A study has been carried out in order to investigate the influence of suspension and tyre modelling on the outputs predicted by vehicle handling simulations. The computer models have been generated using data for a Rover vehicle, for which instrumented track test measurements were also available. The results obtained from a high speed lane change manoeuvre have been used as a benchmark for comparison of the various computer modelling strategies. This investigation addresses two main areas. The first of these is the influence of suspension modelling on calculated outputs. The second and more complex area investigates the influence of models representing the effects of the tyres. In each case a primary aim has been to asess the accuracy of models which use a simplifed approach, reduce the number of model parameters and may hence be more amenable to vehicle and tyre design studies. Comparison of the results from this study indicate that for quite an extreme manoeuvre a relatively simple vehicle and tyre model can be used to carry out a simulation with a good level of accuracy. A sensitivity study has also been carried out to illustrate how the models respond to design changes for both vehicle and tyre parameters. The multibody systems analysis program ADAMS (Automatic Dynamic Analysis of Mechanical Systems) has been used to generate the models, formulate and solve the equations of motion, and postprocess the results. An initial literature survey has been carried out investigating this analysis discipline and its usage in vehicle dynamics. Previous work in the areas of vehicle handling sikulation, tyre theory, and computer modelling of both vehicles and tyres has also been studied. Initial investigations have been carried out looking at the modelling of the suspension systems and the steering system. Information from this phase has been used to provide inputs for a set of four full vehicle models ranging in complexity from a model where the suspensions are treated as lumped masses, a model where the suspensions are treated as swing arms, a model based on roll stiffness and a final detailed model which represents the suspension linkages as fitted on the vehicle. Of the three simple models it will be shown that the roll stiffness model is most suitable for further comparisons with the detailed linkage model, where aspects of tyre modelling are considered. Tyre testing has been carried out at SP Tyres UK Ltd. and at Coventry University. A set of FORTRAN subroutines, which interface with ADAMS, has been developed in association with a computer model of a tyre test rig to represent and validate the various tyre models. The provision of these tools forms part of a new system developed during this study and is referred to as the CUTyre System due to its origins at Coventry University. The tyre models compared include a well known and accurate model which requires up to fifty model parameters and a more simple model requiring only ten parameters. An interpolation method is also used as a benchmark for the comparisons. To the author's knowledge the work described in this thesis can be considered to make an original contribition to the body of knowledge involving the application of multibody systems analysis in vehicle dynamics by: (i) providing a detailed comparison of vechicle suspension modelling strategies with the ADAMS program, (ii) developing a tyre modelling and validation tool which can interface directly with the ADAMS software, (iii) providing a comparison between a sophisticated and a simple tyre model in ADAMS. Of particular significance is the assessment of the influence of the tyre models on simulation outputs and not just shape of the tyre force and moment curves.

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Past research indicated that driver information requirements were varied (e. g. Spyridakis et al., 1991) and the motorists population cannot be consider homogeneous in terms of information requirements (e. g. Haselkorn et al., 1991). Some of the previous studies even suggestedth at before the so-called intelligent systemsg o into production, several unresolved issues concerning what kind of information drivers require need to be resolved. Thus, this thesis is interested in exploring several human factors issues concerning drivers; ' information requirements. First, the study is trying to provide at least a general picture of what kind of information is suitable to be presented to drivers in certain types of journey. Secondly, the thesis is interested in exploring the suitable timing and mode to present the required information to the target audiences. Besides the aforementioned human factors issues, this research also investigated how drivers plan their routes and find their way in unfamiliar destinations. The study is also interested in examining criteria used by drivers in choosing a route to their intended destination. Finally, this thesis aims to measure respondents' behavioral responses when they were given several traffic messages on congestion while commuting to and from work. The results also revealed that local drivers used more than one strategy for route planning and wayfinding in unfamiliar locations. Maps were the main strategy used by most of the respondents who participated in this study. Other strategies used by respondents were asking a passer-by, relying on memory and going without preparation. Apart from that, this study also demonstrated the difficulty in arriving at a general conclusion concerning the appropriate criteria that drivers would use in selecting a route for different trips. Local drivers would use a variety types of criteria in order to choose a route to a particular destination. However, the thesis identifies that drivers mainly employed three types of criteria in selecting a route to a particular destination. These criteria were safety, saving mileage and avoiding congested routes The final study (Study 3) was interested in extending the results of both studies I and 2 particularly the presentationo f congestionm essagesto its end users,i . e. motorists. An experiment was conducted to investigate drivers' response towards the presentation of traffic messagesa bout congestion.T he findings clearly supportedp revious work that found different types of information are likely to elicit different kind of responses from the drivers. In addition, local drivers also had ideas about the design of future traffic messages on congestion. For example, the need to have a quick solution when faced with the problem, e. g. offer alternate route; the need to have information on travel time if they decided to use the alternate route recommended by the systems; and some of the messages should be given as early as possible to serve as pre-trip advanced warning to drivers. The findings clearly demonstrated the preference for having more information rather than less.

