# Quality of Service Criteria in Integrated Passenger Transport Systems: An Overview
## 5 Defining Quality of Service Criteria in Integrated Passenger Transport Systems  
Quality has a fundamental influence on passenger transport services. The main objective of transport is to satisfy customers. Assessing the quality of public transport services involves evaluating various aspects to ensure they meet customers' needs efficiently, safely and comfortably. From the passenger's point of view, it is necessary to assess the availability of travelling opportunities between selected points on the network.  
An IPTS is a more comprehensive approach to passenger transport that involves various transport modes and aims to provide customers with seamless, coordinated and convenient travel options [40]. Due to its main characteristics (unified fare system, integrated and harmonised timetable, unified ticketing system and information system) and various transport modes, an IPTS should primarily specify QoS based on the transport network instead of analysing PPT modes separately.  
Because of its complexity, an IPTS should value and prioritise QoS criteria differently than PPT. The 8 categories of criteria, which represent customers' views of provided service for PPT and an IPTS, are contained in Table 1.  
By realising the advantages of a well-established IPTS, the two categories that describe the transfer offer more generally should be based on IPTS instead of a basic PPT system. The travel offer from origin to destination is, in principle, affected by travel information, travel time, number of transfers (changing the transport means) and number of travel opportunities [42].  
Information is one of the detailed category contributing to public transport QoS. Many trips require various transport modes to accomplish the journey destination, so information must cover the entire \"door to door\" journey. This perceptual dimension indicates that the customer must adapt to the daily changing situations during his journey. Technological possibilities allow passengers to adapt to different travel scenarios [43]. Due to the concept of the IPTS organisation, every transport mode should provide travel information for users. Onwards, integration of travel information must provide travel information in the whole network in order to simplify transfers to other PPT modes. Thus, integrated travel information should be a detailed category of the QoS in the IPTS service.  
An IPTS network consists of numerous transport providers, and the journeys may involve a transfer between transport modes. The customer experience of the total travel time is based on the overall journey, including transfers between PPT modes. In the end, the total travel time of the entire journey is relevant for the customer. For a journey with multiple transport modes, the total travel time includes the waiting time at the origin stop, the first in-vehicle time, transfer (walking) times between modes, waiting time at the next stop and the next in-vehicle time of the journey [44]. As a result, total travel time in IPTS represents a more complex and detailed category of QoS.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Category** & **PPT/IPTS Offer** & **PPT Service** & **IPTS Service** \\ \hline
1. & general & availability & network \\
2. & general & accessibility & internal interface \\
3. & detailed & information & integrated travel \\
4. & detailed & time & total travel time \\
5. & detailed & customer care & customer care \\
6. & detailed & comfort & comfort \\
7. & detailed & security & security \\
8. & environmental & environmental impact & environmental impact \\ \hline \end{tabular}
\end{table}
Table 1: Quality of service in public passenger transport services [41].