Urban design has splintered into increasingly narrow specialist disciplines since the mid Twentieth Century. Traffic engineers, statutory planners, civil engineers, landscape architects and architects each make specific but isolated contributions to urban design frameworks. Each consultant documents their position predominantly through text and two dimensional representations, occasionally with specious perspective images produced by a hand rendering specialist. This fragmented and sequential design approach inadequately addresses contemporary urban agendas, practice constraints or the potential of digital design techniques, particularly in light of increasing fears of an imminent environmental crisis and peak oil, and concerns for health, amenity and accommodating an increasingly urbanised population. The aim of my thesis is to identify and address disparities between contemporary urban design practice and society's prevailing urban agendas for integrated and sustainable cities. The hypothesis tested by my thesis is that the gulf between prevailing urban agendas of society and urban design can be reduced by developing a 'defragmented' design approach that uses rapid, parametric, four-dimensional, digital analysis and design techniques, which build upon software commonly available within the industry. This hypothesis has been tested in four ways: firstly through the analysis of urban agendas, design techniques and urban design paradigms, in both historic and contemporary contexts; secondly by identifying currently available technologies with the potential for adaptation and customisation; thirdly by development of new digital techniques; and finally by testing this defragmented approach on both simplified models and various case studies within an urban design practice as part of the embedded research program. Techniques I have developed and tested as part of the approach fit into four categories: firstly pedestrian connectivity - walkability and accessibility; secondly daylight amenity assessment; thirdly visual impact analysis assessing urban form visualisation, generation and composition; and finally feasibility modelling, including linked data yield analysis. I have evaluated the success of the approach in these studies with regard to practice constraints (time and budget) and contemporary society's pr evailing urban agendas. My rapid, defragmented design approach has resulted in new techniques shown to be used quickly and concurrently 'in-house' contributing to the urban design process, whilst meeting fee budgets and project deadlines. I have demonstrated that issues that are currently difficult to solve using the constraints of conventional planning techniques can be addressed more effectively than they are currently, whilst avoiding the considerable expense of specialised hardware/software or the appointment of additional consultants. My thesis concludes that the rapid, defragmented approach can demonstrably yield more synergistic urban design responses. The inherently flexible approach can be tailored for a myriad of different urban design scenarios, as well as potentially other disciplines. The defragmented approach can expand the realm of urban designers and increase their contribution in the generation and advocacy of sustainable planning policy and reduce the disparities between contemporary urban design practice and society's need for integrated and sustainable cities.