SADC Roads Subsector Harmonization Studies
- Référence: P-Z1-DB0-049
- Date d'évaluation: 15/03/2008
- Présentation au conseil: 15/03/2008
- Statut: PipelinePIPE
- Agence d'implémentation: SOUTHERN AFRIC. TRANSP & COMMUNICAT. COMMISSION
- Emplacement: SADC COMMUNITY
The studies are designed for the preparation of Deep in-Situ recycling Design Guidelines and Harmonized Material Testing Manuals for the region by adopting best practice.
Guidelines for the Use of In-situ Recycling for the Upgrading and Rehabilitation of Roads in SADC;
Deep in situ recycling involves the re-use of the existing surfacing seals and pavement layers through milling to specific grading using purpose made machinery. Addition of stabilisers is commonly used to improve the structural capacity of the material. Where the lower layers still have adequate strength the milling of the material and addition of the stabilisers can be carried out in one operation followed by placing and rolling the milled material. Where the lower layers require strengthening the material can be put to windrow and re-worked afterwards.
Deep in situ recycling has over the last decade become the favourable method of pavement rehabilitation due to its advantage of reducing the exploitation of new sources of road building materials. Over exploitation of resources for road construction has resulted in the scarcity of good quality road building materials and therefore recycling contributes to the conservation of the environment in addition to limiting the negative affects of land take required for borrow-pits. However the non-homogenous nature of the materials requires knowledge and understanding of the processes required during pavement evaluation, design and construction. The project through a desk study will collate research done internationally and the region, make reference to the existing guidelines and specifications for in-situ recycling and use data from case studies to prepare a document for the region.
Harmonized Materials Laboratory and Field Testing Manuals for the SADC Region;
Road construction costs largely depend on the quality, quantity and location of the road building materials and therefore identification requires high standard of testing methods to ensure cost effectiveness. Significant cost savings are achieved when good quality material prospecting and testing is carried out at detail design stage.
The varied methods and procedures used for laboratory and field testing in the region results in different standards of the finished product and reflect the quality of that section of road on the RTRN. Materials' testing is normally prescribed in various manuals, of which the British Standards (BS), American Society for Testing and Materials (ASTM) and the South African Technical Methods for Highways (TMH) are in common use in the region. The manuals differ in many respects with regard to actual procedures and method of testing. Material testing assesses the properties of road construction materials as an indicator of their likely performance under traffic. With the differences in the test procedures followed by most of SADC countries there is no unified regional practice. To resolve this problem a project to Harmonize Materials Laboratory and Field Testing Manuals is necessary. The preparation of appropriate testing manuals will eliminate the use of specifications developed under different climatic conditions by adopting Manuals that suit the southern African conditions and traffic characteristics. This study will review the different manuals used in the region and elsewhere and adopt a harmonized manual suited for the region.
Dissemination of Outputs
The Guidelines and Manuals are intended to harmonize roads sub-sector methods and practices in the SADC Region and the study outputs will require dissemination to the stakeholder agencies in the region through workshops. The exercise will also include the translation of the Guidelines and Manuals into the other two official languages of the region, namely, Portuguese and French. ASANRA in collaboration with the SADC Secretariat are to organize the workshops and facilitate attendance by member countries, arrange for the required conference facilities for the consultants to present the guidelines and manuals.
The specific objective of the studies is to provide roads authorities in the SADC region with best practice by developing guidelines for use in in-situ recycling for upgrading and rehabilitation of roads and harmonized manuals for laboratory and field-testing of materials.
The SADC Protocol commits member states to facilitate the establishment of transport systems that provide efficient, cost-effective and fully integrated infrastructure and operations that best meet the needs of customers and promote economic and social development while being environmentally and economically sustainable. Specifically the region is to promote provision of economically viable integrated transport services characterized by high performance standards and consistent leve ls of efficiency and reliability. The roads sub-sector has made significant progress towards this objective through extensive reforms in member states that have created enabling environments for cost-effective and efficient management of the road networks.
The roads sub-sector in the SADC Region is central to the enhancement of economic activities within states and across borders and plays an important role in attracting investment. A core road network referred to as the Regional Trunk Road Network (RTRN) has therefore been identified to serve as the basis of a coordinated plan and implementation of maintenance and development of road projects of regional and international importance within the framework of national programs. The RTRN comprises some 50,000 km of strategic intra-regional routes that provide access to major centres of population and economic activity and link major ports and harbours to landlocked countries.
Within the RTRN, regional transport corridors have been identified in which investment has been directed to facilitate easy access to the sea by the land-locked countries and at the same time stimulate economic activity along the routes that the corridors traverse. Portions of the corridors are part of the Trans-Africa Highways, namely the Beira-Lobito Corridor and the Cape Town to Cairo and the Cape Town to Tripoli Highways. With the exception of the North-South Corridor running from Durban through Botswana to Lusaka in Zambia the other corridors run in an east-westerly direction.
Because of their importance and the role they are intended to play in socio-economic integration of the region through free movement of goods and people, across borders, priority has been placed on harmonization of standards along the corridors to ensure uniformity. Prior to its restructuring in 2000, the task of harmonization was entrusted to the Technical Unit of the Southern African Transport and Communications Commission (SATCC-TU) which became the custodian of regional standards on transport. Since then the roads sub-sector has adopted common standards on geometric design, bridge and culvert design, road signs and markings, standard specifications for bridge and road works, driver training and testing among others which are in use today. After restructuring the custodianship of the standards was devolved to the Association of Southern African Roads Authorities (ASANRA), the executing agency proposed for the studies herein.
The Bank and NEPAD's strategy for the Regional Economic Communities (RECs) in infrastructure is to support interventions that create an enabling environment for delivery of services. The studies referred to herein will promote dissemination of best practice in infrastructure development and operations through harmonized guidelines and manuals for the roads sub-sector.
Most of the RTRN was constructed during the post independence era in the 1960s and 70s with the rapid expansion outstripping the maintenance budgets and institutional capacities. Increases in traffic volumes coupled with significant overloading of heavy goods vehicles have resulted in exceeding the structural capacity of the pavements followed by rapid deterioration. The age of the network coupled with its misuse has necessitated innovative ways of rehabilitation to ensure re-use of the existing materials for the pavements through recycling and stabilization. There is recognition in the region that uniformity of the network requires harmonization of standards.
The cost of road construction largely depends on the location and distance of the source of materials for the pavement layers. Recycling eliminates borrow materials and therefore the cost of haulage. Good quality material testing minimizes haulage costs by locating materials at optimum distances. The economic justification resulting from the guidelines and manuals relate to the cost saving that will accrue to the member states with their use for rehabilitation and upgrading of roads on top of the environmental and social benefits.
KIGGUNDU Lawrence - OITC2