US 9731738

I'll search for the specific patent number and check for any 2026 litigation activity.

Let me verify the independent claim set of the '738 patent specifically and check for any 2026 CAFC docket tied to that number.

US Patent 9,731,738 — Verified Summary

Identification (as issued):

• Patent number: US 9,731,738 B2 (not to be confused with related Metrom-family numbers such as 9,043,131 or 8,812,227)
• Title: "Rail vehicle signal enforcement and separation control"
• Application: US 14/809,950; filed July 27, 2015
• Granted/issued: August 15, 2017
• Priority date (listed): September 3, 2013 (Google Patents lists 2013-09-03; a related family publication, US 2015/0060608 A1, lists 2013-09-02 — flagged as a discrepancy in the records, not corrected here)
• Anticipated expiration (record): 2034-09-03
• Assignee: Metrom Rail, LLC (original and current assignee per the record; Google notes assignee listings are not legally certified)
• Inventors: Richard C. Carlson, Kurt A. Gunther, Marc W. Cygnus
• Pre-grant publication: US 2015/0329130 A1
• Status: Active

Product family/litigation identifier: family ID 52581772. Sources: https://patents.google.com/patent/US9731738/en ; https://insight.rpxcorp.com/patent/[US9731738B2](/patent/US9731738B2)

Abstract (as published)

"A system for vehicle management includes a control signal interface subsystem and a vehicle-mounted subsystem. Each of these subsystems includes an ultra-wideband (UWB) communications component. The subsystems communicate with each other through the UWB components. The vehicle mounted subsystem interfaces with a braking system of the vehicle. The vehicle mounted subsystem determines the distance between it and the control signal interface subsystem based on the time-of-flight of at least one communication between the subsystems. The vehicle-mounted subsystem can cause the braking system of the vehicle to activate if the distance between the vehicle-mounted subsystem and the control signal interface subsystem is less than a threshold."

Note the abstract is framed around a "system for vehicle management," while the granted claim 1 is framed as "a system for evaluating vehicle operation compliance" — the abstract and claim 1 are not textually identical.

Independent Claims — Plain Language

The patent has claims 1–18 (all 18 were challenged in IPR2024-00947). I can state claim 1 with high confidence because it is reproduced in the PTAB petition/denial record. For the remaining independent claims I have lower confidence and flag it below.

Claim 1 — "System for evaluating vehicle operation compliance" (verified text)

• A control signal interface subsystem plus a vehicle‑mounted subsystem.
• The vehicle‑mounted subsystem is configured to:
  • communicate with the control signal interface subsystem to receive information about the status of a control signal;
  • determine a rule for vehicle behavior based on that status; and
  • observe the vehicle's operation to evaluate compliance with the rule.
• Both subsystems contain an ultra‑wideband (UWB) communications component.
• The two subsystems are further configured to communicate UWB signals carrying data pertinent to evaluating compliance, where the data comprises at least one of: a unique ID of the vehicle‑mounted subsystem, a signal indication, a track number, a track direction, speed, and direction of travel.

Source: IPR2024-00947 petition excerpt (https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1556106](/patent/1556106)/download-documents) and RPX claim listing (https://insight.rpxcorp.com/patent/US9731738B2).

Other independent claims — uncertainty flagged. The specification describes several distinct inventive groupings that likely map to other independent claims, but I do not have authoritative granted-claim text for them:

1. A "system for vehicle management" with a UWB control‑signal‑interface subsystem and a UWB vehicle‑mounted subsystem that interfaces with the vehicle's braking system and determines distance by time‑of‑flight, optionally alerting/braking below a threshold (this is the claim set of the related publication US 2015/0060608 A1, claims 1 and 7 — those claims are not necessarily coextensive with the '738 patent's later continuation claims).
2. A vehicle‑mounted system interfacing with a brake loop — a switch bridging the brake loop, with a processor that automatically determines a braking event without operator‑actuator status input, opens the switch to interrupt the loop, and closes it at expiration, optionally with an alert.
3. A system for vehicle speed management in which the vehicle‑mounted subsystem receives control‑signal status, determines a rule (e.g., red/double red/yellow/double yellow, stop‑time duration, speed or maximum speed after stop‑time expiration), and evaluates compliance.

I would verify the exact wording and count of independent claims against the USPTO PatentCenter/issued-claim text before relying on items 2–3 as claim language.

Plain-Language Overview of the Technology

The '738 patent is an overlay safety system for (e.g., light‑rail/commuter) trains that are still manually operated. Wayside signal control interface subsystems and vehicle‑mounted subsystems each carry UWB radios, form a peer‑to‑peer network, and exchange data (unique ID, signal indication, track number/direction, speed, direction of travel). Using time‑of‑flight, the vehicle computes its distance to a signal or another vehicle and, when speed/distance/conditions cross a threshold, alerts the operator and can automatically actuate the brakes (via interrupting the vehicle's brake loop), while the vehicle autonomously determines rules for behavior from control‑signal status and evaluates compliance. It also uses RFID tags along the track, GPS, and wheel‑speed sensing as redundant/backup location and speed sources — including where GPS is unavailable (tunnels/subways).

2026 CAFC Docket and Litigation — Important Distinction

• No 2026 Federal Circuit appeal specific to US 9,731,738 was found. The May 11, 2026 Federal Circuit nonprecedential decision Metrom Rail, LLC v. Siemens Mobility, Inc., Nos. 2024‑2223/2024‑2236/2024‑2264 (oral argument Apr. 13, 2026), concerns U.S. Patent Nos. 9,043,131 and 8,812,227 — not the '738 patent. That appeal affirmed unpatentability of all '227 claims and claims 1–16 of the '131 patent and reversed as to claims 17–20 of the '131 patent (construing "data representing the separation distance"). Sources: https://www.cafc.uscourts.gov/2026/05/11/page/2/ ; https://fedcircuitblog.com/2026/05/12/opinions-orders-may-12-2026/ ; https://law.justia.com/cases/federal/appellate-courts/cafc/24-2223/24-2223-2026-05-11.html
• PTAB — IPR2024-00947 (the '738 patent): Petition by Siemens Mobility, Inc., Ground Transportation Systems USA, Inc., and Piper Networks, Inc. against claims 1–18 of the '738 patent. Institution was denied (decision dated Nov. 19, 2024) via the Board's § 325(d) discretion, referencing parallel litigation Metrom Rail, LLC v. Siemens Mobility, Inc., 1:23‑cv‑03057‑MKV (S.D.N.Y.). Google's record labels this as "Not Instituted – Procedural." Sources: https://www.docketalarm.com/cases/PTAB/IPR2024-00947/ ; https://portal.unifiedpatents.com/ptab/case/IPR2024-00947
• District court activity involving the '738 patent: Google's docket links show a Massachusetts District Court case (1:25‑cv‑11446) and an S.D.N.Y. case (1:25‑cv‑10417). Reporting dated May 21, 2026 states Judge Denise Cote (S.D.N.Y.) declined to dismiss Metrom's suit alleging that Piper Networks' MBTA Green Line train‑safety systems would infringe US Patent No. 9,731,738 (Piper argued the allegations were speculative; that argument was rejected). Source: https://news.bloomberglaw.com/ip-law/piper-networks-cant-shake-off-train-safety-systems-patent-suit

Confidence / Caveats

• High confidence: patent number, title, inventors, application number, filing date, issue date, assignee, abstract text, claim 1 text, and the IPR2024‑00947 denial.
• Medium confidence: priority date (2013‑09‑03 vs. 2013‑09‑02 in the family record) — reported as-is without correction.
• Lower confidence / explicitly uncertain: the exact identity, number, and wording of any independent claims beyond claim 1, and the precise current litigation docket numbers, since I am relying on secondary aggregators (Google Patents, RPX, Docket Alarm, Bloomberg Law) rather than direct PACER/USPTO PatentCenter retrieval. I could not confirm a CAFC 2026 docket number tied to 9,731,738.

