Case study: Replacement strategy for highway protection barriers
Background
This case study addresses the problem of determining optimal replacement interval for safety barriers for a district council. One of the main challenges is in understanding the value provided by safety barriers and determine the most appropriate replacement interval. Due to funding restraints, most of the allocated funds are directed to the upkeeping of roads, lighting and signages. Further compounding the problem is the user perception to the quality of road surface and lighting, and less focus on the need for safety barrier. Therefore, it is essential to understand the value of safety barriers and depending on the location of the barrier, the ideal replacement needs to prioritised from a value perspective.
The functionality of the safety barriers is to protect the users and other assets when accident occurs. Therefore, even a safety barrier well past it replacement period will not have any consequence unless a mishap occurs. In the following subsections, the whole-life value process applied for this particular case example is illustrated
Project objectives
The objective in this case example is to determine the optimal replacement interval for safety barriers and ensure that the value provided by safety barriers is taken into account. This optimal replacement interval should then allow the council to prioritise the replacement schedule for safety barriers depending upon the current age and the importance of the barrier. This will allow in determining the value provided by safety barriers depending on the location of safety barrier within the road network and also within the section of the road. Consequently, this will allow the comparison of various safety barriers and their difference in replacement periods. Based on this analysis, the council can devise a prioritisation strategy and schedule replacement of safety barriers.
Approach
We used the value-based approach to determine the stakeholders of the road network, and their requirements. Further the requirements of the different stakeholders were translated into a number of measurable value drivers and associated metrics. A value map was then developed - this showed how different deterioration and failure modes of the safety barriers could affect those value drivers. This value map was then translated into a mathematical optimisation model that considered a 50 year horizon to find the optimal replacement timing for a given location in the road network.
Benefits
- Cost saving by making informed choices on the timing of replacement striking the right value vs cost balance.
- Enhancing value to the organisation by providing a standard systematic approach for making asset management decisions
