Data analysis in this study was carried out in several distinct but linked phases, with previous phases progressively leading to latter phases, as a strategy of explanation building advocated by Yin (2015), to ensure internal validity in explanatory case studies. The multiple analytical techniques deployed for this purpose are briefly outlined, although further detailed breakdown of the approach deployed at each phase is provided in the subsequent chapters of this thesis.
4.16.1 Exploratory Geo- Statistical Analysis
The researcher began the analysis from the exploratory phase of the study, by developing a geotechnical classification of subsoils in the Niger Delta, as a form of quasi experimentation. Broad conceptual geomorphic categorisations of Niger Delta soils, as used in engineering geologic application, were synthesized from the local literature, to highlight its geologic heterogeneity. Based on the synthesized geotechnical classifications, cost overrun data for the geologic zones identified as having similar subsoil characteristics, are analysed using a quasi- experimental design approach, for significant differences in the level of project cost overrun incurred on highway projects. Analysis of Variance of cost overruns incurred on a sample of sixty- one completed highway projects, spatially distributed amongst the synthesised zones, was thus carried out to infer whether the differences in the geology of project locations has any bearing on the level of cost overruns recorded in the highway projects, executed by the 3 highway agencies operating in the region.
Further to this, the various engineering parameters, which represent the suitability of sub-grade soils in the Niger Delta, as bearing media in highway construction, are inferred as the factors which are latent in the geologic setting. Geotechnical data on sub-grade soils referred to as ‘Index properties’, which provide quantitative parameters that reflect the properties of soils, as applicable to highway designs, are used to extrapolate the basic engineering suitability of the sub-grade soils at the spatially dispersed project locations in the Niger Delta region. This explorative geotechnical phase was useful to show the inherent capacity of the geologic configuration of the Niger Delta terrain, to compound the cost overrun propensity of highway projects. This served as a backdrop to understanding the level of geotechnical risk the terrain possesses, and which should ideally be catered for by adequate geotechnical practices.
On this basis, a descriptive spatial geotechnical analysis of Niger Delta soils was carried out, using standard engineering classification of sub-grade soil types, and their financial implications as bearing media in highway construction analysed. A set of hypotheses to statistically test for association between these geotechnical index variables, relating to the stability and expansivity of soils, and cost overruns are tested using correlation analysis, which subsequently forms an integral part of the stepwise regression modelling used latter in explanation building. This constituted the preliminary geospatial exploratory phase, upon which the descriptive qualitative phase, targeted at eliciting information on the prevailing geotechnical practices of the highway agencies, was built.
4.16.2 Descriptive Qualitative Analysis (Deductive)
Further to the initial exploratory analysis, the researcher identified geotechnical best practices from the literature, to account for the deduced disparity in cost overruns levels, revealed from the geo-spatially distributed pattern of the cost overrun data. A conceptual framework of geotechnical pathogens, identified from the literature on geotechnical best practices, was developed and served as a basis for drafting the interview template. The interviews were used to elicit information on the prevailing level of adherence to geotechnical best practice by the highway agencies, during the design and estimate phases of project development. The elicited data was thematically analysed, relative to the standards of geotechnical best practices. This were inferred as the primary triggers to cost overruns, as they exhibited a pathogenic latent effect, which exacerbated the inherent propensity of the wetland terrain of the Niger Delta. The analysis was carried out using the NVIVO-10, qualitative data analysis software, after transcribing the interview notes.
4.16.3 Descriptive Qualitative Analysis (Inductive)
Other non-geotechnical social constructs which were unanticipated, however emerged from the interview data, and were reflexively infused into the qualitative analysis. The inductive interview analysis was carried as a second stage of qualitative data analysis, whereby the researcher re- read the interview transcripts and matched patterns repeated occurring across the data. The analysis in this regard was thus carried out without a prior literature base similar to grounded theorising. A multiplicity of social constructs was inductively inferred as the barriers to geotechnical best practice, and by extension contextual drivers to cost overruns.
This phase was further structured to build on findings emanating from the results of the previous sets of analysis. This entailed the triangulation of output from: the geospatial factors deduced from the quantitative archival project data on cost overrun and subsoils variables; together with the qualitative findings on the geotechnical themes inferred from the interview analysis, using regression modelling. A multiple log regression model was generated, by a step-wise introduction of categorical dummy variables to represent the assessed levels of geotechnical practice, which varied depending on the class of project and the executing highway agency. This was further juxtaposed on ground conditions at the respective projects locations, as indicated by the quantitative spatial geotechnical data on sub-grade soils.
