An appraisal of the Ghana Highway Authority road design guide

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The Ghana Highway Authority Road Design Guide (GHA RDG) is over two decades old since it was published as a draft document in 1991. It was expected to be periodically updated and revised based on observations, comments, suggestions and criticisms from stakeholders as they utilised it. As of October 2015 however, no update or revision has been carried out. Increasingly, designers undertaking projects for the Ministry of Roads and Highways, in-house design engineers in the Ghana Highway Authority, consultants and other expatriate designers of projects in Ghana are resorting to the use of several other manuals as references for highway designs. As a result of this highway design in Ghana has become more laborious; it is difficult to ensure uniformity of design, consistency of designs across the trunk road network and also vetting of consultants’ design presentations has become very laborious. The aim of this study was to make an appraisal with a view to modifying the Guide. The specific objectives of this study were first to critically assess the suitability of the GHA RDG and its contents regarding capacity, safety and economy for the geometric design of elements for modern trunk and urban roads. Secondly, the study was also to make an assessment of commonly used sources and standards for road element design in Ghana over the last ten years and thirdly to provide a theoretical basis for inclusion or otherwise in the GHA RDG. In order to achieve the objectives of the study views of experienced highway designers regarding the suitability of the GHA RDG for current highway design were sought through the administration of questionnaire. The GHA RDG was also compared with some current highway design manuals in Africa and the United States of America for suitability. The results indicate that the GHA RDG does not meet several of the requirements for current highway design in Ghana. Because of its deficiencies, highway designers in Ghana are resorting to other standards including the Green Book, AASHTO’s A Policy on Geometric Design of Highways and Streets, and the Ugandan Geometric Design Manual, to mention a few, as references for geometric design. It is therefore necessary to revise several aspects of the Guide to ensure its suitability for modern highway designs in Ghana. Also, many areas would require revision and the inclusion of several topics which are not covered. A recommended table of contents for a revised GHA Road Design Guide has been proposed.
A thesis submitted to the Department of Civil Engineering, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of Master of Science,