## 2 Performance Indicators and Goals
### Performance Goals  
The relationship between performance goals and indicators at the level of components, systems, and networks is depicted in Figure 2.  
Various PGs have been set within the framework of a system with multiple objectives, and different bridge and network functionality factors are considered. This research finds five performance factors: Reliability, Availability, Economy, Environment, and Traffic Safety. Multi-criteria decision-making (MCDM) combines these factors with benefit/cost data, decision-maker, and stakeholder viewpoints to evaluate alternatives. However, Europe has  
Figure 1: Possible clusters of research-based performance indicators (_source:_ _COST Action TUI406_).  
Figure 2: The PIs and PGs enable component, system, and network assessments (_source:_ _COST Action TUI406_).  
a significant variance regarding quantifying performance indicators and defining objectives. Furthermore, when considering the Reliability-level at the aged state, different maintenance options should be considered, especially for the bridges below the threshold. The following three scenarios are typically considered: \"do nothing\", \"minor to major repair\", and \"reconstruction\". Each option, if chosen, will have both direct and indirect impacts. The direct impact, such as direct costs related to maintenance activities, is often assigned as the owner's cost and therefore represents the economic aspect of the bridge projects. On the other hands, indirect impacts, such as environmental impacts or traffic delay, are quantified in two stages: during regular operation or during maintenance interventions. The overview of suggest KPIs for each performance aspect is given in the Figure 3:  
Figure 4 depicts a procedure for assessing performance objectives and transitioning to the network level. Since the focus on the effective execution of network-level performance increases, it extends the demand for information within the interactions between social goals and roadway networks. Leveraging asset management should improve infrastructure requirements for performance integration. When doing so, bridge and roadway administrators face several challenges, such as quantifying performance objectives and indicators, transforming from the level of the network to the level of the object and vice versa, and establishing comprehensive PIs.  
Typically, network and even social goals are defined broadly. In addition, smaller-scale PIs and higher-level objectives frequently lack exclusivity. Furthermore, in many nations, the condition evaluation of specific structures and components is continuously the main focus of bridge management. This research includes capturing performance objectives, from strategic decisions at the highest level to system-specific requirements. It likewise attempted to clarify how different performance aspects, including traffic safety, availability, economy, and environmental and social impacts, can be quantified and incorporated into the multiple-purpose bridge performance objectives evaluation. The standardization of evaluation procedures, accumulation of performance indicators, measurement of KPIs, and the establishment of field-applicable maintenance tools for optimization should be paid more attention.  
Figure 3: Multiple PGs link to PIs (_source: COST Action TUI406_).  
Figure 4: Overview of the procedure for assessing performance objectives and transitioning to the network level (_source:_ COST _Action TUI406_).