Infrastructure　systems,　such　as　bridges,　are　a　driver　for　the　economic　growth　and　sustainable　development　of　countries.　Similarly,　the　development　of　operation　and　maintenance　strategies　for　infrastructure　systems　may　aim　at　optimal　management　using　Key　Performance　Indicators　(KPIs)　such　as　reliability,　redundancy,　availability,　safety,　economy,　environmental　performance　and　resilience.　Recent　research　and　development　projects,　such　as　COST　TU1406,　highlight　that　infrastructure　managers　make　decisions　based　on　a　mix　of　qualitative　and　quantitative　data　from　various　sources　paired　with　models　of　various　levels　of　complexity　as　well　as　expert　judgement.　Similarly,　recent　state-of-the-art　academia　reports　on　a　variety　of　different　decision-making　models　applicable　to　the　optimal　management　of　infrastructure　systems　may　be　used.　Within　IABSE　Commission　5　on　Existing　Structures,　Task　Group　5.4　has　performed　a　survey　on　implemented　decision-making　models　among　23　infrastructure　managers　from　20　countries.　It　highlights　some　similarities　in　relation　to　KPIs,　condition　rating　and　limit　state　checks.　This　has　stimulated　the　standardisation　of　decision　making.　The　application　of　risk-based　methods,　performance　prediction　and　intervention　modelling　are　somewhat　more　scattered　and　may　call　for　further　research　and　development　as　well　as　training.　The　need　to　bridge　the　gap　between　implemented　decision-making　models　and　research　is　of　paramount　importance.