Regression modelling was thus used to infer causality, explicitly quantifying the proportion of variance in the cost overrun data, accounted for by the inherent geotechnical properties of subsoil at project locations, and the variance induced due to lack of geotechnical best practice. Some of the variation in the recoded cost overruns however remained unexplained. The unexplained variation in the regression analysis, was attributed to the emergent social constructs. This served to tie up the multiple stands of analysis, and establish the chain of evidence pointing to how the levels of geotechnical input account for cost overruns in estimates. The triangulated findings were thus presented as a quantitative model, which explicitly showed how poor geotechnical practices and the geology of project location in the Niger Delta, accounted for a greater percentage of the variance in cost overruns recorded on highway projects.
Cognitive Mapping was subsequently used to map out the interplay between the geotechnical pathogens and emergent themes, which are represented as the barriers to geotechnical input, in accounting for the unusually high levels of recorded cost overruns in the Niger Delta. The emergent barriers to geotechnical are however relatively weighted and ranked using content analysis, based on the number of coding references made to each emergent node. The result of the cognitive mapping is a visual projection of the intricate complexity of the interplay, and the counter factual phase dependent relationship between the core geotechnical factors and the corresponding emergent barriers, with nodes relatively sized to reflect their ranking.
4.17 Chapter Summary
This chapter has articulated all the elements of the research methodology of this study, from the higher order philosophical underpinnings of the study, down to the more practical issues of data
collection and analysis. Critical arguments and justification of the choices made at each level of the hierarchy of the research elements has also been provided. The case study approach has been adopted as the research strategy in this study. In more practical terms, broken down into the specific processes and phases as applied to this study, the research methodology translates into the following case study research design represented as a flow chart in Figure 4.11.
Figure 4.11: Overall Case Study Research Design
Figure 4.11 thus shows an outline of the various practical phases of the case study, and the systematic stages used in developing an explanatory model of latent geotechnical pathogens and contextual drivers to highway project cost overruns, predicated on the geologic context of the study area. The subsequent chapter is a detailed geo-spatial quantitative analysis of the geologic configuration of the Niger Delta region of Nigeria, as an exploratory phase of the study, highlighting the magnitude of ground induced financial risk to highway project delivery.
THEORETICAL FRAMEWORK Delays and Abandonment in the Niger Delta Cost Overrun Explanations Geotechnical Best Practice TESTED IN EMBEDDED CASE STUDY (A critical Realist Orientation) DATA Interviews (16Nr) 4Nr Civil Engineers 6Nr Qty Surveyors 3 Nr Consultants 3 Nr Contractors Spatially Distributed Regional Geotechnical Index Data Cost Overrun Data 148Nr Projects 61Nr completed DESCRIPTIVE VIEW OF GEOTECHNICAL PRACTICE Mapped Against COGNITIVE MAP OF EMERGENT CONTEXTUAL BARRIERS EXPLANATORY REGRESSION MODEL OF LATENT COST DRIVERS CONCLUSION AND RECOMMENDATIONS Further Research on a Risk Based Transformation Framework
Overall Research Design
CHAPTER 5
Exploratory Geo-Statistical Analysis of Latent Geologic Cost Overrun
Drivers
5.0 Introduction
This chapter of the research is focused on exploring the geologic peculiarities of the Niger Delta region (Unit of Analysis 1), which has made it a significant geographic area of scholarly interest in this research. This chapter describes the difficult terrain of the Niger Delta region, in relation to the poor engineering index properties of subsoils, and statistically explores this geotechnical undertone as a potential trigger which creates a propensity for cost overruns in highway projects. The heterogeneous geologic configuration of the area, in terms of its geomorphology is thus descriptively analysed based on available local literature, supplemented by the researcher’s geotechnical field work data. Exploratory statistical tests of significant difference and correlation analysis, are further used to analyse recorded cost overrun data for 61 completed highway projects. The ultimate goal of the geo-statistical analysis was to establish spatial cause and effect relationships, between the heterogeneous geologic setting of the Niger Delta and cost overrun trends evident in highway projects.