Low Level Function
9.2.1 Provide Driver Interface for Bus Lanes

Overview

This Function shall be capable of providing the following facilities:

(1) A HMI through which the Driver can request the use of Bus Lanes and be informed about the success of the request.
(2) The HMI must require the Driver to provide the destination plus any "way points" for the route on which the use of Bus Lanes is being requested.

Functional Requirements

(a) continuously monitor for receipt of the bus lane use data flow
(b) when the data flow in (a) is received, process its contents and send them in the request bus lane use data flow and send it to the Manage Vehicles using Bus Lanes function
(c) continuously monitor for the bus lane use request result and other bus lane information data flows
(d) when the first data flow in (c) is received, output the contents to the driver in the bus lane request result data flow
(e) when the second data flow in (c) is received, check its contents and if it is a request for the destination, output this to the driver in the bus lane warning message data flow
(f) as a result of (e) continuously monitor for receipt of the destination for bus lane use data flow from the driver
(g) when the data flow in (f) is received, put its contents in the request bus lane use data flow and send it to the Manage Vehicles using Bus Lanes function
(h) if the second data flow in (c) contains warnings for the driver, output them to the driver in the bus lane warning message data flow.

Diagrams

The Diagram(s) is (are) the diagram(s) where you can find the function :
  • DFD 9.2 Provide Flexible Lane Allocation
  • Functional Tree of Area 9

    • Parent Higher Level Function

    Input logical dataflows

    Output logical dataflows

    User needs

    Number

    Description

    7.5.3.4
    The system shall enable the driver to set the destination of the host vehicle that wishes to use a bus lane, if this cannot be provided by the navigation system for lane use management.
    7.5.3.6
    The system shall inform the driver whether a licence has been granted to become an approved vehicle and, if so, for how long it will remain valid.
    7.5.3.7
    The system shall monitor the approved vehicles on the bus lanes and, if its licence has expired, that vehicle will be ordered to leave the bus lane at the end of that section.
    7.5.3.8
    The system shall monitor the usage of the bus lanes, and if a green wave cannot be sustained for a PT vehicle, then approved vehicles shall be ordered to leave the bus lane at the end of that section, and no further licences will be granted until suitable conditions are resumed.
    7.5.3.9
    The system shall monitor the congestion in each section of a bus lane and if a “critical/emergency” situation arises then approved vehicles shall be ordered to leave that section and the up-stream section(s) of bus lanes.