Shells　are　attractive　and　efficient　structures　that　play　a　special　role　for　engineers　and　architects.　However,　only　few　bridges　supported　by　concrete　shells　have　been　designed　and　built　after　the　Musmeci’s　bridge　in　Potenza　(Italy).　Several　numerical　form-finding　methods　have　been　implemented　in　the　last　decades　to　optimize　the　shape　of　shells.　In　the　present　paper,　a　comparison　of　the　Thrust　Network　Analysis　(TNA)　and　Particle-Spring　System　(PS)　is　made　by　searching　the　optimal　shape　of　a　concrete　shell　supporting　the　curved　cantilevered　deck　of　a　pedestrian　bridge　under　the　same　boundary　conditions.　Finite　Element　Analysis　was　performed　to　compare　the　structural　behaviour　of　the　footbridges　optimized　by　the　two　different　form-finding　techniques.　The　effectiveness　of　both　form-finding　methods　in　minimizing　unfavourable　tensile　stresses　in　concrete　shells,　thus　taking　advantage　of　mechanical　properties　of　concrete,　is　investigated.　Furthermore,　transverse　deflections　of　the　curved　cantilevered　deck　were　reduced　introducing　an　external　prestressing　system　applied　to　the　upper　flange　of　the　ring　box　girder.　Finally,　the　obtained　results　can　help　architecture　and　engineering　practitioners　to　develop　innovative　bridge　conceptual　design.　©　2021　International　Association　for　Bridge　and　Structural　Engineering　(IABSE).