Chrispin Pettang

Estimating building materials cost in urban housing construction projects, based on matrix calculation: the case of Cameroon

Abstract This paper presents a new approach in estimating the cost of building materials for the housing industry. It aims at assisting the various actors involved (client, builders, property developers, sub-contractors and jobbers, municipal officials in charge of issuance of building permits, administrative officials in charge of definition and orientation of housing policy, etc.) in mastering the use and cost of building materials as well as to evaluate the cost of projects. In contrast to the classical method consisting in estimating costs on the basis of built surface area per square meter of materials, workmanship, and management, this paper is based on splitting up the total cost of the project into cost of materials, cost of man power, and cost of management (running costs). Furthermore, it shows the manner in which any user may proceed to estimate the cost of the materials: he shall, first of all, set up a materials quantity matrix, and then set up a unit cost matrix corresponding to the materials. The paper finally gives a comparative study, which can aid in decision making in view of solving the problem of urban housing shortage.

A NEW APPROACH FOR CONSTRUCTION PLANNING IN THE DEVELOPING COUNTRIES: THE SUB-STRUCTURE CHAINING DIAGRAM (SSCD)

In the Developing Countries (DC), it is often very difficult to gather sufficient financial resources to lead a project of construction until term. It is thus advisable to adopt a methodology of suitable planning in the construction industry. This paper is interested in the manner of programming the rare resources to achieve the goal of construction. We propose for that the Sub-Structure Chaining Diagram (SSCD), which is an approach consisting in breaking up the budget into sub-budgets, each one corresponding to a precise sub-structure. The programming of the sequences of construction will be dictated at the same time by technical constraints and the availability of resources.

Pour un système interactif d'aide à la décision pour la résorption de l'habitat spontané en milieu urbain

ABSTRACT The developping countries are facing many urban problems caracterized by the proliferation of spontaneous habitat in quarters. This paper describes an approach of intervention in urban sector in order to improve the knowledge and the management of characteristics parameters (site, land, building, road, network, equipement) of a quarter. According to the complexity of decision in town management and the diversity of datas to manage, we propose a computer—based solution. It frees the different actors of urban management from the fastidious work of data collection, data organization and manipulation before any decision making. In this paper, a first step is realised concerning the data storage and the judicious presentation of statistical datas to the decsion makers. The system to implement allows through its flexibility and its interactivity to help them in the decision making process. This approach is closed to a real DSS (decision support system): the datas are formated in a way that can improve ...

A new and rational approach to modelling and designing potable water and electricity supply systems in African cities

Abstract The problems of supplying African cities with potable water and electricity are characterised by uneven capacities of the networks, inefficiencies of supply, low subscription rates and low rates of return. This paper proposes ways of improving access rates of city dwellers to potable water and electricity without reducing the technical and commercial efficiencies of network managers. The main innovation consists in associating urban households to technical decisions aimed at expanding the network programming, by collecting pertinent variables such as consumption levels and contributive capacities of households, thus highlighting the need to draw up flexible and appropriate standards. These are formulated in terms of consumption and failure rates, and in terms of the thresholds used to evaluate risk and availability. The graphical method of risk evaluation developed here may be a useful tool for decision making on matters related to network extension. The model developed was tested in three Cameroonian towns. A comparison of this method with the classical approach shows that the method improves availability by as much as 40% in the three towns studied, while also improving significantly the technical and commercial efficiencies.

A NEW PROPOSITION FOR THE CURBING OF SPONTANEOUS HOUSING IN URBAN AREA IN CAMEROON

Abstract In Cameroon, quarters with spontaneous housing occupy more than 60% of urban areas and concern about 75% of town dwellers. These quarters have a negative impact on the urban environment but are the focus of an intense communal life. These highly dense zones of insalubrious housing constitute the main emanation of urban disasters, very high in Cameroonian towns: fires, floods, air or underground water pollution, landslides, torrents which take away children. The solutions up to now have been based on typical models of restructuring and settlement which have shown their limits. Our new proposal takes advantage of a better knowledge of the site and its two components; it may be summarised as: (i) restructuring and valorisation of the informal sector of housing production; and (ii) distribution and sharing of the resorption responsibilities between the partners, i.e. state, NGOs and the users , taking the efficiency into account. These actions must be clear, simultaneous and must integrate simple solutions or even selective support for each of the partners.

