  This paper investigates the performance, in terms of choice probabilities and
correlations, of existing and new specifications of closed-form route choice
models with flexible correlation patterns, namely the Link Nested Logit (LNL),
the Paired Combinatorial Logit (PCL) and the more recent Combination of Nested
Logit (CoNL) models. Following a consolidated track in the literature, choice
probabilities and correlations of the Multinomial Probit (MNP) model by
(Daganzo and Sheffi, 1977) are taken as target. Laboratory experiments on
small/medium-size networks are illustrated, also leveraging a procedure for
practical calculation of correlations of any GEV models, proposed by (Marzano
2014). Results show that models with inherent limitations in the coverage of
the domain of feasible correlations yield unsatisfactory performance, whilst
the specifications of the CoNL proposed in the paper appear the best in fitting
both MNP correlations and probabilities. Performance of the models are
appreciably ameliorated by introducing lower bounds to the nesting parameters.
Overall, the paper provides guidance for the practical application of tested
models.
