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The following discusses how the National ITS Architecture provides the transportation service described by this service package. Each numbered item describes the operation of that portion of the service package identified with the corresponding number on the transaction set diagram.
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Equipment on the Roadway constantly monitors (traffic characteristics) highway-rail intersections. Vehicles may be tracked through the intersection. The equipment may detect when the intersection is blocked. When a blockage is detected, the Traffic Management Subsystem and the Wayside Equipment are notified (intersection blockage notification). Then the Traffic Management Subsystem will notify (hri advisories) the Rail Operations.
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The status of highway-rail intersection equipment (hri status) including both the current state and mode of operation and the current equipment condition is monitored by the Traffic Management Subsystem. The status can be requested (hri request) by the Traffic Management Subsystem or the Roadway Subsystem can send it when warranted, when a problem is detected or on a set interval.
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The Roadway equipment sends the status of the equipment including both the current state and mode of operation and the current equipment condition (hri operational status) to the Wayside Equipment.
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The Traffic Management Subsystem will control equipment (hri control data) at highway-rail intersections. The Traffic Management Subsystem may use surveillance cameras to monitor the intersections, gates or signals to control traffic through the intersections or signs or signals to display information on train crossings to travelers. The equipment on the Roadway can receive information on arriving trains (track status and arriving train information) from the Wayside Equipment. This information includes the current status of the tracks and when a train is expected and/or how long the train crossing is expected to last can be displayed for Drivers.
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Pedestrians can request right-of-way (crossing call) to cross a highway-rail intersection. Equipment on the roadway notifies the pedestrian when the request has been granted (crossing permission) via display, audio signal or other manner.
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Information (driver information) on the current or expected status of the tracks including message signs and flashing crossbucks can be displayed for Drivers. Alternatively, grade crossing status may be communicated to the vehicle using Field-Vehicle Communications (vehicle signage data).
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