THE INVESTIGATION AND DESIGN OF THE ACCESS ROADS FOR THE LESOTHO HIGHLANDS PROJECT

This article described an investigation for and design of the access roads for the 1St phase of the lesotho highlands project. Extensive geotechnical investigations were carried out. The mountainous terrain of the region required analysis of the stability of cuts and fills, and the natural slopes. Remedial measures were proposed for the unstable slopes. Road alignments were adopted to ensure that the road surface was positioned cut on natural material on the steep sided slopes. A carriageway width of 7 metres with 0.5 metre shoulders and a 0.8 metre unsurfaced area was adopted for the northern access road. The proposal for the southern access road was for a 6 metre formation width with an all gravel surface and widening at tight curves. Computerised design methods were utilized to generate the possible road layouts. The structure of the bridges at malibo-matso, and katse were briefly given. The following environmental influences on road pavement performance were considered important for the pavement design: (1) freezing and thawing; (2) weathering; (3) the availability of suitable materials; (4) and the presence of water. Weathering tests have shown that weathered basalt, the most common material, could not withstand cyclic freezing and thawing and was not therefore suitable for use as a basecourse material. Adequate drainage measures were therefore essential and a porous structure was proposed, covered by a relatively impervious asphalt seal, which also had some structural strength. (TRRL)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00097845
• Corporate Authors:

  South African Institution of Civil Engineers

  9 St David's Place
  Parktown,   South Africa 

  SOUTH AFRICAN INSTITUTE OF CIVIL ENGINEERS

  9 ST DAVIDS PLACE
  Parktown,   South Africa 
• Authors:
  • -
• Publication Date: 1988-11

Language

• Afrikaans

Media Info

• Pagination: p. 509,511
• Serial:
  • CIVIL ENGINEER IN SOUTH AFRICA
  • Volume: 30
  • Issue Number: 11
  • Publisher: South African Institution of Civil Engineers
  • ISSN: 0009-7845

Subject/Index Terms

• TRT Terms: Basalt; Base course (Pavements); Bitumen; Bridges; Design; Drainage; Flexible pavements; Freeze thaw durability; Highway design; Layout; Pavement design; Surveying; Weather resistance; Weathering
• Uncontrolled Terms: Site investigation
• Geographic Terms: South Africa
• Subject Areas: Bridges and other structures; Design; Highways; Hydraulics and Hydrology; Pavements;

Filing Info

• Accession Number: 00499157
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Files: ITRD, TRIS, ATRI
• Created Date: Sep 30 1990 12:00AM