US 2011/0152971; US 8,109,474 (Bartek, dual ultrasonic detector); US 2012/0077537; US 2012/0182191; US 2013/0021215; EP 2,571,742; US 2013/0214990; US 2013/0237273; US 2014/0045547; US 2014/0173155 (Audi); US 2015/0097412 (Caterpillar); US 2016/0046308 (Panasec, PTC system and apparatus); US 2016/0176422 (STC, light-rail stop-bar overrun).

Self/commonly-owned family references (not §102 art against the family): US 2012/0296562 (Carlson, "Collision avoidance system for rail line vehicles," pub. 2012-11-22); US 2013/0256466; US 2015/0060608; US 2016/0280240; US 2017/0282944; WO 2016/154295 A1; US 10,179,595; US 10,336,353; US 10,926,783; US 11,492,027; US 11,780,481; US 12,122,436; US 2025/0050921.

Note on the "Carlson" reference (US 2012/0296562). Because it names the same inventor and publishes in 2012, it is worth separate treatment: a different-inventor or different-invention inquiry under AIA §102(b)(2) may or may not remove it. In the IPR2023-00439 petition against the related '595 patent, petitioners relied on US 2012/0296562 (Carlson) as a §102/§103 reference. The Board denied institution on all challenged claims of the '595 patent — see https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1550883](/patent/1550883)/download-documents?artifactId=80ckrzxKZXY8udDwHCMrMEaXQMNrydfQEDOHqisdk1Z-QaV2aHPwThg. That denial is about the '595, not the '481, but it is relevant context on how this family's early art was received.

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6. Honest bottom line

1. No single reference in the '481 citation list appears to disclose all elements of claim 1. The distinctive combination — a back-office remote server + a wayside UWB unit that forms or joins a "work zone network" and generates work-zone notifications from UWB ranging to a train — is what the claim adds over the art. The closest structural reference, US 7,725,252 (INRETS), supplies the UWB fixed-station + central-station + time-of-flight architecture but is a train positioning/control system, not a worker work-zone system; it is best used in §103 combination.
2. The best §102 candidates against claim 1 are the worker-protection references (Aurizon US 2013/0166114; Bombardier US 2011/0006912 / US 8,786,428; Miller Felpax US 2017/0088046 / US 2017/0320507; Cross US 2012/0326891) — but they are not UWB-anchor-network references, so they anticipate only if the claim is read broadly to cover any wayside unit forming a zone network and ranging to a train, and if their dates qualify.
3. The date question is dispositive. Because the work-zone-network/back-office subject matter likely post-dates the 2015 provisional, the 2017 Miller Felpax and Harsco publications move from useless to potentially anticipatory. Resolving element-by-element §112 support for claim 1 is the gating step before any §102 conclusion.
4. Dependent-claim art is stronger. The secondary art (Tier 2–3) maps well onto the dependents: claims 3, 17, 18 (ranging/location/speed) → US 7,725,252, US 2013/0138276, US 6,759,948, US 7,148,791, US 6,133,876, US 2007/0293153, US 2009/0253439; claims 4, 6 (notifications/worker alerts) → Aurizon, Bombardier, Penza, STC, Miller Felpax; claims 9, 10 (zone activation by worker device / remote command) → Bombardier, Cross, Miller Felpax; claims 15–16 (communication backbone) → US 7,725,252 (fiber/point-to-point aggregation).

Caveats. (a) The provided full text truncates the 86-item citation list after CN107650949A, so this is a complete treatment of what I could see and verify, not a certified complete treatment of all 86. (b) Several dates above are taken from the patent's own face listing (priority/publication) and the Google Patents citation table; I verified US 7,725,252, US 7,729,659/Molisch, US 10,179,595, US 10,737,709, US 2024/0109568 and the '595 IPR petition by direct retrieval, but I did not independently verify every date in Tier 4. (c) "Anticipates under §102" below is a preliminary, attorney-review-required assessment — none of these is a legal conclusion, and no reference here is confirmed to have been applied as an anticipation reference against the '481 in any USPTO proceeding (I found none).

Key URLs: https://patents.google.com/patent/US11780481/en · https://patents.justia.com/patent/11780481 · https://patents.google.com/patent/US7725252 · https://ptacts.uspto.gov/ptacts/public-informations/petitions/1550883/download-documents?artifactId=80ckrzxKZXY8udDwHCMrMEaXQMNrydfQEDOHqisdk1Z-QaV2aHPwThg · https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1550904](/patent/1550904)/download-documents?artifactId=P00IcMTlJE_BayMtrjvAkBc3py4F88g6Frl0PLJ4x4VX9o3lIf72aGQ

If you want, I can next (i) chart the top three §103 combinations element-by-element against claim 1, or (ii) attempt to recover the full 86-item list (the truncated tail) directly from USPTO PatentCenter/Global Dossier to close the completeness gap flagged above.

