Challenge

Structures were managed based on a worst-first condition approach, with no consideration of the consequences of not maintaining other structures in need. The current process did not incorporate a lifecycle analysis.

The consultant, Zutari, set out to implement a risk-based lifecycle analysis for the municipality’s road structures network in dTIMS. This approach considers environmental, social, and economic impacts, and allows for a better balance in risk, cost, and asset performance of different roadside structures over time, considering different asset lifecycle stages.

The risk of a structure deteriorating to a very poor condition was considered, and Markov Chain deterioration models were used to define the transition of a structure from its current condition to a worse condition.

Solution

Through the dTIMS analysis, the consultant was able to view the predicted condition and risk over time for the entire structures network, as well as for individual structure types. The client was also able to see the impact of various funding levels on the condition and risk. Through the risk reports, it was possible to identify that structures such as retaining walls for example were at a higher risk than lesser culverts.

This new risk-based approach was compared with the existing worst-first approach. It revealed that for the municipality’s bridges, the risk-based approach results in a reduction of risk each year with a max of Rand55 billion (24%) lower risk in the final year.

Results

Under budget constraints, risk-based approach yields more cost-effective results than “worst condition first” method.