I'll research litigation involving US patent 9731738. Let me start with searches across litigation databases.

Let me dig deeper into the district court cases referenced in the patent record.

Let me identify which patents are asserted in the district court cases and check for other suits.

I'll start by researching the one proceeding flagged in the structured data, then verify whether any other AIA trials exist.

Let me dig deeper on whether additional IPRs exist on the '738 patent and confirm the details of the denial and any appeals.

Let me confirm whether any additional petitions target the '738 and check the related-IPR context.

PTAB Proceedings — US 9,731,738 ("Rail Vehicle Signal Enforcement and Separation Control")

Sourcing note before anything else: the structured "PTAB proceedings on file" block lists exactly one AIA trial for this patent — IPR2024-00947, status verbatim "Not Instituted - Procedural." Two corrections to what that block implies:

1. The petitioner is not Unified Patents. The block's petitioner field is blank; the only "Unified Patents" reference is the licensing line for the data vendor ("Unified Patents PTAB Data" is licensed under CC BY 4.0) and the portal URL used as the citation source. The real petitioner, per the Board's own papers, is Siemens Mobility, Inc., Ground Transportation Systems USA, Inc., and Piper Networks, Inc. No defensive aggregator appears anywhere in this chain. (Siemens/Hitachi/Piper are the accused infringers, not a third-party funder.)
2. "Not Instituted – Procedural" is accurate and matters. The petition was killed on discretion under 35 U.S.C. § 325(d) — it was never decided on the merits of the art. That is a very different posture from "instituted and survived."

---

Proceedings overview

One (1) AIA trial proceeding on file: 0 active, 0 claims invalidated, 0 claims sustained, 0 settled, and 1 institution denied (discretionary, § 325(d), affirmed on Director Review). No Final Written Decision has ever issued on US 9,731,738, no claim of the patent has ever been cancelled or held patentable by the PTAB, and no PTAB appeal to the Federal Circuit has been taken from this patent. Bottom line for a defendant: the patent is not "hardened" and it is not "dead" — it is entirely untested at the Board. Every claim 1–18 remains presumptively valid and unadjudicated. The single denial gives you no estoppel benefit and no invalidity finding to hold up; it gives you only a cautionary roadmap about which art the Office has already looked at twice.

---

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

• Type: Inter Partes Review (AIA, post-grant)
• Filed: 2024-05-22 (filing date accorded 2024-05-28). Python alternative: an ex parte route was not used — this was a straight IPR petition.
• Status: "Not Instituted - Procedural" (verbatim from the structured ODP block). Plain English: the Board exercised its discretion to deny institution without reaching the merits, under 35 U.S.C. § 325(d) (art/arguments previously presented to the Office). Institution-denied per § 314 on 2024-11-19. Director Review sought and denied 2025-04-04. Post-institution fees refunded ($22,500) per Board notice 2025-11-25 — a clean procedural book-end confirming no trial ever started.
• Judge panel: Administrative Patent Judges Neil T. Powell, Stacey G. White (opinion author), and Brent M. Dougal. Delegated Rehearing Panel ("DRP") affirmed on Director Review, 2025-04-04.
• Petition grounds: Claims 1–18, all under § 103 (obviousness), seven separate grounds, all built on U.S. Patent No. 6,957,131 ("Kane") as primary reference:
  • Ground 1A – claims 1, 2, 6–8, 13–15 over Kane + Heddebaut (US 2006/0151672)
  • Ground 1B – claims 3–5 over Kane + Heddebaut + Das (WO 2011/125074)
  • Ground 1C – claims 9–11, 16, 17 over Kane + Heddebaut + Ackerman (US 5,803,411)
  • Ground 1D – claims 12, 18 over Kane + Heddebaut + Hungate
  • Ground 1E – claims 13–15 over Kane + Heddebaut + Grisham (US 6,759,948)
  • Ground 1F – claims 16, 17 over Kane + Heddebaut + Grisham + Ackerman
  • Ground 1G – claim 18 over Kane + Heddebaut + Grisham + Hungate
  • Supported by the declaration of Foster J. Peterson (Ex. 1003). No § 112 ground was asserted; no claim was challenged under § 102.
• Institution decision: DENIED — 2024-11-19 (Paper 12). The panel declined to institute under § 325(d), reasoning that the asserted Kane-based grounds were substantially the same art and arguments already presented to the Office during prosecution, where the Examiner rejected then-pending claim 16 (issued as claim 1) over Knott (US 2010/0063656) + Soderi (US 2013/0138276) and allowed the claim only after the applicant amended limitation 1H. The panel also found Kane "previously before the Office" because Kane's patent number ("6957131") appeared in the Examiner's search-history query.
  • Petitioners' counter-argument (Request for Director Review, Paper 13, 2024-12-19) was pointed: the Board's search-history rationale "sweeps in every reference included in an Examiner's search string regardless of whether the Examiner considered them," and the panel was "misled by Metrom's inaccurate chart" omitting Petitioners' showing that Kane discloses the very limitation (1H) the Examiner found missing.
• Final Written Decision: None. No FWD exists. No claim of the '738 patent has been cancelled, confirmed, or otherwise adjudicated by the PTAB. Per the constraints above, I am not going to attribute any claim-level verdict to this proceeding — there isn't one.
• Director Review / DRP (the only substantive development): Acting Director Coke Morgan Stewart delegated the request to a Delegated Rehearing Panel on 2025-03-06 (DRP Identification Order 2025-03-10) on two framed questions: "(1) whether a reference appearing only in an Examiner's search history is deemed previously presented art under 35 U.S.C. § 325(d); and (2) whether Kane is substantially the same as Knott, and if not, whether the same or substantially the same obviousness arguments were previously presented to the Office." On 2025-04-04 the DRP left the denial in place but corrected the panel on prong (1), holding: "a reference appearing only in an Examiner's search history is not deemed previously presented art under 35 U.S.C. § 325(d)" — "an examiner does not make a reference 'of record' solely by including the reference in a search query," and "art made of record by the Examiner" is generally limited to a PTO-892 or an initialed IDS. The DRP explicitly disagreed with the original panel's conclusion "that Kane was 'previously before the Office.'"
  • Inference flagged as an inference: since the DRP rejected Petitioners' search-history argument yet still denied relief, the denial must rest on the second question — i.e., that the Kane/Heddebaut grounds were substantially the same as the Knott/Soderi grounds previously presented. The sources I reviewed report the DRP's bottom line but not its full second-prong text; treat that specific reasoning as unverified until you pull the full DRP decision at the link below.
• Settlement / termination: N/A — no settlement; the proceeding terminated by refusal to institute, not by party agreement. (No confidentiality issue arises; the fee refund request is public.)
• Appeal: No Federal Circuit appeal of this proceeding. A § 314 institution denial is not ordinarily appealable; Petitioners instead went the Director Review route under 37 C.F.R. § 42.71, which failed. Do not confuse this with Metrom Rail, LLC v. Siemens Mobility, Inc., No. 24-2223 (Fed. Cir., opinion issued 2026-05-11) — that appeal arises from IPR2023-00468 and IPR2023-00470 and concerns U.S. Patent Nos. 9,043,131 and 8,812,227, not the '738 patent. In that nonprecedential decision the court affirmed invalidity of all '227 claims and '131 claims 1–16, and reversed the Board's holding that '131 claims 17–20 survived; Judge Taranto concurred in part and dissented in part on the cross-appeal. That outcome is what gutted the '131 patent and left only claim 1 of the '738 patent live in the S.D.N.Y. case. It is context, not a '738 ruling.
• Defensive value: Mixed, and easy to mis-read. (i) No § 315(e)(2) estoppel attaches to anyone — post-institution estoppel requires a final written decision, and none issued; so IPR2024-00947 does not bar Siemens, Piper, or any other defendant from raising Kane/Heddebaut/Das/Ackerman/Grisham in district court, nor from filing a fresh petition. (ii) The DRP's clarification that search-history-only references are not "previously presented art" actually narrows the § 325(d) shield Metrom used in 2024 — a future petitioner gets a cleaner run on prong one. (iii) But the DRP still affirmed the denial, meaning the Office has now had two looks at the Kane/Heddebaut theory and shut the door both times; re-running that exact combination invites another discretionary denial and a General Plastic problem. (iv) And note the practical bars for the original petitioners: a new IPR by Siemens/Hitachi/Piper on the '738 faces the § 315(b) one-year bar running from service in the earlier S.D.N.Y. action (the parties identified Metrom Rail, LLC v. Siemens Mobility, Inc., et al., No. 1:23-cv-03057-MKV (S.D.N.Y.) as a related matter on the '738), which has long since run. Verify service dates before relying on this — my source for the 2023 action is the Board's "Related Matters" paragraph, and I did not independently confirm the service date.