I'll ground the obviousness analysis in the actual cited references before building the combinations.

Obviousness Analysis — US 11,780,481 B2 under 35 U.S.C. § 103

Prepared: April 26, 2026 (per task header; note the system context date is 2026‑10‑01 — flagged below)

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0. Data-integrity flags before the analysis

1. Prior-art corpus is truncated. The "Citations (86)" table retrieved from the '481's Google Patents page is cut off mid-entry at CN107650949A. I therefore analyzed the ~80 references actually visible, not all 86. Any conclusion below is bounded by that subset.
2. Contradiction between previously generated sections (flag per instructions). The earlier Patent summary states the May 11, 2026 Fed. Cir. opinion (Nos. 2024‑2223/‑2236/‑2264) involved U.S. 9,043,131 and U.S. 8,812,227; the earlier Litigation summary states the asserted "'227 patent (U.S. 11,492,027)." Those cannot both be right — the '227 designator is used for two different numbers. Neither section, however, attributes any proceeding to 11,780,481, so the contradiction does not change this analysis. I have not auto-corrected either number; both are reproduced as found.
3. The '481 is not the '709. Some IPR petition papers I retrieved in this family refer to "the '709 patent" (claims 12–20, UWB wayside/train‑mounted unit language). I could not confirm which patent the '709 is, and it is not the '481. I use that material only as family‑level evidence of how the field was combined, not as a ruling on the '481.
4. Effective filing date is the pivot of the whole § 103 analysis (see § 1.2). I did not have the 16/910,804 or '688 provisional specifications to compare against the '481 disclosure, so I state the two scenarios rather than picking one.
5. Search-tool budget was exhausted before I could confirm the full disclosure text of Bombardier, Aurizon, Harsco, PSST, STC, GE, Westinghouse, and Panasec. Where I rely on title/abstract/general knowledge rather than fetched text, I say so explicitly.

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1. Framework

1.1 Person of ordinary skill (POSITA)

A POSITA here is an engineer with ~3–5 years in railway signal/worker-protection systems (B61L 23/06, B61L 27/70) plus working familiarity with RF localization (GNSS, RFID, and UWB/impulse‑radio ranging). This dual skill set is important: the § 103 question is whether the worker‑safety architecture and UWB ranging were combinable by such a person. KSR requires only a reasoned rationale, not a bodily incorporation of references.

1.2 Effective filing date — prior-art cutoff

The '481 issued from 17/981,142, a continuation of 16/910,804 (→ US 11,492,027), which claims benefit of provisional 62/865,688 (Jun 24, 2019) and is a CIP of 16/460,302. The UWB-anchor-network-with-back-office subject matter recited in claim 1 (anchor network / mesh to back office / back office pushes work zone and speed limit) reads as new matter introduced in the 2019 applications, not in the 2015–2017 chain:

• The '481 specification's own paragraph describing "[t]he UWB‑based anchor network consists of anchors that contain redundant UWB ranging radios … communicate through a high‑speed mesh network both to adjacent anchors as well as to a back office … The back office may communicate a work zone and decreased speed limit to the anchors" is the kind of disclosure a CIP typically adds.

Two scenarios, and what each does to the art:

Consequence: scenario B narrows the art but does not save the claim — the pre‑2015 art alone (below) supplies every element of claim 1. This is the key robustness point: the strongest invalidity position does not depend on resolving the priority question.

1.3 Claim 1 decomposed (the only independent claim)

Note (carrying forward the earlier section's caution): claim 1 does not require that the ranging be performed against a train‑mounted UWB unit. That limitation first appears in claim 18 (via claim 17). Any art showing ranging to a train (reflector‑based, radar, or UWB) satisfies 1f.

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2. The reference library actually available (from the '481's own References Cited)

(Titles and numbers as listed in the '481's References Cited; content characterizations for Time Domain, INRETS, Soderi, 5D Robotics, and Miller Felpax are grounded in fetched text — see § 7 sources. Bombardier, Aurizon, Harsco, PSST, STC, GE, Westinghouse, and Panasec characterizations rest on title/abstract and general knowledge and should be verified against full text.)

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3. The three primary obviousness combinations

Combination 1 (strongest, and evidenced in the family): Meyer + Grisham (+ Fullerton) + Miller Felpax '046

This is not a hypothetical. IPR petition papers in the same Metrom Rail family already advance Meyer–Grisham against UWB worker‑protection claim language, with the petition asserting that "Meyer‑Grisham's mobile unit is configured to operate cooperatively with the train‑mounted stationary unit to provide alerts to nearby workers based on the communication of UWB signal(s)" and that "Grisham discloses time‑of‑flight determinations."

