Doctoral Degrees (Civil Engineering)

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Browsing Doctoral Degrees (Civil Engineering) by Author "Ambunda, Otumuna Robert"

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    Developing road crash prediction models to investigate the combination of effects of roadway conditions on national rural road crashes
    (2021-12) Ambunda, Otumuna Robert; Sinclair, Marion; Stellenbosch University. Faculty of Engineeing. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: Namibia is faced with the reality of an increase in the frequency of fatal and serious injury (FSI) crashes on national rural roads, despite the roadway infrastructure considered to be in good condition. More so, an increase in roadway traffic volume has subsequently worsened the crash risk levels for road users. To address this issue, the study was aimed at exploring the combinatorial effects of road and traffic characteristics of national rural roads in Namibia on fatal and serious injury crashes and the crash risk factors preceding the crashes. The main crash dataset, for the period 2012 to 2016, and supplemented roadway design data were provided by the Namibian National Road Safety Council (NRSC) and Roads Authority (RA) respectively. The study applied novel robust multiple linear regression models and cluster analysis to the aggregated study dataset. The study objectives were five-fold. The first objective of the study was to examine the profiles and risk factors attributed to national rural road crashes. The goal of this objective was to create a new basis to assess the relationship between road characteristics and driver risk factors preceding road crashes. This will serve as a basis for crash risk factor comparisons for any future studies. The second objective was to identify high risk traffic crash locations on the different national rural road classifications. The third objective was to assess the distribution of fatal and serious injury crashes across the national rural road network by applying the KDE spatial analysis technique. The fourth objective was to investigate the compliance of the rural road design characteristics with road design guidelines. Recommendations on the suitability of the design standards were based on the results of the first three and fifth objectives of the study. The fifth objective of the study was to develop novel road crash predictive models; calibrated and within the context of the Namibian national rural road environment. This objective was underpinned by the other four objectives in examining the spatial distribution of the road crashes, the response of crash distribution to design compliance levels and the sensitivity of the novel CPMs to changes in design characteristics. The insights from the study will have a long-standing and significant impact on rural road safety in Sub- Saharan Africa (SSA) and beyond. The study has highlighted multiple areas in the rural road safety system that urgently need to be addressed to provide a safer environment for road users on the network. As Namibia prepares the new Decade of Action (DoA) Strategic Plan for the year 2021 to 2030, the insights from the study provide a backbone on which rural road safety can be addressed in the DoA, with an approach that is aimed at reducing and eliminating so-called latent gaps in the components of a safe road system.