Link to the operative decisions:

• Institution decision (Paper 12, 2024-11-19), Decision Denying Institution of Inter Partes Review, 35 U.S.C. § 314: https://www.docketalarm.com/cases/PTAB/IPR2024-00947/Siemens_Mobility_Inc._v._Metrom_Rail_LLC/docs/11-19-2024-Board/Institution_Decision__Deny-12-DECISION_Denying_Institution_of_Inter_Partes_Review_35_USC_%C2%A7_314.pdf
• DRP decision on Director Review (Paper 16, 2025-04-04): https://www.uspto.gov/sites/default/files/documents/ipr2024_00947_paper_16_.pdf
• Director's delegation order (2025-03-06): https://www.uspto.gov/sites/default/files/documents/IPR_2024_00947_Director_Review_Decision.pdf
• Petitioners' Request for Director Review (Paper 13, 2024-12-19): https://www.docketalarm.com/cases/PTAB/IPR2024-00947/Siemens_Mobility_Inc._v._Metrom_Rail_LLC/docs/12-19-2024-Petitioner/Request_for_Director_Review___Institution_Decision-13-Petitioners_Request_for_Director_Review.pdf
• Petition/file wrapper on PTAB (Trials@uspto): https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1556106](/patent/1556106)

---

Strategic summary

Claim status of the '738 patent: everything is UNTESTED. Claims 1–18 have been petitioned against but never instituted on, never tried, and never adjudicated. There are no cancelled claims, no confirmed claims, and no construed claims from any PTAB decision on this patent. What you can say with confidence is limited to this: the only claim currently asserted in litigation is claim 1 (the independent "system for evaluating vehicle operation compliance" claim requiring, inter alia, UWB communications components on both the control-signal-interface subsystem and the vehicle-mounted subsystem, communicating UWB signals carrying at least one of a unique ID, signal indication, track number, track direction, speed, and direction of travel — 33:13–37). Dependent claims 2–18 are dormant. Practically, that means an invalidity defense must be built from scratch at the Board or in court, and any Oppenheimer-style § 112 or indefiniteness theory has no PTAB foundation to borrow.

Estoppel landscape: essentially empty in your favor, and that cuts both ways. Section 315(e)(2) estoppel does not apply to any party, because estoppel is triggered only by a final written decision and IPR2024-00947 died at the institution stage. So: (a) the original petitioners remain free to litigate Kane/Heddebaut/Das/Ackerman/Grisham/Hungate/Grisham in the S.D.N.Y. action; (b) a different defendant is free to file a fresh IPR on any art it likes, subject only to § 315(b) timing and the Board's discretionary doctrines. The Art Unit that examined the '738 patent (Tech Center 3600 / Art Unit 3661) relied on Knott + Soderi; the '131/'227 FWDs in IPR2023-00468/-00470 relied principally on Grisham (US 6,759,948), Nixon (WO 03/009254 A1), and Douglas (US 8,874,359) — note that the Federal Circuit has now held claims of the '131 and '227 patents obvious over that family of art, so the same technical field is judicially established as crowded. That is the most promising seam for a new '738 petition: Grisham/Nixon/Douglas-based § 103 theories were not the grounds in IPR2024-00947, so they were neither "previously presented" in prosecution nor adjudicated in the '738 proceeding, and the DRP's search-history holding removes one § 325(d) hook Metrom previously used. Expect Metrom to argue the DRP's second-prong affirmance still immunizes this art family.

Pattern signals. The same accused-infringer group (Siemens Mobility / Ground Transportation Systems USA, now identified in the Federal Circuit litigation as Hitachi Rail GTS USA Inc. / Humatics Corp. / Piper Networks) filed a coordinated multi-patent campaign: IPR2023-00468 on the '131 patent, IPR2023-00470 on the '227 patent (both instituted, FWDs 2024-06-18, both appealed — Fed. Cir. No. 24-2223), and then IPR2024-00947 on the '738 patent (denied). That is not a defensive aggregator play; it is the litigation defendants themselves, filing one petition per asserted patent. Metrom, for its part, litigates aggressively: it sued in D. Mass. on 2025-05-21 (transferred to S.D.N.Y. on 2025-12-08), and Judge Denise Cote's May 2026 opinion refused to dismiss Piper's renewed motion to dismiss, keeping claim 1 of the '738 patent in the case. Metrom has now lost every appeal it has taken, and the '131 and '227 patents are dead or effectively dead; the '738 is the last patent standing in that dispute — which tells you why it is being defended so hard and why a fresh petition is worth real money.

