System and method for virtual block operational status control with long block time delay
US-12503145-B2 · Dec 23, 2025 · US
using track circuits
using track circuits · Cooperative Patent Classification (CPC)
Separating, mixing, shaping, printing, and transporting materials.
Related technology areas
Mapped technology topics for this CPC code.
| Metric | Value |
|---|---|
| CPC code | B61L3/221 |
| Official title | {using track circuits} |
| Display label | using track circuits |
| Total patents | 30 |
Filing trend
Year-over-year patent counts classified under this CPC code.
Filing activity over the last five years is rapidly declining.
| Year | Patents |
|---|---|
| 2016 | 2 |
| 2017 | 1 |
| 2018 | 2 |
| 2019 | 2 |
| 2021 | 7 |
| 2022 | 6 |
| 2023 | 4 |
| 2024 | 4 |
| 2025 | 2 |
Representative patents
Representative publications under this CPC code from precomputed stats, or recent filings when stats are unavailable.
System and method for virtual block stick circuits
US-2025033679-A1 · Jan 30, 2025 · US
System and method for virtual block stick circuits
US-12116028-B2 · Oct 15, 2024 · US
Railway detection system, railway infrastructure and method for detecting the presence of a railway vehicle
US-2024149931-A1 · May 9, 2024 · US
Method, system, computer-readable medium comprising software code for estimating parameters of railway track circuits, and related track circuit
US-11912322-B2 · Feb 27, 2024 · US
Railroad virtual track block system
US-2024001975-A1 · Jan 4, 2024 · US
Railroad virtual track block system
US-11767041-B2 · Sep 26, 2023 · US
System and method for virtual block operational status control with long block time delay
US-2023166780-A1 · Jun 1, 2023 · US
Wayside to railway vehicle communication method and device
US-11643122-B2 · May 9, 2023 · US
System and method for virtual block stick circuits
US-2023083828-A1 · Mar 16, 2023 · US
System and method for virtual block stick circuits
US-11511779-B2 · Nov 29, 2022 · US
Method, system, computer-readable medium comprising software code for estimating parameters of railway track circuits, and related track circuit
US-2022185351-A1 · Jun 16, 2022 · US
Railroad virtual track block system
US-2022089203-A1 · Mar 24, 2022 · US
System and method for virtual block stick circuits
US-2022032975-A1 · Feb 3, 2022 · US
Railroad virtual track block system
US-11230307-B2 · Jan 25, 2022 · US
Railroad virtual track block system
US-11230308-B2 · Jan 25, 2022 · US
Railroad virtual track block system
US-11104361-B2 · Aug 31, 2021 · US
Railroad virtual track block system
US-2021253147-A1 · Aug 19, 2021 · US
Railroad virtual track block system
US-2021253148-A1 · Aug 19, 2021 · US
Wayside to railway vehicle communication method and device
US-2021188335-A1 · Jun 24, 2021 · US
Frequently asked questions
Answers are generated from the same data shown on this page.
- What is CPC B61L3/221?
- CPC B61L3/221 is the Cooperative Patent Classification code for “using track circuits.”
- How many patents are filed under CPC B61L3/221 (using track circuits)?
- Our database includes 30 publications tagged with this CPC code.
- Is patent activity under CPC B61L3/221 growing?
- Publication counts under this code: 4 in 2024 vs 2 in 2025 (latest complete years).