With the recent development High Performance Steels (HPS) for bridge applications, appropriate matching weld consumables are only now becoming available. Research has shown that undermatched welds in HPS steels made with readily available but lower strength weld metals can provide weldment strength and ductility equivalent to overmatched joints. These are called “optimized welds”. The research reported defined several of the parameters that control optimized weld joints in HPS 70W and 100W steels. The parameters included the degree of weld undermatching and width-to-thickness ratio of the plate. It was shown that, for 38 mm thick plates, the width to thickness ratio of the weldment nust be greater than 7 and the level of strength undermatch must be no greater than 20% for HPS 70W and no greater that 10% for HPS 100W for successful weldment optimization.