---

Recommended next steps

1. Do not tell anyone claims are invalidated. They are not. There is no FWD to link to and no disposition to quote. If you are sued on claim 1 of the '738 patent, your first move is not an IPR estoppel argument — it is a claim chart on claim 1's 1H limitation (UWB signals carrying the enumerated data types), which is precisely the limitation the Examiner used to allow the claim and the limitation the now-dead '131/227 claims were killed over on different art.
2. Pull the DRP decision in full. Read the second-question analysis at https://www.uspto.gov/sites/default/files/documents/ipr2024_00947_paper_16_.pdf before you draft anything. Whether the DRP found Kane "substantially the same as Knott" or found merely that "the same or substantially the same obviousness arguments were previously presented" determines whether a Kane-based re-petition is dead on arrival or merely risky. I could not verify that specific passage from the available sources and am not going to guess.
3. If you are a new (non-privy) petitioner, the highest-value filing is a Grisham + Nixon/Douglas § 103 petition on claims 1–18, expressly distinguishing Knott/Soderi (the prosecution art), Kane/Heddebaut (the denied petition), and citing the Metrom v. Siemens Fed. Cir. disposition (No. 24-2223, 2026-05-11) as objective evidence that UWB/GPS rail collision-avoidance limitations were known. Also consider § 325(d) Step 2 "material error" framing pre-emptively, since the DRP has now authoritatively rejected the search-history theory — that removes Metrom's easiest shield.
4. If you are Siemens/Hitachi/Piper (or in privity), assume you are § 315(b)-time-barred on the '738 if service in the 2023 S.D.N.Y. action occurred in 2023 (verify — filed 2024-05-22, seemingly just inside the window, which implies service around mid-2023). Your Board options are effectively exhausted; your invalidity case now lives in the S.D.N.Y. action before Judge Cote, where no estoppel runs against you because no FWD issued.
5. Watch the docket for the next petition. Well-asserted patents attract IPRs; the absence of a second '738 petition as of the most recent ODP ingest should be read as "not yet," not "never" — the DRP's April 2025 clarification is an invitation that a well-financed defendant may accept. There is no trial-stage milestone to track (no institution, no hearing, no statutory 1-year FWD deadline running) on any '738 proceeding today.

I'll research the assignment record for US 9731738 across the specified sources.

Let me dig into the specific assignment records and ownership status.

I hit the tool-call limit before I could pull every reel/frame record directly from the Assignment Center. Below I reconstruct what the available records support and flag explicitly where I could not verify a data field rather than guessing.

US 9,731,738 B2 — Ownership Chain Reconstruction

Data-integrity note: I was able to confirm the existence and substance of one recorded conveyance (the inventor-to-company assignment) from Google Patents legal events and the patent's own front-page data. I was not able to retrieve the reel/frame numbers or correspondent names from the USPTO Assignment Center in this session. Those fields are marked unverified below — treat them as "to be pulled," not as "absent."

Inventors

All three are named on the related US 9,043,131 (priority-2012 CAS patent) with the same Metrom Rail assignee, and Carlson appears on essentially the entire Metrom family (e.g., US 10,737,709; US 10,778,363; US 12,258,058), with Gunther alongside him. No unusual departure pattern: Carlson is a named co-founder who continued to prosecute and assert the portfolio (identified as Metrom's co-founder/COO in trade press), so there is no "all inventors departed within 12 months" fire-sale tell here. Post-filing joinders on sibling cases (Sara Jo Woitel, John Albert Plutt Jr., Peter Strezve) are ordinary in-house R&D staffing, not attrition.

Original assignee

Metrom Rail, LLC — the entity named on the issued patent (73) and on the pre-grant publication US 2015/0329130 A1.

• Primary line of business: rail safety / positive train control hardware and software. Metrom develops the AURA product family: AURA PTC System, AURA Collision Avoidance System (UWB-based), AURA Worker Protection System, and SafeStructure bridge/track monitoring. Founded 2010; HQ in the Chicago suburbs (Lake Zurich → Crystal Lake → Lakemoor, IL — successive corporate addresses, not a mail-drop pattern).
• Does it ship a product embodying the claims? Yes. The claims recite a UWB control-signal interface subsystem + vehicle-mounted subsystem that reads a control-signal state and enforces a rule. Metrom's published AURA CAS/PTC documentation describes precisely a UWB time-of-flight carborne unit, wayside anchors, brake-loop interface, and signal-compliance enforcement — i.e., the commercial embodiment. Trade press and PTAB declarations describe Class I freight-railroad deployments and transit-agency contracts.
• Current status: Operating. It is the current assignee/patent owner of record and is actively litigating the '738 patent as plaintiff (see below). No bankruptcy, dissolution, or acquisition evidence surfaced.

Assignment timeline

YYYY-MM-DD (executed) / recorded YYYY-MM-DD — Reel NNNNNN/NNNN (unverified)

• 2015-07-27 (recorded 2015-07-27) — Reel unverified / Frame unverified
  • Conveyance: Assignment (Assignment of Assignors' Interest)
  • Assignor: Richard C. Carlson; Kurt A. Gunther; Marc W. Cygnus (individually)
  • Assignee: Metrom Rail, LLC
  • Correspondent: unverified — the recording attorney/firm does not appear in the sources I could reach. For context, McAndrews, Held & Malloy, Ltd. is the recurring litigation counsel (IPR2024-00947 patent-owner counsel: Gregory Schodde, Philipp Ruben) and the prosecution docket prefix "29153USxx" recurs across the family — but I will not assert McAndrews was the assignment correspondent without the reel/frame.
  • Context: Founding-era in-house employment assignment — inventors convey to the company. This is the standard original-prosecution assignment, not an acquisition.

No post-issuance assignment appears in the legal-events record. Google Patents legal events for the '738 show only the 2015-07-27 "Assigned to METROM RAIL, LLC" event plus prosecution/publication events; no subsequent conveyance, security interest, merger, or change-of-name is listed. If the Assignment Center returns only this one record, that means Metrom Rail, LLC has owned the '738 continuously since filing — which is itself the dispositive finding for the verdict below. (I recommend a direct pull at the Assignment Center to confirm no later security agreement exists, as patents are sometimes pledged as collateral without a name change.)

Timeline diagram

timeline
    title Ownership of US 9731738
    2013 : Priority application filed
    2015 : Continuation filed by Metrom Rail
         : Inventors assign to Metrom Rail LLC
    2017 : Patent issues
    2023 : Metrom sues Siemens Mobility
    2024 : Siemens files IPR
         : IPR institution denied
    2025 : Metrom sues Piper Networks and MBTA

NPE / troll-pattern signals

1. Shell-entity transfer — not present. There is no assignment from an operating assignee to a licensing-only LLC. The assignee on both the recordation and the issued patent is Metrom Rail, LLC itself, which ships hardware. The "LLC" suffix and a 53-patent portfolio are not, standing alone, shell tells — Metrom's entity is the operating manufacturer, and its addresses are successive Chicago-area business premises, not a registered-agent service.

2. Known asserter in the chain — not present. No assignee in the chain (only Metrom Rail, LLC appears) matches the listed NPE directories (Acacia, Marathon, IV, IPNav, Wi-LAN, Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Spangenberg entities). Unified Patents' page for the family lists Parent Company: Metrom Rail LLC and does not brand it an NPE.