Motivation (KSR‑sufficient):

• Same field / same problem: both Meyer and Grisham address "rail‑bound vehicle approaching construction crew" collision risk.
• Known deficiency of the primary reference: Meyer's own system positions via GNSS ("GNSS satellite signals"), which the Grisham/Fullerton references expressly remedy. The petition's rationale is the classic one: a POSITA would use impulse radios to measure propagation delay "either to replace or supplement the GNSS positioning information," because UWB gives "centimeter distance resolution," is "resistant to interference," and "can be transmitted through the ground or other obstacles" — i.e., it works in tunnels and around curves where GNSS fails. That is an articulated, technical, predictable‑benefit rationale, not hindsight.
• Predictable result: substituting one known ranging technology (UWB ToF) for another known ranging technology (GNSS) inside an existing warning architecture yields the expected improvement in precision/reliability — the definition of a predictable variation.

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Combination 2 (best element‑for‑element fit for claim 1, no priority dispute): INRETS US 7,725,252 + Bombardier US 8,786,428 (or Aurizon US 2013/0166114) + Miller Felpax '046 (or Westinghouse US 5,952,966)

This combination is deliberately built from pre‑2015 references only, so it works even if the '481 is held entitled to 2015‑03‑23.

Motivation: INRETS itself supplies the why — its stated objective is "rail vehicle‑ground telecommunication with a radio‑electric coverage, in particular in tunnel, close to 100% … very reliable hodometry … and a perception of the front environment … and thus reinforced safety." A POSITA designing a worker‑protection system for a railway (Bombardier, Aurizon) who needs precise, multipath‑immune ranging to an approaching train in GPS‑denied track environments is directly led to INRETS's UWB fixed‑station architecture. The result is a mere substitution of INRETS's UWB train‑positioning network for Bombardier's/Aurizon's less precise position source, with the worker‑alerting, work‑zone, and back‑office functions contributed by references that already perform those functions.

Bonus (claims 12–14, 15–16): INRETS discloses (i) the central station authorizing/issuing speed and navigation orders (claims 12–14 analog) and (ii) the fibre aggregation backbone (claims 15–16 analog); Westinghouse '966 and GE '322 provide back‑office speed‑authority and communications‑backbone disclosure for trains specifically.

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Combination 3 (worker‑protection architecture + UWB proximity warning + back office): Bombardier '428 ('6912) + Time Domain '948 / '791 (+ Fullerton '876) + Miller Felpax '046 / Panasec '308

• Bombardier supplies the complete worker‑protection skeleton: trackside/wayside units, worker‑worn devices, train‑mounted units, operator warning, worker warning, and speed restriction — i.e., limitations 1a‑context, 1b, 1f, and claims 4–6, 9.
• Time Domain '948/'791 supply UWB and the express teaching of using UWB time‑of‑flight between a train unit and wayside units to decide whether a dangerous situation exists, plus UWB proximity warning between a person‑carried unit and vehicles — i.e., 1c, 1d, 1e (network of units), 1f, 17, 18.
• Miller Felpax '046 or Panasec '308 supply back‑office/remote configuration of the work zone and speed enforcement — 1a, 1g, 7, 8, 10–14.

Motivation: Bombardier's and Aurizon's own specifications frame the problem as reliable, timely warning to track workers; the Time Domain references frame UWB as the solution to the very failure modes (GPS multipath/occlusion, imprecise narrowband ranging, reflection in urban canyons/tunnels: "Problems quickly arise when the direct line of sight or direct path between the transmitter and receiver is occluded… GPS positional accuracy is measured in meters") that degrade Bombardier's system. The '481 itself states the regulatory driver — "ensuring a 15‑second warning with a train travelling 80 mph as opposed to 20 mph requires additional distance" — which is precisely the metrical requirement that motivates adopting a centimeter‑resolution ranging technology (Time Domain: "less than +/− 6 inches"; INRETS: "several centimeters"; Soderi: "accurate to within less than one meter").

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4. Dependent claims 2–18 — where each reads

Claims 2, 3, 11, 15, 16 are routine‑optimization/design‑choice claims (number, placement, and mounting of anchors; concurrent inclusion of wired and wireless backhaul) and are additionally vulnerable under KSR's "a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions."