Accurate measurement of a vehicle's resistance to motion on a road (the 'road load'), and the separation of this resistive force into its contributory components is of fundamental importance to generate the data required for vehicle performance assessment, the calibration of a modem chassis dynamometer and for comparing the drag of different vehicles or vehicle configurations. Established methods of determining road load on a test track are the coastdown and steady state torque tests, but environmental variability (largely due to ambient wind) and differences in the vehicle operating conditions cause wide variation in the results. This thesis describes a comprehensive study into methods of acquiring and analysing road load data at a test track. A mathematical model of the vehicle travelling in a straight line, in the presence of ambient wind, is developed and may be applied to measured data obtained in both the coastdown and the steady state test modes. The model includes the aerodynamic drag, tyre losses, transmission and un-driven wheel losses and the variation of aerodynamic drag with yaw angle. Experimental data obtained at a test track, using advanced instrumentation (including on-board anemometry and wheel torque meters) are analysed to obtain estimates of the coefficients in the road load equation. The results from an initial study demonstrate the importance of measuring the local wind at the test vehicle and the transmission losses if the total drag is to be accurately measured and separated into its contributory components. The coastdown method is shown to be more accurate and repeatable than the steady state method, and is therefore used as the basis of an advanced test procedure. Up to four coefficients can be determined from the coastdown data using a parameter optimisation routine. This routine fits the mathematical model to the measured coastdown profile to obtain estimates of the road load coefficients including the variation of aerodynamic drag coefficient with yaw angle. Results using this analytical method show that all four coefficients can be determined from coastdown data if there is sufficient ambient wind, and hence lay the basis for an advanced test method using only data from track tests. Constrained methods, where one or more of the parameters is fixed, can be used to investigate a single source of drag. The reduction in the total number of tests required to achieve an acceptable level of accuracy in the variable coefficients when using the constrained method is demonstrated.

This research develops a conceptual model of freight modal choice in which the basic unit of analysis is the socio-organisational group. Research into freight modal choice at the level of the firm has tended to disregard the nature of human choice and to assume that modal choice can be explained in terms of technological phenomena or cost relationships. There is also a tendency to equate the modal choice of organisational members with the modal use of firms. The approach adopted in this work is to accept that there are different interest groups within shipper firms and that such groups may not necessarily form a consensus of opinion about freight model choice. It is assumed that different socia-organisational groups may form different implicit theories about transport systems. Such an approach is called the social perceptual approach. The conceptual modal is converted into an operational model and an empirical investigation is undertaken into the area of modal choice between air freight transport end surface less than full load freight transport from the United Kingdom to Western Europe. In particular, the standpoint of shipping managers (managers responsible for arranging international freight transport in exporting companies) is examined vis-a-vis certain normative approaches such as the through transport concept.

In this work. an attempt has been made to develop a programming package for ride analysis of off-road vehicles based upon a finite-element formulation of vehicle suspension systems. Mathematical modelling of generalised suspension systems has been carried out with several non-linear aspects being investigated and implemented in the programming package. such as large deflection. non-linear characteristics of springs and dampers. bump stops and wheel separation. Different types of soi 1 have been considered together with an appropriate modelling of vehicle tracks. Several methods for time integration of dynamic equations have been investigated so as to deal wi th numerical instabi 1 i ty problems expected for off-road suspension systems which often have 'stiff' differential equations of motion. Three ride analysis criteria have also been considered in the programming package. Several case studies have been analysed using the developed programming package. They consist of two simple case studies with known analytical solutions. an existing wheeled off-road vehicle with published analog computer resul t s , and an off-road tracked vehicle wi th known experimental results. The package has been validated and proved to be an acceptable tool for the ride analysis of off-road vehicles. within the approximating assumptions considered. Several measures for future development have also been suggested.