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A number of methods are being undertaken in New Zealand to achieve sustainable land transport outcomes. Lower urban speeds (less than 50 km/h) are increasingly being used to improve safety, but may also contribute to other sustainable land transport outcomes. This research includes: a literature review, case studies, a survey of industry professionals and comparative analysis, to consider the potential effectiveness and efficiency of reducing urban speeds1 to achieve sustainable land transport outcomes. There is reasonable consistency between the findings of the survey, case studies and literature review. The key areas of difference relate to the survey responses potentially under-estimating political and public support for reducing speeds. The responses also over-estimate the current contribution of industry knowledge, and the adverse effects of travel times, vehicle emissions, and fuel usage. In respect to efficiency, reducing urban speeds can be successfully implemented in New Zealand, time and cost requirements are achievable, and legislation is permissive, but additional guidance and industry knowledge is required. Political and public opinions are difficult to determine but there is nothing to suggest that there is widespread opposition to reducing urban speeds, particularly in residential, high pedestrian and business areas. In respect to effectiveness, reducing urban speeds can contribute to improving: safety, public health, accessibility, integrated urban form, environmental sustainability2 and economic development. The impact of increased travel times on functional transport networks is likely to result in some adverse effects, but these are not likely to be significant. Compared to the provision of walking and cycling infrastructure, from the information available, reducing urban speeds is considered to be at least as effective at achieving sustainable land transport outcomes. Reducing urban speeds could also be as efficient, as provision of walking and cycling infrastructure, with more consistent political support, more guidance on the use of legislation, and once the level of industry knowledge improves.

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In the first part of this study, the dynamic behavior of a cracked rotating shaft with a rigid disk is analyzed, with an ideal and a nonideal motor, passing through its critical speed. The shaft contains a single transverse crack that is assumed to be either completely open or completely closed at any given time, depending on the curvature of the shaft at the cross section containing the crack. Flexible, damped supports and overhangs with a mass at one end are included. The supports are modeled with elastic springs and dashpots. The influence of gyroscopic moments of the disk (with an ideal motor) is investigated. For a nonideal motor, there is an interaction between the shaft and the motor. Eccentricity of the disk, gravitational forces, and internal and external damping are included. The equations of motion and boundary conditions are derived by Hamilton's Principle. To eliminate the spatial dependence, the Extended Galerkin Method is applied. Longitudinal vibration, shear deformation and torsional vibration are neglected. In the second part of this study, the vibration suppression of a cracked, simply supported, rotating shaft with a rigid disk is discussed, with an ideal and a nonideal motor, passing through the critical speed. The use of a flexible internal constraint is introduced to suppress the vibration. By activating this additional internal support, the shaft is prevented from passing its critical speed. Transient motions occur at the time of activation or deactivation of the constraint. The maximum displacement of the shaft during acceleration (run-up) or deceleration (coast-down) can be reduced significantly by appropriate application of this flexible internal support. / Ph. D.