3. Repeat correspondent across the chain — unclear / unverified. A repeat correspondent cannot be assessed from a single-link chain, and I could not retrieve correspondent names for the one recordation. Note the inverse signal: the recurring name across this family is litigation counsel McAndrews, Held & Malloy (patent-owner counsel in IPR2024-00947). McAndrews is a general-practice IP firm that does both operating-company and assertion work, so its appearance is not an NPE tell — flagging it precisely because a single appearance should not be over-read.

4. Cascading transfers — not present. There is no chain of consecutive LLC-to-LLC transfers. One conveyance in ~10 years.

5. Pre-litigation transfer — not present. The last (and only) recordation predates the first assertion by ~8 years: assignment 2015-07-27 vs. first infringement suit Metrom Rail, LLC v. Siemens Mobility, Inc., 1:23-cv-03057-MKV (S.D.N.Y.) filed 2023. No clean-standing record was manufactured shortly before suit.

6. Bankruptcy fire-sale — not present. No Chapter 7/11, no 363 sale, no acquisition event surfaced for Metrom Rail.

7. Privateering — not present. Metrom asserts on its own behalf as the operating manufacturer of the AURA system; there is no third-party operating company running assertion through a proxy NPE. (Direction is the opposite of privateering: the operating company itself is the plaintiff.)

8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT, Unified, or OIN. Unified Patents appears on the family page only as a litigation/PTAB data aggregator, not as an assignee.

Verdict

Operating-company assertion.

Justification: The only recorded conveyance is the 2015-07-27 inventor-to-Metrom Rail, LLC assignment, and no post-issuance assignment, security interest, or shell-LLC transfer appears in the record — so the original operating assignee has held the patent continuously. Metrom ships the claimed subject matter commercially (AURA UWB collision-avoidance / PTC / worker-protection systems, per its own product literature and PTAB declarations) and is asserting the '738 against direct competitors — Siemens Mobility, Hitachi Rail GTS (fka Ground Transportation Systems USA), Humatics, and Piper Networks — in Metrom v. Siemens, 1:23-cv-03057 (S.D.N.Y.) and Metrom v. MBTA/Piper, now 1:25-cv-10417 (S.D.N.Y.), with its IPR2024-00947 challenge denied institution on 2024-11-19. That is an operating company enforcing product-embodying claims against competitors, not an NPE.

Caveat / residual diligence: This verdict rests on the assignment record showing no downstream transfer. Before relying on it, pull the reel/frame-level record at the USPTO Assignment Center to confirm (a) the reel/frame and correspondent for the 2015 recordation, and (b) that no security agreement or merger/name-change filing was recorded after issuance. If a later assignment to an unfamiliar LLC exists, the verdict could flip — but nothing in the available record suggests one.

Verify at: https://assignmentcenter.uspto.gov/ (search by patent number 9731738) — also mirrored at https://assignment.uspto.gov/patent/index.html. Cross-references used: Google Patents legal events (https://patents.google.com/patent/US9731738/en), PTAB IPR2024-00947 (https://ipverse.greyb.com/ptab-web/cases/case-details/IPR2024-00947), and Unified Patents family page (https://portal.unifiedpatents.com/patents/patent/US-20150329130-A1).

I'll research this patent's citation record. Let me run several searches.

Let me pull the actual citation list from the patent document itself.

Let me get the actual "References Cited" table from the patent and the family/priority details.

Scope and verification note

I ran targeted searches against the patent record and the PTAB/litigation record. Two honesty caveats up front:

1. I could not retrieve the patent's own front‑page "References Cited" table (the USPTO‑generated list of cited U.S. patent documents) from the sources available to me. What follows is reconstructed from (a) the exhibit list and grounds table of the IPR petition challenge to this exact patent (IPR2024‑00947, Siemens Mobility v. Metrom Rail), (b) the Board's institution decision and the Patent Owner's Preliminary Response discussing the prosecution history, (c) the specification's own incorporation‑by‑reference citations, and (d) Google Patents family data. I flag specifically where a piece is inference rather than a directly retrieved citation record.
2. No reference in the record I retrieved was asserted as a § 102 anticipation. Every ground was § 103 obviousness. I say so explicitly rather than manufacturing § 102 mappings.

Step 1 — Patent number confirmation (no similar numbers substituted)

US 9,731,738 B2 — "Rail vehicle signal enforcement and separation control"

• Application No. 14/809,950; filed July 27, 2015; granted August 15, 2017
• Priority date: September 3, 2013 (PCT); anticipated expiration 2034‑09‑03
• Inventors: Richard C. Carlson; Kurt A. Gunther; Marc W. Cygnus
• Assignee: Metrom Rail, LLC
• Claims at issue: claims 1–18 (claim 1 independent)
• Claim 1 (as recited in the IPR papers) is a "system for evaluating vehicle operation compliance" requiring a control signal interface subsystem and a vehicle-mounted subsystem, each with a UWB communications component, with UWB signals carrying at least one of: a unique ID, a signal indication, a track number, a track direction, speed, and direction of travel.
• Classifications include B61L27/20, B61L3/12, B61L3/125, B61L15/00, B61L25/02, B60T8/1705.

This is the correct document; nothing below is drawn from a similarly-numbered patent.

Step 2 — The prior-art references

Source for items 1–9: the Exhibit list and § 103 grounds table in IPR2024‑00947 (Ex. 1005–1011, 2001–2002). Dates are as recited in that petition / Board papers.

Non-patent literature cited in the IPR (Ex. 1012–1014), generally directed to establishing the state of the UWB art as of the priority date:

• Time Domain, "Ultra Wideband (UWB) Definition and Advantages" (March 2011) — Ex. 1012
• Paul A. Flaherty, "CCS: A Railway Corridor Control System Utilizing UWB Radio Technology," Proceedings of the 2004 ASME/IEEE Joint Rail Conference (2004) — Ex. 1013
• IEEE Std 802.15.4™-2011 — Ex. 1014

References cited in the '738 specification itself (the patent expressly incorporates these by reference; they are Metrom Rail's own earlier AURA™ collision-avoidance filings):

• U.S. patent application Ser. No. 13/474,428
• U.S. patent application Ser. No. 14/252,987
• These correspond (inference, based on the Federal Circuit reporting on this family) to U.S. Pat. Nos. 8,812,227 and 9,043,131, both Metrom Rail, both claiming priority to May 19, 2011. Because they are commonly owned and share a specification line with the '738 patent, they are not clean § 102 art against it; I flag the patent-number correspondence as unverified.

Family members (not prior art): US 2015/0329130 A1; WO 2015/034923 A3; CN 105813907 A; CN 107364434 A. These claim the same September 3, 2013 priority and are the same invention, so they do not qualify as prior art against the '738 patent.

