RESEARCH APPROACH ABOUT RELIABILITY OF ... - BHLS - HOME

level in quality and safety.
Each social component (service provider, users and community) has different needs and
therefore its own perception about the performances of the public transport system. The
service provider, according to a far-sighted business, also considers the customer and
community needs.
Usually, the public transport evaluations are developed to check the differences between
actual and past performances, obtaining a comprised evaluation during the time. The
evaluation can also be used to provide a benchmark with another company, or as the best
term of comparison. Obviously, the comparison needs to be founded on shared and
uniquely determined parameters.
In the field of specialized literature (Coelli et al., 1998; Russo and Varipapa, 2000;
Cantarella and Di Gangi, 2002), methods to analyze performances of public transport
companies are classified in two different types:
• parameters methods;
• non- parameters methods.
Actually, to analyze the performances of a public transport company the indicators
analysis is used, but there are also other methods like stochastic frontiers, econometric
models of production, and Data Envelopment Analysis whose parameters need to be
calibrated; further more these methods are being developed.
Between the indicators based methods it’s possible to distinguish two approaches: the first
assumes that just one indicator is enough to evaluate the system performances (Hensher,
1992; Obeng et al., 1992; Oum and Yu, 1995; Preston, 1995; Tretheway and Waters II,
1995). On the other hand, the second approach is based on the research of a set of
indicators to provide an analytical approach to analyze the system (OCSE, 1980; Miller et
al., 1984; Fielding et. al., 1985; MacDorman, 1988; Gattuso, 1992; Di Gangi and Montella,
1995; CERTU, 1997; Gattuso et al., 2002). This work focuses attention on the second
approach provided before and on the evaluation methods of indicators about
reliability/regularity/punctuality that are linked to both a service provider and users.
1.3 General approach to the evaluation of performance indicators
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