The aim of this document is to provide guidance to planners, designers and practitioners of rural roads in developing and transition counties. It is based on proven techniques and experience and should be the basis of introduction of low cost but durable construction practices in environments experiencing severe resource restrictions. It is intended that rural road practitioners and professionals will be able to utilise and adapt the knowledge in this document to introduce more appropriate, affordable and sustainable techniques, standards and specifications into everyday practice, academic curricula and training, and contribute to rural poverty reduction. The Guideline consists of 4 Volumes: * Volume 1 - Planning and Preliminary Design; * Volume 2 - Detailed Design, Construction and Maintenance; * Volume 3 - Bills of Quantities and reduced drawings; * Volume 4 - A3 size drawings. This is the third volume of the guideline covering the design, construction and maintenance of road structures on low volume roads. A broad introduction to the guideline is provided in Volume 1. The guideline covers a wide range of drainage structures from drifts to small bridges (Chapter 4 in the design manual, Volume 1, describes the characteristics of these structures). These structures vary in complexity and are ranked in order of increasing complexity as follows: • Drifts; • Simple culverts; • Vented fords; • Large bore culverts; • Small bridges. This volume of the guideline contains standard designs and bills of quantities for low cost structures. It is hoped that by standardisation of these designs, which have been checked technically: • economies of scale will lead to an improvement in cost and quality; • speed of construction will be increased as labourers, supervisors and engineers will be more familiar with the design; • approval procedures will be simplified. The guideline has been written as a design guide, to complement design codes and standards from the relevant Ministry or Roads Authority. However, experience has shown that in many areas national design standards are not applicable to the small cost structures on Low Volume Rural Roads (LVRR) covered by this guideline. It is therefore envisaged that this document will be recognised by road authorities as a useful tool and that, by following the advice and information contained in the guide, engineers and technicians will be able to design, construct and maintain acceptable and durable structures. Steps in the design process for road drainage structures are often missed or neglected. Volumes 1 and 2 therefore explain the steps that should be carried out and the reasons for undertaking them. They also explain the type and detail of information required and how it should be used to undertake a design. The designs contained in this volume are standard designs and may therefore not be fully applicable for all structures. Small modifications to the drawings may be required for individual circumstances. Before using these designs, engineers and technicians should consult Volume 1 and 2, to ensure that the drawings are suitable for specific water crossing locations. Volume 4 contains the drawings at full scale ‘A3’ format. The drawings in this Volume 3 are reduced in size and are for reference only and cannot be ‘scaled’. (Author/publisher)
Samenvatting