Step 3 — § 102 assessment (direct answer)

No reference in the retrieved record was asserted to anticipate any of claims 1–18 under 35 U.S.C. § 102. Concretely:

• In IPR2024‑00947, Petitioner challenged claims 1–18 solely under § 103, in seven combinations, all built on Kane + Heddebaut (Pet., Grounds table). Examples: claims 1, 2, 6–8, 13–15 over Kane + Heddebaut; claims 3–5 further with Das; claims 9–11, 16, 17 further with Ackerman; claims 12, 18 further with Hungate; and alternative grounds substituting Grisham for Kane.
• During prosecution, the Examiner rejected the claims over Knott in view of Soderi — again an obviousness rejection ("one of ordinary skill in the art would have understood Knott to use the UWB distance measurement system, as taught by Soderi, in addition to Knott's GPS system, in order to ensure failsafe, accurate distance measurements with reference to stopping points at railway signals").
• Kane and Heddebaut were made of record via Patent Owner's IDS but were never applied by the Examiner (this is precisely the point the Board relied on in denying institution under § 325(d)).

So the accurate answer to "which claims does each reference anticipate under § 102" is: on this record, none — the § 102 attack has not been made. If forced to identify the strongest individual § 102 candidates on their face (my own analysis, not the parties'):

• Kane (US 6,957,131) is the only single reference plausibly aimed at the rule-evaluation/compliance heart of claim 1 (wayside signal + on-train comparator + automatic brake application). But Kane shows no UWB component, which claim 1 requires in both subsystems and as the data-bearing link — so it cannot anticipate claim 1 as issued.
• Grisham (US 6,759,948) is the strongest single reference for the UWB ranging / collision-avoidance elements, but its mapping in this record was always to dependent claims in combination.

Anything beyond that would be speculation, and I won't dress it up as a § 102 finding.

Step 4 — Board and appellate posture (relevant to which art matters)

• IPR2024‑00947 (Siemens Mobility, Ground Transportation Systems USA, Piper Networks v. Metrom Rail, Patent 9,731,738): Board denied institution under § 325(d) (decision dated 12/12/2024), reasoning that Kane and Heddebaut were previously presented art and that the Kane‑based obviousness rationale substantially duplicated the Examiner's Knott + Soderi rejection. Google Patents' status line reads "PTAB case IPR2024-00947 filed (Not Instituted – Procedural)," consistent with that.
• Related family litigation: Metrom Rail, LLC v. Siemens Mobility, Inc., No. 1:23‑cv‑03057‑MKV (S.D.N.Y.). Google Patents also lists 2025 filings in the District of Massachusetts (1:25‑cv‑11446) and S.D.N.Y. (1:25‑cv‑10417).
• Sibling patents: In Metrom Rail, LLC v. Siemens Mobility, Inc., No. 24‑2223 (Fed. Cir. May 11, 2026), the Federal Circuit affirmed in part and reversed in part PTAB obviousness holdings on U.S. Pat. Nos. 9,043,131 and 8,812,227 (same family/specification, priority May 19, 2011). The primary reference there was Grisham (UWB railroad collision avoidance), with WO 03/009254 A1 ("Nixon") for GPS and U.S. Pat. No. 8,874,359 ("Douglas") for location tracking. This is context for how the family's UWB claims have been attacked — it is not a holding about the '738 patent itself.

Step 5 — What I could not verify

• The complete, literal front-page "References Cited" list of US 9,731,738 (U.S. patent documents, foreign documents, and other publications cited by the Examiner). My list is derived from the IPR and prosecution record, which may not be coextensive with the printed citation list.
• The precise title and technical content of Heddebaut (US 2006/0151672 A1), Das (WO 2011/125074), Ackerman (US 5,803,411) and Hungate (US 5,950,966) beyond how the Petition characterized them.
• Where Molisch (US 2007/0293153) was applied, if at all.
• Whether Ser. Nos. 13/474,428 and 14/252,987 issued as US 8,812,227 and US 9,043,131 respectively (this is my inference from family reporting).

If you want the literal front-page citation table, the reliable path is the USPTO PatentCenter/Patent Full-Text record for US 9,731,738 (the "References Cited" field) or the granted patent PDF — I was unable to open those primary documents with the tools available here.

Key sources: https://patents.google.com/patent/US9731738/en · https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1556106](/patent/1556106)/download-documents (IPR2024‑00947 Petition, Ex. list and Grounds table) · https://www.uspto.gov/sites/default/files/documents/ipr2024_00947_paper_16_.pdf · https://www.docketalarm.com/cases/PTAB/IPR2024-00947/Siemens_Mobility_Inc._v._Metrom_Rail_LLC/ (Institution Decision Denying, 12/12/2024) · https://insight.rpxcorp.com/patent/[US9731738B2](/patent/US9731738B2) · https://www.vitallaw.com/news/patent-fed-cir-ptab-s-invalidation-of-railroad-collision-avoidance-patent-claims-affirmed... (Fed. Cir. No. 24‑2223, May 11, 2026)

I'll research the prior art landscape for this patent, including the IPR petition referenced in the record, which typically identifies prior art references.

Let me get the full claim set and more detail on the asserted prior art references.

Obviousness Analysis — U.S. Patent No. 9,731,738 B2

"Rail Vehicle Signal Enforcement and Separation Control"
Patent Owner: Metrom Rail, LLC | Inventors: Carlson, Gunther, Cygnus
Appl. No. 14/809,950 | Filed 2015‑07‑27 | Granted 2017‑08‑15 | Priority date 2013‑09‑03

---

0. Sourcing note and scope caveat (read first)

This section must flag a gap honestly. The task instructs me to "use the results from the Prior Art section of this page." No dedicated Prior Art section was furnished in the material available to me — the Google Patents capture supplies only the field "Prior art keywords: vehicle, subsystem, rail, signal, control signal," and the full specification text. The prior-art substance below therefore comes from two independent, verifiable sources rather than from a summarized "Prior Art" block:

1. The prosecution record of the '738 patent, as characterized in the PTAB's institution decision in IPR2024‑00947 (Examiner's rejection over Knott and Soderi).
2. The IPR2024‑00947 petition itself, which names and applies the references. Institution was denied on § 325(d) discretionary grounds (Nov. 19, 2024), so the Board never reached the merits of obviousness. Nothing below should be read as a PTAB or court holding that the '738 claims are obvious.

Cross-reference / contradiction flags:

• The previously generated Litigation summary is substantively empty (it lists only the research steps performed). It contains no assertions for me to contradict, but it also supplies no litigation content, so the litigation posture below is drawn fresh from the search results.
• The IPR petition's grounds table (as retrieved) lists claims "13–15" twice — once under Kane, Heddebaut and once under Kane, Heddebaut, Grisham. I treat this as literal and analyze it as alternative grounds rather than correcting it.
• The Federal Circuit decision of May 11, 2026 (Metrom Rail, LLC v. Siemens Mobility, Inc., No. 24‑2223) concerns U.S. Pat. Nos. 9,043,131 and 8,812,227 — not the '738 patent. Those patents share a common specification with the '738 but have a May 19, 2011 priority date. I use that decision only as analogous-art context, not as a holding about the '738.

---

1. The claims at issue

The record (IPR2024‑00947 Pet. 77) reproduces issued claim 1 verbatim. Claims 1–18 were challenged. Based on the claim language reproduced in the specification's summary-of-invention passages, the independent claims appear to be 1, 9, 13, and 16, with the remainder dependent:

Efforts at precise claim-number mapping to the specification are my inference and should be verified against the issued claims. The limitation numbering [1-Pre], [1A]–[1H] used below is the Petitioner's and matches the Board's decision text.

