IP Law Daily, PATENT—Fed. Cir.: PTAB’s invalidation of railroad collision-avoidance patent claims affirmed; surviving claims also obvious, (May 12, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

Prior art references disclosed the claimed ultra-wideband and GPS-based train tracking technology.

In a non-precedential disposition, the U.S. Court of Appeals for the Federal Circuit has affirmed in part and reversed in part Patent Trial and Appeal Board (PTAB) decisions finding all claims of two railroad collision-avoidance patents owned by Metrom Rail, LLC unpatentable as obvious. The appellate court agreed that prior art references disclosed the claimed collision-avoidance systems using ultra wideband (UWB) sensing technology and GPS-based location tracking. Further, the Federal Circuit reversed the Board’s determination that several claims of one patent survived review, concluding that the Board adopted an incorrect construction of the phrase “data representing the separation distance” (Metrom Rail, LLC v. Siemens Mobility, Inc., No. 24-2223 (Fed. Cir. May 11, 2026)).

IPR proceedings. Patent owner Metrom Rail, LLC, owned U.S. Patent Nos. 9,043,131 (the ’131 patent) and 8,812,227 (the ’227 patent), which related to railroad collision-avoidance systems. Siemens Mobility, Inc., Hitachi Rail GTS USA Inc., Humatics Corp., and Piper Networks, Inc. jointly petitioned for inter partes review (IPR) of both patents. The petitions asserted that all challenged claims were obvious over combinations of prior art references describing train collision-avoidance systems using UWB sensing technology and GPS functionality.

The ’131 and ’227 patents shared a common specification and claimed priority to May 19, 2011. The patents described collision-avoidance systems designed to track the location and speed of rail vehicles and determine the distance between them over varying terrain conditions. The systems used UWB sensing technology and GPS units to monitor train movement and warn operators of potential collisions.

The primary prior art reference relied upon in the IPRs was U.S. Patent No. 6,759,948 (“Grisham”), which disclosed a railroad collision-avoidance system using UWB sensing technology. The petitioners also relied on International Publication No. WO 03/009254 A1 (“Nixon”) for GPS-based functionality and U.S. Patent No. 8,874,359 (“Douglas”) for location-tracking features.

The PTAB determined that all claims of the ’227 patent and claims 1–16 of the ’131 patent were unpatentable as obvious. However, it concluded that claims 17–20 of the ’131 patent were not unpatentable because Grisham allegedly failed to disclose a limitation requiring “a first wireless communications antenna operable to send and receive data representing the separation distance over the air.” Metrom appealed the Board’s adverse rulings, while the petitioners cross-appealed the Board’s determination upholding claims 17–20.

Secondary considerations. On appeal, Metrom argued that the Board improperly discounted evidence of secondary considerations of nonobviousness tied to its AURA CAS product, a collision-avoidance system using UWB and GPS technology. Reviewing the Board’s findings for substantial evidence, the Federal Circuit rejected that argument.

Citing Fox Factory, Inc. v. SRAM, LLC, 944 F.3d 1366 (Fed. Cir. 2019), the court reiterated that a patentee is entitled to a presumption of nexus only if the commercial product is coextensive with the claimed invention. The Board found that the AURA CAS product included important unclaimed features, including machine function monitoring and remote data reporting. Because those features were not insignificant, the Board properly refused to apply a presumption of nexus.

The Federal Circuit also agreed that Metrom failed to show that any alleged commercial success resulted directly from the unique characteristics of the patented invention. Although Metrom’s expert asserted that the claimed features drove demand for AURA CAS, the expert did not identify any inventive characteristics that distinguish the system from prior art.

Single-reference obviousness. Metrom next challenged the Board’s determination that claim 1 of each patent was obvious over Grisham alone. The Federal Circuit rejected those arguments, noting that Metrom failed to raise timely substantive challenges before the Board. Instead, the patent owner first presented additional arguments in sur-replies.

Citing Rembrandt Diagnostics, LP v. Alere, Inc., 76 F.4th 1376 (Fed. Cir. 2023), the Federal Circuit held that the Board acted within its discretion in declining to consider untimely patentability theories. Because Metrom forfeited those arguments, the court affirmed the Board’s obviousness findings for claim 1 of both patents.

Location tracking claims. Metrom also argued that claims directed to a “central tracking unit” capable of tracking vehicle locations required more precise location tracking than disclosed by Douglas. The Federal Circuit disagreed.

The Board found that Douglas disclosed systems capable of tracking train locations relative to track links and switching points. According to the Federal Circuit, the challenged claims did not require any particular degree of precision. As a result, Douglas adequately disclosed the claimed “track a location” limitation, supporting the Board’s obviousness determination for claims 2–4 of both patents.

Motivation to combine. The Federal Circuit further upheld the Board’s determination that an ordinarily skilled artisan would have been motivated to combine Grisham’s UWB-based system with Nixon’s GPS technology.

Metrom argued that UWB radios could create interference problems and that the Board improperly relied on conclusory expert testimony. The Federal Circuit disagreed, pointing to evidence that UWB technology had a limited transmission range and that GPS functionality could improve train positioning accuracy. Nixon expressly disclosed collision-avoidance systems applicable to trains that combine GPS and UWB technology. The Board’s motivation-to-combine findings were therefore supported by substantial evidence.

Claims 17–20. The petitioners’ cross-appeal focused on claims 17–20 of the ’131 patent. The Board had concluded that Grisham did not disclose transmitting “data representing the separation distance over the air.”

The Federal Circuit reversed. The appellate court determined that the Board adopted an incorrect construction of the disputed phrase. According to the Federal Circuit, the phrase encompassed data used in the time-of-flight calculation that determined separation distance, not merely an already-computed separation distance. Because Grisham undisputedly disclosed transmitting time-of-flight data over the air between locomotives, the court held that the reference satisfied the disputed claim limitation.

The court therefore concluded that claims 17–20 were also unpatentable as obvious.

Partial dissent. Circuit Judge Richard G. Taranto concurred in part and dissented in part from the majority’s decision reversing the Board’s ruling on claims 17–20 of the ’131 patent. Judge Taranto argued that the majority improperly relied on a new claim-construction theory that the petitioners had not adequately presented either before the PTAB or on appeal. According to the dissent, the petitioners challenged the Board’s reading of the prior art reference Grisham, but did not sufficiently argue that signals used in the time-of-flight calculation themselves constituted “data representing the separation distance” under the proper construction of claim limitation 17C. Judge Taranto maintained that the principles of party presentation and forfeiture should have prevented the Federal Circuit from reversing the Board on a theory that the parties had not fully developed.

Disposition. Finally, the Federal Circuit affirmed the Board’s findings that all claims of the ’227 patent and claims 1–16 of the ’131 patent were unpatentable as obvious, reversed the Board’s determination sustaining claims 17–20 of the ’131 patent, and awarded costs to the appellees/cross-appellants.

The Case is No. 24-2223.

Judge: Dyk, T.

Attorneys: Gregory Schodde (McAndrews, Held & Malloy, Ltd.) for Metrom Rail, LLC. Mark Michael Supko (Crowell & Moring, LLP) for Siemens Mobility, Inc.

Companies: Metrom Rail, LLC; Siemens Mobility, Inc.

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