Managing SADC Roads Agencies in the New Millennium: The Role of Road Asset Management Systems
The management of the Southern African Development Community’s (SADC) road network is a complex task which is often influenced by a variety of factors – technical, financial, social and political – which all enter into the decision making process at various levels of their roads agencies. In such an environment, the determination of optimal strategies requires the use of a rational “systems” approach to road asset management. This paper outlines the road management strategy that is being pursued in a number of countries in the SADC region. It then illustrates how these systems are being used at various levels of application to achieve the desired objectives of the road agency.
LONG-TERM NETWORK PERFORMANCE - A FUNCTION OF MAINTENANCE STRATEGY
Most road agencies operate under a scenario where the maintenance need exceeds the available maintenance funds. In this environment pavement managers are forced to select maintenance and rehabilitation actions based on a defined methodology. Traditionally this was done through a ranking process where the maintenance priority was determined based on a road's importance and condition. Projects with a high priority rating were carried out first until the available funds were depleted. The more sophisticated pavement management systems utilise optimisation routines which allow for inter-project trade-offs when generating a maintenance plan. When utilising optimisation to select maintenance actions, various optimisation functions can be used. This paper shows how important the choice of maintenance selection methodology is on the long-term condition. Data from an actual road network is used and subjected to various ranking and optimisation functions. The outcome was evaluated in terms of long-term influence on network condition, overall transportation costs and asset value. It is shown that the analysis methodology selected should be compatible with the agencies' long-term maintenance objectives. (a) For the covering entry of this conference, please see IRRD abstract no. 878228.
TRAFFIC ACCIDENTS AND ROAD SURFACE SKIDDING RESISTANCE
In this research a statistical relation was sought between the skidding resistance of road surfaces and the relative road risks. In the concept of accident quotient the number of accidents that occurs on a certain section of road within a certain period of time is related to the total number of kilometers travelled on that section in the period concerned. The involvement quotient is the number of vehicles which, per million vehicle-kilometers travelled, subdivided into the categories passenger cars and goods vehicles, has been involved in an accident on a certain road surface. In order to eliminate influences other than skidding resistance, a distinction has been drawn between two types of road. Type I comprises roads with dual carriageways. Type II, which is a more discontinuous type, comprises all the other roads. The accident data (60,000 accidents) were based on records kept by the police. Vehicle-kilometers have been calculated only in so far as they were travelled during rainfall or, alternatively, when non rain was falling. The accidnets which occurred on a wet road surface, but not during rainfall, constitute a situation concerning which little can be said with certainty and have been assigned to the skidding resistance class of the wet road and to the class of dry road surfaces too. It appears from the research that each lower skidding resistance class is associated with a higher accident quotient. On the evidence of the statistical relation that has been foudn the highest possible skidding resistance is to be recommended for both types of road. /Author/