Developing road crash prediction models to investigate the combination of effects of roadway conditions on national rural road crashes

Ambunda, Otumuna Robert (2021-12)

Thesis (PhD)--Stellenbosch University, 2021.

Thesis

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.

AFRIKAANSE OPSOMMING: Namibië word gekonfronteer met die realiteit van ’n toename in die frekwensie van noodlottige en ernstige beserings (Fatal and Serious Injury, FSI) op plattelandse nasionale paaie, ondanks die feit dat die ryvlak infrastruktuur in ’n goeie toestand is. ’n Toename in die verkeersvolume het gevolglik ook die ongeluks-risiko vir padverbruikers vererger. Om hierdie kwessie aan te spreek, was die studie gerig op die navorsing van kombinatoriese effekte van pad- en verkeers-neigings van plattelandse nasionale paaie in Namibië op noodlottige en ernstige beserings-ongelukke en die risiko faktore wat die ongelukke voorafgaan. Die hoofbotsing-datastelsel vir die tydperk 2012 tot 2016, en aangevulde data van die ryvlak, is onderskeidelik deur die Namibiese Nasionale Padveiligheidsraad (Namibian National Road Safety Council, NRSC) en die Padowerheid (Roads Authority, RA) verskaf. Die studie het nuwe robuuste meervoudige lineêre regressiemodelle en groepsanalise toegepas op die geaggregeerde datastelsel. Die studie doelstellings was vyf-voudig. Die eerste doelstelling van die studie was om die profiel en risikofaktore wat toegeskryf word aan plattelandse nasionale padongelukke, te ondersoek. Die oogmerk van hierdie doel was om ’n nuwe basis te skep om die verband tussen padkenmerke en bestuurder risikofaktore voor padongelukke te beoordeel. Dit sal dien as basis vir die vergelyking van botsing risikofaktore vir toekomstige studies. Die tweede doelwit was om hoë risiko verkeersongeluk areas op die verskillende plattelandse nasionale pad- klassifikasies te identifiseer. Die derde doelwit was om die verspreiding van noodlottige en ernstige beserings-ongelukke oor die plattelandse nasionale padnetwerk te beoordeel deur die KDE- ruimtelike ontledingstegniek toe te pas. Die vierde doel was om te ondersoek of die plattelandse padontwerp eienskappe aan die padontwerp riglyne voldoen. Aanbevelings oor die geskiktheid van die ontwerpstandaarde is gebaseer op die resultate van die eerste drie en vyfde doelstellings van die studie. Die vyfde doelstelling van die studie was om nuwe voorspellingsmodelle vir padongelukke te ontwikkel; gekalibreer en spesifiek binne die konteks van die Namibiese plattelandse padomgewing. Hierdie doelstelling was ondersteun deur die ander vier doelstellings om die ruimtelike verspreiding van padongelukke, die reaksie van verspreiding van botsings op die ontwerp- voldoeningsvlakke en die sensitiwiteit van die CPMe vir veranderinge in die ontwerpkenmerke, te ondersoek. Die insigte uit die studie sal ’n langdurende en belangrike invloed op padveiligheid in Afrika suid van die Sahara (SSA) en daarbuite stel. Die studie het verskeie areas in die plattelandse padveiligheidstelsels beklemtoon wat dringend aangespreek moet word om ’n veiliger omgewing vir padverbruikers op die netwerk te bied. Namate Namibië die nuwe ‘Decade of Action’ (DoA) strategiese plan vir die tydperk 2021 tot 2030 voorberei, bied die insigte uit die studie ’n grondslag waarop plattelandse padveiligheid in die DoA aangespreek kan word, met ’n benadering wat daarop gemik is om sogenaamde latente leemtes in die komponente van ’n veilige padstelsel te verminder en uit te skakel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/123734
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