Ferguson Paulse, Roads Authority (Namibia)
The purpose of this paper is to illustrate the process of selecting and prioritizing surface treatments such as reseal, in Namibia. Roads Authority of Namibia has an IRMS (Integrated Road Management System) of which the PMS (Pavement Management System) is a subsystem. PMS is a software tool that assists decision makers in identifying and prioritizing potential projects and optimum maintenance strategies. Once potential projects for reseal are identified by the system, the system generates a reseal priority list of projects at network level, which is then circulated to Regional Engineers, PMS Manager and appointed Consulting Engineers (responsible for reseal projects) for scrutiny. The team then evaluates the PMS recommended action, priority and confirms the project start and end. Results of these panel inspections form the basis of a three-year reseal work program.
The data that feed the PMS is collected through standardised Visual Assessments, conducted with a Cloud-based Tablet application; mechanical surveillance measurements that collect road roughness and rut depth using a laser road surface profiler and; Pavement strength measurements using a Falling Weight Deflectometer. The PMS module uses the pavement structural condition, pavement performance and prediction method through historical deterioration to determine both the Surfacing and Structural remaining life.
The reseal type selection process uses the type of distress, their degrees and extents, traffic volume and turning actions, the coarseness or variation of the existing macro texture and road importance, using decision trees. The cost-effectiveness of different reseal types are then evaluated using costs and benefits through an “area under the curve” approach.
During the panel inspections, Regional Engineers share their experience of previous work under various condition in their areas and in some cases, question the selection of correct pre-treatment and reseal types. These comments are then fed back into the PMS and used to improve the PMS models through its adjustable rule sets.
Panel inspections, facilitated by experienced practitioners, are also used for capacity building, allowing young engineers to carry out ball penetration and sand patch testing with explanation of how all gathered information is used to select and prioritise appropriate actions.