Many New Zealand bridge decks consist of simply supported spans, which are interconnected with steel linkage bars. The main purpose of the bars is to restrain and prevent the bridge spans falling in an earthquake. The prediction of the forces imposed on the linkages is quite indeterminate because of the many variables that affect the response of adjacent bridge spans during strong earthquake motions. For economic reasons it is also usually not practical to make the linkages so strong that they will never fail under the strongest likely shaking. Linkage bars are therefore designed for a reasonable and practical strength, and are then detailed to yield and have large plastic extensions before failing in tension. The paper presents the results of laboratory tensile testing of a range of linkage bar types and conclusions are made regarding the most suitable bar assemblies, taking into account tensile ductility and cold temperature fracture toughness. Recommendations are made regarding methods of predicting earthquake loads in linkage system and on design detailing for linkage assemblies.