Amélioration du processus de gestion du permis de construire dans les villes des pays en développement. Le Cas de Yaoundé (Cameroun).

The habitat in the cities of developing countries is facing serious dysfunctions. The lack of respect of the regulation as regards of town planning, often involves the anarchistic occupation of the urban space in particular in the areas of spontaneous habitat. In this article, we propose a decision aid system, which could contribute to the improvement of the process of regularization of the permit building. The main point of our studies is laid on the interactions with the existing tools of storage and treatment. Three types of interactions: 1) the functionalities of the data base management system; 2) the queries from the data base; 3) the presentation of the results of the instruction. In view of the processes and the tools proposed, the town planners and managers could start a reorganisation of the spontaneous habitat while increasing the royalties.

Un SIAD pour la régularisation foncière dans les tissus d'habitat spontanés au Cameroun

ABSTRACT The phenomenous of spontaneous habitat is the crucial problem of the urban growth in Cameroon. The recent analysis show that it can be caracterized throught six parameters: site, land, building, network, road, equipment. The land is the most important of those parameters because the soil is the support of any urban installation. On the other hand the local knowledge, the past or current compromises, and the set of laws are critical for the control of the landed management. Those elements produce voluminous datas to manipulate. This paper describes a DSS for the landed regularization in quarters of spontaneous habitat. We used an object oriented approach for the analysis of the problem and the design, a procedural language for the implemention and a Geographic Information System (GIS) for the interface of the system

Building Construction Practices in Developing Countries

In this chapter, an overview of construction practices in developing countries will be examined. Although, practices from developing countries will be covered, the focus will be on Cameroon. The chapter commences with an overall background where challenges facing construction practices are discussed. Then an overview of the geography of Cameroon is presented. The two main sectors, the formal and informal where construction flourishes are discussed. The major risk factors and challenges related to materials, man-power and site management are also examined. Towards the end of the chapter the growing recognition of the informal sector is acknowledged as the future trends in most developing countries.

Analysis of the Fire Risk as a Tool of Decision-Making Aid for Problems of Planning in the City of Yaounde

The life space of populations is materialized by the habitat. This habitat spreads with the population increase. In the urban area, the transformation of the habitat is sometimes accompanied by problems like, segregation, risks.., rais- ing the problem of the zone planning. The case of fire risk in the city of Yaounde is mentioned here and calls for an analy- sis, in a context that clarifies on decision making for problems of zone planning. The strategy of approach here is to determine steps of phenomenon analysis, to describe the fire risk in its evolution while unveiling the derived information, which can characterize the urban area; an application is made to the city of Yaounde. At the end of this survey, the elements of definition and characterisation of the fire risk in urban area follow by character- istics of the city zones of Yaounde, taking account fire risk and measures to remedy them have been done. The urban area ensures to populations several functions including sanitary, social, administrative, etc.. Difficulties of management increase with the expansion of the city. Those of developing countries are the main concerned. These man- agement difficulties become more pronounced with the ap- pearance of several problems (poverty, segregation, risk, etc.). Thinking about solutions, it would firstly be necessary, to provide knowledge concerning them. It is the case of fire risks in the city of Yaounde of which we propose to study the complexity of existence in order to provide information of decision-making for problems of urban planning. There is a relationship between fire risk and the elements of habitat; what strategy of risk analysis is necessary so as, to provide information of solution to the problem of zone plan- ning? For that, we have counted all elements of existence of fire risk in their space while following its setting up since the appearance until the occurrence of the fire catastrophe (1). We also propose to the relations and properties between these elements. This numbering leads to the determination of natures, and possible types of entities. This description of existence of fire risk in its environment permits to discover factors of risk (2), including mainly elements of habitat, and to characterize zones and constructions concerned. Looking forward to eliminate these factors, we have proposed solu- tions to the planning of zones.