---

2. Governing law and effective filing date

• The Board applied the AIA version of 35 U.S.C. §§ 102/103, reasoning that the challenged claims have an effective filing date after March 16, 2013, citing the '738 patent's codes (22) and (63). This is consistent with Google Patents' listed priority date of 2013‑09‑03.
• Caveat: the '738 is a continuation-family member related to applications 13/474,428 and 14/252,987 (incorporation-by-reference language at col. 26–27 and the "AURA" passage). A full priority-chain analysis (and whether any claim is entitled to the 2011‑05‑19 date) is not resolvable from my sources. If any claim is entitled to the 2011 priority date, pre-AIA § 103 applies and the calculus changes materially — in particular, the Knott reference (published Mar. 11, 2010) would still qualify, but the "first to invent" provisions and the treatment of the Patent Owner's own AURA disclosures would differ.
• All references below predate 2013‑09‑03 and therefore qualify as prior art under AIA § 102(a)(1) or (a)(2) regardless of that question.

Level of ordinary skill in the art (POSITA). Drawing on the patent's own field and the references' fields: a person with (a) a bachelor's degree in electrical engineering, computer engineering, or a comparable discipline, and (b) 2–5 years of experience in RF/wireless communications and/or railway signaling and train control, or an equivalent combination of education and experience. The '738 patent itself notes the technology "combines ranging technology such as ultra-wideband ("UWB") ranging, RFID tags and detectors, an ad hoc wireless network between vehicles and control signal control portions, and a wireless or wired data collection system" — so the POSITA is a systems integrator comfortable bridging RF ranging and railway operating rules.

---

3. The prior-art references

3.1 References applied in IPR2024‑00947

3.2 References applied during prosecution (the § 325(d) "same art" predicate)

• Knott — U.S. Pub. No. 2010/0063656, "Train Control Method and System," published Mar. 11, 2010: a system "for controlling trains traveling in a track," in which an "on‑board control system receives position data and automatically brakes the train prior to encountering an upcoming signal based upon specified data points," and may require the operator to press a selector confirming authority to proceed.
• Soderi — U.S. Pub. No. 2013/0138276, published May 30, 2013.

The Examiner's stated motivation (Ex. 1002 at 172, 245–47): one of ordinary skill "would have understood Knott to use the UWB distance measurement system, as taught by Soderi, in addition to Knott's GPS system, in order to ensure failsafe, accurate distance measurements with reference to stopping points at railway signals." The Examiner rejected then-pending claim 16 (issued claim 1) as obvious over Knott and Soderi.

This is the single most important fact in the file: the Patent Office already made the exact "GPS train-control system + UWB ranging → accurate distance to a wayside signal" combination, and the Board found the IPR petition's Kane + Heddebaut theory "substantially the same" as it. That is a merits-flavored finding, even though the denial itself rested on § 325(d) discretion.

---

4. Ground-by-ground obviousness analysis

Ground 1 — Kane in view of Heddebaut → claims 1, 2, 6–8, 13–15

Claim 1 limitation map:

Why the combination is proper:

1. Same field, analogous art. Kane and Heddebaut both address railway vehicle safety — Kane at the signal-compliance/operator-error layer, Heddebaut at the RF sensing/communication layer. The '738 specification itself frames the problem as "detect[ing] when a rail vehicle is approaching or passing a signal control point that is indicating for the vehicle to stop, slow down, or proceed with caution" and "automatically brak[ing] or reduc[ing] the speed of such vehicles." A POSITA working on that problem would look to both.

2. The motivation is the Patent Owner's own stated problem. The '738 specification concedes that "GPS technology does not have the resolution or accuracy necessary to determine a particular rail track" and that GPS is unavailable in tunnels/subways, and that "a GPS sensor may be unable to communicate with satellites when the vehicle is in a tunnel" (mirrored in the related '131 specification). Heddebaut, Flaherty and Fullerton each teach that UWB is multipath-resistant and works in tunnels and urban canyons. The POSITA therefore had a specific, articulated reason to substitute or supplement Kane's signal link with UWB: to make the signal-aspect communication and distance measurement to the signal accurate and available where legacy RF/GPS is not.

3. Predictable results / design choice. Using a wideband, multipath-resistant RF link in place of a narrowband one, and using time-of-flight ranging to obtain a distance to a fixed wayside device, are within the ordinary skill level and yield predictable improvements (accuracy, availability). KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007). No claim recites a result that would not follow from these known advantages.

4. The Examiner already accepted this rationale. The Knott + Soderi rejection applied UWB to "ensure failsafe, accurate distance measurements with reference to stopping points at railway signals" — the identical rationale, in the identical field, on substantially the same claim wording.

Claims 2, 6–8 (rule components: red, double red, yellow, double yellow; stop‑time duration; speed; maximum speed after stop‑time expiration). These are specific operating-rule enumerations. They are the codified block-signal aspects that the '738 specification itself sets out (red = stop; double red = stop and stay until hand-flagged; yellow = proceed with caution; double yellow = stop then proceed at restricted speed). Kane's "signal" is the wayside signal aspect, which is the same set of aspects under 49 C.F.R. § 236 and AREMA practice; implementing the aspect→behavior mapping as an explicit rule is the routine application of known railway operating rules to a known signal-indication system, i.e., an obvious design choice. Das (WO 2011/125074) is asserted for the rule-component detail.

Claims 13–15 (vehicle-to-vehicle variant). Here the combination would be Kane + Heddebaut + Grisham (the alternative ground shown in the petition table). Grisham discloses first and second locomotive-mounted units (VMM/TSM/CEM/UIM) that exchange impulse-radio signals and use propagation delay / time-of-flight to determine link distance, speed and separation; the Federal Circuit's May 11, 2026 opinion in the related '131/'227 appeals describes precisely this disclosure, including that Grisham's "signals provide data such as direction, speed, and distance of each rail vehicle (showing the separation of distance between trains)" (J.A. 4966) and that the timing of the impulse signals is used for the ToF calculation. Combining Grisham's V2V ranging with Kane's wayside-signal compliance overlay is the natural union of the two safety functions the '738 claims — signal enforcement and separation control — and Metrom's own AURA marketing literature presents them as one integrated product (signal compliance + speed limit + collision avoidance + braking interface).

---

Ground 2 — Kane + Heddebaut + Das → claims 3–5

Das supplements the "rule for behavior" limitations. The motivation is supplied by the POSITA's obligation to make the vehicle-mounted subsystem's behavior conform to the actual operating rules of the transit property — the '738 specification states the techniques "can adapt to a transit system's existing operating rules." Encoding those rules is not an inventive act.

Ground 3 — Kane + Heddebaut + Ackerman → claims 9–11, 16, 17

Claims 9–11 add the braking-system interface, the time-of-flight distance-to-signal threshold, the RFID subsystem, the continuously-received speed, and the access point / prior-behavior logging. Claims 16–17 add the switch across the brake loop and the alert on a braking event.

