Low Level Function
3.1.2.14.3 Output Lane & Speed Messages to Inter-urban Roads

Overview

This Function shall be capable of providing the following facilities:

(1) The ability to provide outputs that can only provide commands to Drivers using the inter-urban road network.
(2) The ability for these outputs to include regular speed and lane use commands and to supplement the outputs provided by other functionality.
(3) The ability to use several different technologies to provide the outputs but not through any in-vehicle technology as this will be provided separately.
(4) The ability to monitor all of the outputs and revisions to any already being output that are likely to give rise to inconsistent and incoherent messages being displayed to Drivers.

Functional Requirements

(a) continuously monitor for the arrival of the inter-urban speed l&s commands, inter-urban lane l&s commands, inter-urban speed display error, inter-urban incident warning l&s commands, inter-urban l&s display error and inter-urban speed being exceeded data flows
(b) when either the inter-urban speed l&s commands or inter-urban lane l&s commands data flows in (a) is received, output its contents to drivers in the inter-urban traffic l&s commands data flow
(c) also send the inter-urban l&s device status data flow to the Detect Inter-urban Traffic Violations function
(d) if the inter-urban speed being exceeded data flow is received in (a), output its contents (including the vehicle identity) to the driver in the vehicle above required inter-urban speeds data flow
(e) if for any reason the actions in (b) or (d) fail then send a device failed indication in the inter-urban device status data flow to the Detect Inter-urban Traffic Violations function and the inter-urban traffic management l&s response data flow to the Implement Inter-urban Traffic Commands function
(f) the contents of the outputs in (b) shall be monitored and revisions provided to any that would generate inconsistent or incoherent messages being displayed to drivers
(g) if either the inter-urban l&s display error or inter-urban speed display error data flows are received, check their contents to see if a difference has been found
(h) if a difference is found (f) then again send a device failed indication in the inter-urban device status data flow to the Detect Inter-urban Traffic Violations function and the inter-urban traffic management l&s response data flow to the Evaluate Need for Equipment Maintenance function.

Diagrams

The Diagram(s) is (are) the diagram(s) where you can find the function :
  • DFD 3.1.2.14 Implement Inter-urban Management Traffic Strategy
  • Functional tree 3.1

    • Parent Higher Level Function

    Input logical dataflows

    Output logical dataflows

    User needs

    Number

    Description

    7.1.0.11
    The system shall be able to manage traffic in all or part of the road network using a methodology that is appropriate for motorways, e.g. no junctions and pedestrian facilities, but with lane use management.
    7.1.0.2
    The system shall be able to implement identified control strategies that conform with specified policy.
    7.1.0.3
    The system shall not do anything to reduce road safety.
    7.1.0.5
    The system shall manage road traffic in such a way that congestion (travel time) may be reduced.
    7.1.3.4
    The system shall be able to activate control devices (e.g. traffic lights, VMS), either individually or in groups.
    7.1.4.5
    The system shall be able to provide priority to selected travellers (e.g. PT, emergency vehicles, cycles, pedestrians) through the road network, including on motorways (when applicable).
    7.1.4.8
    The system shall be able to provide co-ordinated traffic management operations during periods of mass movement across (many) regions.
    7.1.4.9
    The system shall be able to provide specific traffic management for exceptional vehicles (e.g. very dangerous cargo, wide loads, etc.).
    7.1.5.1
    The system shall be able to provide control measures to protect road maintenance work and workers.
    7.1.5.2
    The system shall be able to command drivers to change lanes on multi-lane roads.
    7.1.5.3
    The system shall be able to change the direction of traffic flow on a some or all of the lanes on a carriageway in an orderly manner so that it does not create a safety hazard to any road user.
    7.1.5.5
    The system shall be able to close roads and advise drivers of a suitable diversionary route for a period of time.
    7.1.7.1
    The system shall be able to show the maximum authorised speed of vehicles on selected carriageways to be shown to drivers.
    7.1.7.2
    The system shall be able to set variable speed limits on parts of the road network.
    7.4.4.10
    The system shall enable the TCC to display safety-related information (e.g. legal speed limit, recommended speed limit) to drivers via a road-side device.
    7.4.4.12
    The system shall be able to compare the reported speed of a vehicle with the current legal speed limit and display a warning to the driver, via a road-side device, if its current speed is greater than the legal speed limit.
    7.4.4.14
    The system shall be able to compare the reported speed of a vehicle with the current recommended speed limit and display a warning to the driver, via a road-side device, if its current speed is greater than the recommended speed limit.
    7.4.4.6
    The system shall enable the driver of the host vehicle, via an in-vehicle device, to receive safety-related information (e.g. legal speed limit, recommended speed limit) from a road-side device.
    7.4.4.8
    The system shall be able provide recommended speed limits from outside the vehicle, and to confirm that they are consistent with the limits that have been sent directly to that vehicle.
    7.4.4.9
    The system shall enable a road-side device to display safety-related information (e.g. legal speed limit, recommended speed limit) to drivers via a road-side device.
    7.4.8.9
    The system shall enable the driver of the host vehicle to be advised, via an in-vehicle device, not to enter a zone defined by virtual cones.
    7.5.1.5
    The system shall be able to manage the traffic in an area using a number of local semi-autonomous traffic management units, whose rules can be modified when required.