The project concerns the development of new paradigms and models for ATIS (Advanced Travellers Information Systems). ATIS are a field of application of increasing interest, but most of the research in last years has been done on operational technological aspects, rather than on theoretical traffic and transportation engineering aspects.
Most of the current tools and application are able to supply to drivers instantaneous and punctual information; they mainly consist in technological applications able to distribute (by using a wide variety of transmission means channels) only the information that is directly gathered for the traffic system via monitoring devices, without the possibility of estimating traffic conditions of the traffic network's links where monitoring devices are not installed and with no possibility of forecasting traffic information. The project has been conceived to fill this gap.
The project aims at deeply investigating the potentialities to provide predictive information on the whole traffic network that will be actually experimented by the travellers because consistent with the reactions that they will have with respect to the information itself. None of the current modelling approaches and tools is able to produce such information. Advanced Travellers Information Systems are a field of application in transportation whose importance has been widely recognised in the last decades. However, most of the today modelling and applicative tools fail in fully fitting the desired characteristics of really effective ATIS. The state-of-the-art in ATIS is as follows:
- most of the current tools and applications are able to supply the drivers instantaneous and punctual information; they mainly consist in technological applications able to distribute (by using a wide variety of transmission means channels) only the information that is directly gathered for the traffic system via monitoring devices, without the possibility of estimating traffic conditions on links of the traffic network where monitoring devices are not installed and without the possibility of forecasting traffic information;
- some of the most advanced modelling tools (even if not widely applied) are able to extend the information directly gathered from the monitoring devices in order to cover also non-monitored links of the traffic network and/or to produce forecasts for the traffic conditions; they are, at least in theory, able to produce system and/or predictive information;
- none of the current modelling tools is able to produce accurate information, that is predictive information on the whole traffic network that will be actually experimented by the travellers because consistent with the reactions that they will have with respect to the information itself.
In order to move the current theory and practice of ATIS forward to the desired aim of an accurate information system, a strong innovation has to be introduced with regard to dynamic traffic simulation and forecasting models and also to enabling interdisciplinary issues. So far, the development of effective models for ATIS has been negatively influenced by a crucial misunderstanding, based on the assumption that information from ATIS could induce travellers to behave according to system-optimum or, which is similar, could create the conditions for the coincidence of users-optimum
An innovative modelling approach has been investigated by the project. It is based on the assumption that travellers' compliance to ATIS is elastic: travellers update their compliance within a more general day-to-day dynamic process, where the compliance depends on the accuracy of the information supplied in previous days.
Moreover, the effect of ATIS is considered, for equipped travellers, to be on choice-upgrading, rather than on utility-upgrading. Such an innovative approach allows to estimate the effects of different information strategies on both the dynamics of the traffic system and the evolution of travellers' compliance and satisfaction, as well as by simulating the convergence and stability properties of the simulation models both over the day-to-day dynamics and the within-day dynamics of the traffic systems. It also allows to develop effective information design models where several information strategies can be tested and the best one/s can be selected by simultaneously considering all consistent issues among information designing and travellers' reactions.
The project has shown that a new modelling approach, able to deal with explicit (and endogenous) travellers' compliance, allows to reach a better evaluation of ATIS applications. The main characteristic of innovative approaches to ATIS should consist in considering travellers' compliance to ATIS as to be elastic and updatable within a general day-to-day dynamic process, where the compliance depends on the accuracy of the information supplied in previous days. Such a result has been shown, in a first phase of the research, with respect to a simple test-network and through numerical applications.
It has been shown that in case of rigid compliance, the presence of ATIS seems to reduce traffic system's oscillations with respect to the absence of ATIS in an effective way, but that the assumed compliance in only hypothetical and cannot be reached due to the inconsistency of the supplied information. The case of elastic compliance is very different. In this case the traffic system increases its stability in presence of accurate information or, in case of large market penetration of the ATIS system, in the case where inaccuracy is limited to small values. In a second phase of the project, the results have been generalised, via theoretical speculations, for general networks. The stability of the process has been investigated with reference to local properties, provided that the theoretical investigation of global stability is not suitable in general cases. It can be proven that it can be written according to the Jacobian matrix of the dynamic process, computed at the equilibrium point where the local stability is investigated, in case of elastic compliance and accurate information strategy.
The analysis of this Jacobian matrix shows that, in case of accurate information strategies and in case of a correct simulation model, which explicitly simulate compliance elasticity with respect to information accuracy, the stability region of the equilibrium condition of the dynamic process monotonically increases with increasing market penetration. This is a desired result for ATIS applications and contradicts some common results that, incorrectly, have show instability phenomena in case of increasing ATIS market penetration. Such a not negligible difference is due to the lack of other models to explicitly simulate compliance to information and to the fact that most of the previous models do not deal with accurate information.
Information and communication technologies (ICT) applied to transportation are a challenging and interesting field of research and application development. This can lead to a more efficient use of existing transportation infrastructures and systems, according to several sustainability paradigms. However, at least in the field of ATIS (Advanced Travellers Information Systems), the research and application needs are not only of technological nature. Transportation and traffic modeling aspects are of crucial importance and should be deeper investigated in theoretical ways and carefully implemented in operative applications. In the case that ATIS applications were not based on solid theoretical foundations, they could likely lead to traffic system instability. It should be important to promote actions at international level in order to assess good practice and methodologies for the study of ATIS applications.