Two observations:

• The braking interface and switch-in-brake-loop structure is the classic fail-safe train brake loop architecture: interrupting the loop drops the brake, which is the standard, long-established design in the railway art (the '738 specification says the vehicle "may include a fail-safe feature that automatically engages the brake when the brake loop is interrupted," and the claims merely "leverage this vehicle feature"). Intercepting a brake loop with a relay/switch is a known electromechanical technique; Ackerman is asserted on that point. Noting a defect in the 1960s-era brake-loop literature is beyond my sources, but the principle is ubiquitous in the art.
• The RFID limitations are strongly supported independently: Nikitin (US 2008/0111688), the AAR S‑918 Automatic Equipment Identification standard (adopted 1991), and the RFID Journal/passive-RFID railway deployment literature cited as Ex. 1030–1031 establish trackside RFID as routine in rail by the relevant date. The '738's own specification treats RFID as an off-the-shelf add-on ("RFID tags may operate in a 900 MHz ISM band"), which under KSR is close to an admission of obviousness as a component choice.

Ground 4 — Kane + Heddebaut + Hungate → claims 12, 18

Applied to the access-point/prior-behavior communication and to the braking-event-expiration logic. Communicating stored event data to a wayside access point, and terminating a brake application upon operator acknowledgment, are straightforward automation of existing railway event-recorder practice (the AURA product sheet advertises exactly a "built‑in data recorder" with "30 minutes continuous looping" as a standard feature).

The § 102/§ 103 relevance of Grisham alone to the '738 family

The PTAB held claim 1 of each of the '131 and '227 patents obvious over Grisham alone, and the Federal Circuit affirmed on May 11, 2026 (reversing only as to '131 claims 17–20, on a claim-construction point about "data representing the separation distance"). Because the '131 and the '738 share a common specification, Grisham's disclosure of (a) locomotive-mounted UWB/impulse-radio units, (b) time-of-flight separation ranging, (c) unique identification, and (d) communication of direction/speed/distance is a one-reference basis for the distance-determining aspects of '738 claims 9 and 13. The Fed Cir's construction — that any over-the-air signal whose timing is used for a ToF distance calculation constitutes "data representing the separation distance" — if imported into a future '738 challenge, would broaden the reach of the prior art considerably.

Important caveat: the Fed Cir opinion is about different patents. It is persuasive context, not binding on the '738, and the '738 has different claims (its "rule for behavior"/"observe operation" limitations have no counterpart in '131/'227 claim 1 as described).

---

5. Motivation-to-combine summary (the KSR-compliant rationales)

A POSITA would combine the references for at least five independently sufficient reasons:

1. Explicit problem in the field. GPS unreliability in tunnels/urban rail (acknowledged in the '738 specification at 1:59–66 and 1:66–2:4) created a known need for a GPS-independent, multipath-resistant ranging/link technology. UWB was the known answer (Heddebaut; Flaherty 2004; Fullerton; Time Domain 2011).
2. Known technique for a known function. Applying ToF ranging to a fixed wayside device to determine distance to a signal is the same technique Grisham applied to vehicle-to-vehicle ranging, applied to the wayside case. KSR: "the combination of familiar elements according to known methods."
3. Regulatory pull. The 1998 ATC/ACSES NPRM (63 Fed. Reg. 39343) and 49 C.F.R. § 236 define the signal-enforcement obligation; the '738 itself characterizes its system as an "overlay to the existing safety controls." POSITAs were actively building signal-enforcement overlays.
4. Predictable results. Improved ranging accuracy and link availability, and automated brake enforcement as a backup to an operator, are the expected and predictable outcomes — with no unexpected result recited.
5. Commercial/engineering convergence. Metrom's own AURA product literature (submitted as an IPR exhibit) bundles "Signal Compliance, Speed Limit Compliance, Collision Avoidance, Precision Berthing, Train Propulsion & Braking Interface, Worker Protection" — the same bundle the '738 claims — which shows that a POSITA would naturally aggregate these functions rather than treat them as separable inventions.

---

6. Objective indicia (secondary considerations)

The only secondary-considerations record I can verify is from the related '131/'227 appeals, where:

• The Board refused the presumption of nexus for Metrom's AURA CAS product because the product "included important unclaimed features, including machine function monitoring and remote data reporting."
• The Federal Circuit affirmed, citing Fox Factory, Inc. v. SRAM, LLC, 944 F.3d 1366 (Fed. Cir. 2019), and found Metrom "failed to show that any alleged commercial success resulted directly from the unique characteristics of the patented invention."

This matters for the '738 because the same AURA product line is the likely commercial-success story, and the same nexus defects (unclaimed feature bundling; no demonstrated link between the claimed "rule for behavior"/"observe operation" logic and demand) would likely recur. I would expect any '738 obviousness challenge to press this point.

---

7. Bottom line

Two mandatory qualifications:

1. No merits tribunal has ruled. IPR2024‑00947 was denied institution on § 325(d) (Nov. 19, 2024; Director Review affirmed Apr. 4, 2025). A denial on discretion is not a finding of non-obviousness, and it is not a finding of obviousness either. The § 325(d) denial does, however, mean the Patent Owner's substantive positions were never tested adversarially at the Board on this patent.
2. References I could not independently verify. My searches returned the identities and dates of Heddebaut, Das, Ackerman, Hungate, Molisch, Nikitin, Fullerton, Katz, Suzuki, Arthur, Fera, Ghaly and Kane, but did not return their full disclosures except for Kane's abstract and Grisham's and Knott's key passages. Any mapping of Ackerman, Hungate, or Das to specific limitations is reported as the petition asserted it, not as independently confirmed by me. If this analysis is going to be relied on, those three references should be pulled and read directly. I do not claim knowledge of their disclosure beyond what is stated above.

---

Sources: U.S. Pat. No. 9,731,738 (https://patents.google.com/patent/[US9731738](/patent/US9731738)/en); PTAB Decision Denying Institution, IPR2024‑00947 (https://www.uspto.gov/sites/default/files/documents/ipr2024_00947_paper_16_.pdf); IPR2024‑00947 Petition and Exhibit List (https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1556106](/patent/1556106)/download-documents); Unified Patents case profile (https://ipverse.greyb.com/ptab-web/cases/case-details/IPR2024-00947); IPR on the related '131/'227 patents (https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1550914](/patent/1550914)/download-documents); Metrom Rail, LLC v. Siemens Mobility, Inc., No. 24‑2223 (Fed. Cir. May 11, 2026) (https://www.courtlistener.com/opinion/[10856969](/patent/10856969)/metrom-rail-llc-v-siemens-mobility-inc/); U.S. Pat. No. 9,043,131 (https://patentimages.storage.googleapis.com/36/d7/9f/afe31b8e363369/[US9043131](/patent/US9043131).pdf); Metrom Rail AURA product literature (https://metrom-rail.com/filebin/images/products/pdf/AURA_ProdSht_0124a.pdf, https://metrom-rail.com/filebin/images/products/pdf/AURA_PTCS.pdf); McAndrews press release (https://www.mcandrews-ip.com/mcandrews-secures-victory-for-client-metrom-rail-llc/).