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1  OBJECTIVE AND METHODCS OF THIS THESIS

1.1  PREFACE

                                                                                        A new Road extends a man's freedom only if he travels upon it
                                                                                        Julius Nyerere

 

 

The present research for this thesis was inspired by the first steps towards an independent Namibia when, during 1979, I was asked by the Interim's Minister for Transport and Infrastructure, Mr. Werner Neef, to give a South-Africa-independent opinion about the road infrastructure in Namibia. The sources for my thesis and the course of action during the research and writing of it are determined by engineering arguments. But I have to confess that my feelings for the cause of Namibia and the Namibian people were a strong motivation to initiate and realise this work.

The numerous economic problems facing Namibia are in many aspects caused by its unique traffic situation. This traffic situation is characterised by its biased transport infrastructure towards South Africa. Nakop as current "Namibia's gateway to the outside world" is a first order handicap for the country. Transport activities could constitute a major constraint on the development of the economy of Namibia because this one-sided transport situation makes Namibia's economy highly dependent on South Africa.

Besides this, Namibia still has a structurally heterogeneous, de-integrated economy. It is characterised by the extraction and export of its mineral, agricultural and fishing resources whereas the impoverished subsistence economy of many areas serves the interests of the modern-sector-economy. Northern Namibia, in fact, is a "residual" labour reserve with little cash income or commercialised production, so that it has little effective demand for goods and services including transport facilities. This situation formed the basis for one of the characteristics of Namibian transport: its unbalance between the "modern" and the former "homeland" sector.

The objective of this thesis will be to overcome this characteristic and to develop an optimal and well balanced roads model in order to create a structurally sound and integrated economy.

1.2  THE EVALUATION OF THE CURRENT POSITION

Chapter 2 deals with the current dispensation for the Namibian roads system. The many constraints hampering a balanced roads system geared to national unity and created in the interest of all inhabitants will be critically evaluated. The quantitative analysis of the road statistics will be shown as inventory of the status-quo. From this initial position new cost and quality optimised roads models can be developed. Such development shall include factors such as the structural in-equality in the provision of infrastructure in vast areas, the creation of employment opportunities through labour-based techniques and " Namibia-Appropriate-Technologies".

1.3  THE NAMIBIAN ROADS MODEL OF THE FUTURE

Before cost and quality optimised roads models can be developed it is essential to evaluate the environmental influences on road building. Climatic and geological influences will be investigated in chapters 3 and 4. One of the characteristics of an arid country like Namibia is the difficulty to design adequate drainage structures in its roads system. High rainfall intensities, few or non-existing flood data and run-off measurements in the river systems as well as poorly known run-off characteristics of catchment areas under arid conditions leave room for research in this field. Chapter 3 also summarises the locations of all known natural road building materials in Namibia.

Chapter 4 gives a general survey of the properties of all natural road building materials, structured according to their geological occurrences and isotopic ages. Furthermore an evaluation of the experiences regarding their road building properties will be given with the concentration on key road building materials like calcretes and sand. The knowledge about the location of adequate road building materials and their properties serves as the basis to an evaluation of pavements for bitumen surfaced and unpaved roads. The thorough knowledge of the whole roads system is the essential prerequisite to develop cost and quality optimised performance models in chapters 5 to 7.

The main characteristics of such performance models will be the riding quality and deterioration mechanisms of paved (normally: bitumen surface treatments or surface dressings) and unpaved roads. Cost optimised models will be formulated on the basis of vehicle operating costs 'VOC' which, ideally, should be developed for Namibian circumstances. This will not be possible for all components of 'VOC' within the framework of this thesis. Therefore, use will be made of the experiences of the ' HDM3' World Bank Model and subsequent South African studies which will have to be verified by Namibian volumetrical fuel consumption measurements in dependence of riding quality ( roughness).

Deterioration mechanisms like loss of surfacing aggregate and bleeding as well as different forms of surface crackings of paved roads will be investigated. The objective is the development of a reseal algorithm which optimises the maintenance of such roads. The interdependence between climate, materials and traffic will be exhibited, which will result in new material specifications. After having evaluated all sections of paved roads with the aid of experimental field tests it will be possible to predict the remaining pavement lives in terms of traffic loads.

A similar research path will be followed to develop performance models for the vast network of unpaved roads. Gravel-surfaced or earth roads which represent 89,4% of the total road network have been in use much longer than bitumen-surfaced ones. Namibia's unpaved roads system is named in Africa for its excellent shape and condition but it has never been proven whether the excellent quality of these roads are effective and optimised as far as costs and quality are concerned. Basic parameters which will be investigated are dry and wet weather deteriorations like roughness, gravel losses due to traffic and natural causes and rut depths as well as stones, pot-holes and corrugations and others. These investigations will result in a new, relaxed material specification for unpaved roads in Namibia. These optimised performance models must be created for Namibian traffic patterns and materials as well as vehicle operating costs. The main objective of these investigations will be the development of a Namibian maintenance design system. Significant savings could be effected by better management of programmes for optimised grading and gravel-layer resurfacing frequencies and to establish the optimised point of upgrading earth and gravel roads to a paved standard.

Such investigations will furthermore lead to a new approach of low-volume and low-cost roads in chapter 8 which have to be developed for new design concepts at variance with conventional high standard-thinking. Design and construction standards for different classes of such roads will be compared with those proposed of the German " Federal Ministry of Economic Co-operation". The low-volume road concept will consider especially labour intensive construction methods. New appropriate, low-volume road building concepts will be investigated by experimental sections. A procedure to optimise labour intensive construction methods will have to be developed with special emphasis on the difficulties between hand and machine labour.

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