DD CEN ISO/TS 18234-5:2006 - Page 3

Traffic and travel information (TTI). TTI via transport protocol expert group (TPEG) data-streams. Public transport information (PTI) application | Status: Current

1 Scope This Technical Specification describes the Public Transport Information (PTI) Application, which is intended to cover all modes of public (i.e. collective) transport as well as inter-urban and intra-urban travel. The application is designed to allow the efficient and language independent delivery of public transport information directly from service provider to end-users. The term “application” is used in TPEG specifications to describe specific applications, such as in this case the public transport information application, which comprises three information containers: the message management container, the application event container and the TPEG-location container. The first two containers are fully described herein and the TPEG-location container is described in CEN ISO/TS 18234-6. Each TPEG Application (e.g. TPEG-PTI) is assigned a unique number that is called the Application IDentification (AID). An AID is defined whenever a new application is developed. The AID is used within the TPEG-Service and Network Information Application (CEN ISO/TS 18234-3) to indicate how to process TPEG content and allows routing of data to an appropriate Application decoder. AID = 0002 (hex) is assigned to the TPEG-PTI application, described in this specification. The TPEG-PTI application aims at describing “legs” of a journey also described as “rides” by other methodologies. However, it is important to note that TPEG-PTI is not limited to describing single services, because it also allows the more general description of route, service and area-wide problems. Public (or collective) transport information is usually consumed in one of four principle ways as follows:

• — Leader board information as used at stations or terminals;
• — A report on the state of a network;
• — The description of an individual service;
• — As a news flash report.

The elements needed to provide information for any one of the four end-user presentation modes are largely the same. The end-user focus of TPEG applications makes it useful to be able to mimic presentations, to which end-users are accustomed, for example a railway station indicator board. TPEG-PTI messages can therefore group data elements to present one of the following end-user presentation modes:

• — Incident message report;
• — Station/terminal information;
• — Route information;
• — Individual service information.

It is important to bear in mind that these end-user presentation modes are merely presentational aides; they have little to do with the content in the individual data elements. They do, however indicate how data elements must be grouped if a presentation in any of these views is intended. Unlike the TPEG-RTM application (CEN ISO/TS 18234-4), TPEG-PTI benefits from the nodal structure of public transport, making use of its discrete start, end and stopping points as well as being limited to fixed, be it real or virtual, routes.