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Grade-crossing motorist warning system
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Patent number 3,963,202
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Issue date Jun 15, 1976
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The United States of America as represented by the Secretary of the Departmen...
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John B. Hopkins
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B61 - RAILWAYS
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3927852
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Patent number 3,927,852
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Issue date Dec 23, 1975
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B61 - RAILWAYS
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3909632
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Patent number 3,909,632
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Issue date Sep 30, 1975
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B61 - RAILWAYS
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3753073
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Patent number 3,753,073
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Issue date Aug 14, 1973
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B61 - RAILWAYS
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3734434
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Patent number 3,734,434
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Issue date May 22, 1973
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B61 - RAILWAYS
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3694695
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Patent number 3,694,695
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Issue date Sep 26, 1972
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H03 - BASIC ELECTRONIC CIRCUITRY
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3631392
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Patent number 3,631,392
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Issue date Dec 28, 1971
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G08 - SIGNALLING
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3569730
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Patent number 3,569,730
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Issue date Mar 9, 1971
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B61 - RAILWAYS
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3471689
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Patent number 3,471,689
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Issue date Oct 7, 1969
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B61 - RAILWAYS
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3390304
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Patent number 3,390,304
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Issue date Jun 25, 1968
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B61 - RAILWAYS
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3389330
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Patent number 3,389,330
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Issue date Jun 18, 1968
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H03 - BASIC ELECTRONIC CIRCUITRY
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3267281
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Patent number 3,267,281
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Issue date Aug 16, 1966
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B61 - RAILWAYS
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3258653
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Patent number 3,258,653
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Issue date Jun 28, 1966
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B61 - RAILWAYS
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3176126
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Patent number 3,176,126
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Issue date Mar 30, 1965
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B61 - RAILWAYS
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3004150
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Patent number 3,004,150
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Issue date Oct 10, 1961
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B61 - RAILWAYS
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2869045
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Patent number 2,869,045
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Issue date Jan 13, 1959
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B61 - RAILWAYS
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2220484
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Patent number 2,220,484
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Issue date Nov 5, 1940
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B61 - RAILWAYS
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2213377
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Patent number 2,213,377
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Issue date Sep 3, 1940
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B61 - RAILWAYS
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2210052
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Patent number 2,210,052
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Issue date Aug 6, 1940
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B61 - RAILWAYS