Optimised Works Programs

The SMEC PMS is able to generate optimised works programs, which can be set to accomodate user-defined targets such as budget constraints, overall network condition and repair strategy.

Before the use of Pavement Management Systems, works programs were developed by simply finding the roads in the worst condition and then making a works program to address as many of these as possible within the available budget. Even today there are some asset management systems that still attempt to operate in this fashion. This is known as the ‘Worst Roads First’ strategy and it can end up costing a Council millions of dollars. To demonstrate this, the SMEC system was used to undertake an eleven year analysis on a prominent council’s road network. The analysis was done firstly using the optimisation process to maximise the condition of the network using their current annual works budget of $4.5 million. The analysis was then repeated using the same budget but enforcing the ‘Worst Roads First’ strategy.

A comparison of the results of the analysis can be seen below.

Comparing 'Worst Roads First' Strategy with the SMEC Optimised Works Program for a $4.5 Million Budget

In this figure the PCI stands for Pavement Condition Index and reflects the health of the pavement in terms of amount of surface cracking, stripping, potholing as well as rutting and pavement ride quality (roughness). A road in ‘as new’ condition would have a PCI of 10 and the more defects a pavement exhibits, the lower the PCI score. Pavements in very poor condition may have a negative PCI.

The graph demonstrates that if the works program is optimised to maximise the improvements in the network condition then the overall condition of the network can be raised from a PCI of 5.1 to 6.6 over eleven years. However if a ‘Worst Roads First’ strategy is adopted then (using the same annual budget) the overall condition of the network will fall from 5.1 to -0.1 by the end of year 11.

It should not be assumed that adopting a ‘Worst Roads First’ strategy will result in a network having fewer roads in very poor condition. The figure below shows the predicted distribution of the network condition after eleven years for each of the different strategies.

Comparing Network Condition after 11 Years

As well as being able to optimise the works program within a budget constraint, the SMEC PMS can also operate by setting a yearly ‘Target PCI’ for the network and then determining the funding required to meet this target. This facility was used to determine the budget that would be needed if the ‘Worst Roads First’ Strategy was required to match the PCI improvement achieved by the SMEC optimised works program. A comparison of the budget requirements for the two different works program strategies can be seen in the following figure.

Comparison of Budget Requirements for different Strategies to meet the same Network Condition Levels

Based on the analysis it was found that an additional $102 Million would be needed over the analysis period if the ‘Worst Roads First’ strategy was to emulate the same network improvement achieved by the SMEC Optimised works program with a $4.5 Million annual budget.