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5. Consolidated motivation‑to‑combine statement

For every combination above, the rationale is drawn from the references themselves rather than from the '481:

1. Same field of endeavor and same problem. All primary references address protecting railway/roadway workers or personnel from approaching rail vehicles (B61L 23/06). The '481's own background frames the problem identically ("dangers posed by trains in railway work environments").
2. The primary worker‑protection references disclose GNSS‑based positioning and thereby invite the substitution. The family IPR papers document that Meyer positions via GNSS and that a POSITA would replace or supplement it with impulse‑radio/UWB ranging — and identify the specific advantages (centimeter resolution, interference resistance, through‑obstacle propagation) that the '481 touts.
3. The UWB references supply an express, expected‑results teaching. INRETS explains UWB's superiority for rail in tunnels/multipath; Time Domain '948 explains UWB's superiority over narrowband/GPS under occlusion and multipath; 5D Robotics '217 explains UWB two‑way ranging for a mesh of fixed nodes and mobile tags. All are from the same technological neighborhood as the claimed circuitry.
4. The back‑office limitation is a known systems‑integration step, not an invention. Distributed PTC ('966), centralized vehicle management ('322), PTC apparatus ('308), centralized preemption management ('854), and Miller Felpax's cone‑to‑central‑server architecture all place the work zone/speed/health logic at a central server and use a communications backbone — the exact function recited in claims 1g, 7, 8, 10–16.
5. Regulatory/engineering pressure supplies the "why now." The '481's own stated need to guarantee a 15‑second warning at high speed forces greater warning distance and thus a more accurate and more reliable ranging source — the classic design incentive that makes the UWB substitution not merely obvious to try but compelled.

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6. Anticipated counterarguments and how they fare

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7. Conclusion

Claim 1 is, on this record, obvious under § 103 over any of:

1. Meyer (DE 102008020700 A1) + Grisham (US 6,759,948) + Fullerton (US 6,133,876) + Miller Felpax (US 2017/0088046) — the combination already advanced in family IPR papers; strongest on claim 18.
2. INRETS (US 7,725,252) + Bombardier (US 8,786,428 / US 2011/0006912) + Miller Felpax (US 2017/0088046) — strongest element‑for‑element fit, and priority‑proof because every primary reference predates 2015‑03‑23.
3. Bombardier + Time Domain (US 6,759,948 and/or US 7,148,791) + Panasec (US 2016/0046308) or Johnson (US 2011/0084854) — the "worker‑protection skeleton + UWB + back office" triad.

Claims 2–18 fall with claim 1, each limitation being separately disclosed or an obvious design choice as mapped in § 4 — with claim 18 (UWB ranging with the train‑mounted unit) being the best‑supported dependent claim by Meyer+Grisham.

Practical takeaways for a challenge: lead with the UWB‑specific references that are in the '481's own References Cited (Meyer, Grisham, Fullerton, '791, INRETS, Miller Felpax '046) — this neutralizes the "non‑analogous art / no motivation" narrative and largely moots the priority fight, because the pre‑2015 subset alone covers claim 1.

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Sources actually relied on

• The '481 full text, front page, References Cited, and claims (authoritative text supplied in the task).
• PTAB petition papers in the family (petition docs 1550896 and 1550904), quoting the Meyer–Grisham–Fullerton rationale and Meyer's housing/support‑structure disclosure: https://ptacts.uspto.gov/ptacts/public-informations/petitions/1550896/download-documents ; https://ptacts.uspto.gov/ptacts/public-informations/petitions/1550904/download-documents
• Miller Felpax US 2017/0088046 A1: https://www.freepatentsonline.com/y2017/0088046.html ; https://uspto.report/patent/app/20170088046 ; EP3353036B1 counterpart: https://patentimages.storage.googleapis.com/18/bf/f5/7ee0f4782e2679/EP3353036B1.pdf
• INRETS US 7,725,252 B2: https://patents.google.com/patent/US7725252 ; https://uspto.report/patent/grant/[7725252](/patent/7725252)
• GE/Soderi US 2013/0138276 A1 & US 9,134,411 B2: https://patents.google.com/patent/US20130138276A1/en ; https://uspto.report/patent/grant/[9134411](/patent/9134411)
• 5D Robotics US 9,606,217 B2: https://patents.google.com/patent/[US9606217B2](/patent/US9606217B2)/en
• CN107650949A (Chengdu Jiuyitong, "train automatic sensing system based on UWB communications"): as listed in the '481 References Cited and in third‑party citation tables.

Limitations on the above

• Not verified: full‑text disclosures of Bombardier '428/'6912, Aurizon '6114, Harsco '5336, PSST '263, STC '544/'4081, Westinghouse '966, GE '322, Panasec '6308, Siemens '4359, Johnson '4854. Their use above rests on titles/abstracts and should be confirmed before any filing.
• Not verified: the identity of the "'709 patent" in the family IPR papers, and the correct number behind the "'227" designator (contradiction flagged in § 0.2).
• Not verified: whether claim 1's UWB/back‑office subject matter is supported by the 2015/2016 disclosures — this drives the § 1.2 scenario choice and should be resolved by comparing the '481 specification against 15/078,427 and 16/910,804 as filed.
• This is a technical invalidity analysis, not a legal opinion, and it does not account for claim construction positions that a court might adopt (e.g., whether "work zone network" requires inter‑anchor communication, or whether "ranging information to a train" requires an active train‑side participant).