Influence of the Quality of Structural Engineering Design on Cost Certainty of High-rise Building Projects in Nairobi City County, Kenya

Abstract

Clients are increasingly demanding a high degree of cost certainty from their project design teams to ensure that their building projects are completed within the budgeted resources. However this objective has been negated by various challenges that unfortunately cause budget overruns. Errors in design and documentation has been identified by previous studies as one of the major contributing factors to the problem of budget overruns and hence low cost certainty. The quality of structural engineering design in terms of accuracy, completeness, integration and build-ability in the multidisciplinary nature of projects plays a central role of defining and specifying the building blocks that account for a large proportion of the building cost. This study sought to investigate factors that bear on the quality of structural engineering design and subsequently influence the cost certainty of high-rise building projects in Nairobi County. A quantitative sample survey research methodology was used to assess the influence of structural engineering design coordination, level of engineering experience, the type of design software and amount of design fees on the quality of structural engineering design and subsequently the cost certainty of high-rise building projects. Respondents were consulting civil engineers drawn from the Engineers Board of Kenya’s register using probability interval sampling technique. From this register 150 consulting engineers domiciled within Nairobi County were randomly selected and contacted using a web based structured questionnaire. Analysis of variance and Chi-square tests showed that design coordination, level of engineering experience, the type of design software and amount of design fees are correlated to cost certainty. Design coordination significantly helps to narrow gaps, uncertainties and risks as well enhance better understanding of the project scope. The level of experience is critical for problem solving, effective use of design software, quality control of design and documentation and integration. The amount of design fees directly influences the capacity of engineering firms to employ competent engineers. The design software influences accuracy and completeness of design output and consequently the accuracy of pre-tender cost estimates used for procurement. These four variable were found to be statistically significant and therefore the alternative hypotheses H1: The quality of structural engineering design influences cost certainty of high-rise building projects was supported.