Low Level Function
9.1.2 Process Priority Request

Overview

This Function shall be capable of providing the following facilities:

(1) The ability to provide a mechanism through which Vehicles can be provided with priority through the urban road network.
(2) When a request is received via the Driver interface functionality, the ability to request that a green wave route is created by the Provide Traveller Journey Assistance functionality.
(3) The ability to obtain the current location of the Vehicle from its own sensors and use it in the priority request, as well as including the destination, plus any compulsory "way points" that the Driver has specified when making the request.
(4) When the route is received, the ability to send the data to the Manage Traffic functionality to enable the requested priority to be implemented, adjusting the request according to the number of signalised road junctions involved and sending a local priority request if only one junction is involved.
(5) The ability to send the responses received from the Manage Traffic functionality (indicates success or failure of the priority request) to the Driver interface functionality for output to the Driver and to filter the data included in the responses so that anything that is not relevant to the Driver that made the priority request is removed.
(6) The ability to include the required average speed for each route segment in the data sent for output to the Driver when the response from the Manage Traffic functionality indicates that the priority request was successful.

Functional Requirements

(a) continuously monitor for the receipt of the data flow requesting vehicle priority is received
(b) when the data flow in (a) is received, determine the location of the vehicle and collect data about the vehicle from its systems
(c) use the data from (a) and (b) to send a request for a green wave to the Provide Green Wave Routes function
(d) when the input data flow providing the response to (c) is received, send the response data flow to the Driver Interface function
(e) if there are several signalised junctions in the route received in (d), send a green wave request to the Provide Urban Traffic Commands function
(f) when the result from (e) is received, send the green wave request response data flow to the Driver Interface function
(g) if there is only one signalised junction in the route received in (d) send a local priority request to the Output Stop&Go Commands function
(h) when the response to (g) is received, send the green wave request response data flow to the Driver Interface function
(h) if the data flow about vehicles priority operating is received, check that it will affect any of the vehicles to which priority is being given and if so send the other vehicle receiving priority data flow to the Driver Interface function

Diagrams

The Diagram(s) is (are) the diagram(s) where you can find the function :
  • DFD 9.1 Enable Other Vehicle Priority
  • Functional Tree of Area 9

    • Parent Higher Level Function

    Input logical dataflows

    Output logical dataflows

    User needs

    Number

    Description

    7.5.2.10
    The system shall be able to warn other vehicles that a green wave is in operation.
    7.5.2.2
    The system shall enable the driver of a host vehicle to request a series of green phases from traffic signals (i.e. a green wave) for the route that is about to be taken.
    7.5.2.3
    The system shall enable a traffic signal controller to receive a request for a green phase from an approaching vehicle; in the event that more than one conflicting request is received at the same time they shall be prioritised (e.g. emergency vehicles before private vehicles), possibly by the TCC operator.
    7.5.2.6
    The system shall enable the traffic signal controller to inform the driver, via an in-vehicle display, that a green phase will be available when the host vehicle arrives at that junction; this includes the ability to warn that a green phase is not possible.