Once the design life of a haul road expires, or traffic volume and/or truck types change, a haul road rehabilitation or upgrade is indicated, to ensure the road continues to perform it’s design function –  safe, vehicle friendly and economic.

Re-design or rehabilitation will depend to a large extent on the existing subgrade, design layerworks and wearing course and the extent to which these meet the newly defined road-users needs, in terms of a category I, II or II road design.

For further details, see the book:

Mining Haul Roads: Theory and Practice
1st Edition
Roger Thompson, Rodrigo Peroni, Alex T. Visser

CRC Press
Published December 11, 2018
Reference – 294 Pages
ISBN 9781138589629
CAT# K386669

Further technical background is available here.