The first "true" extradosed design on the continent is the North Arm Bridge at Vancouver, British Columbia, Canada, which spans and was completed in 2008. Since the mid-2000s the style has grown appreciably in popularity with over fifty bridges with extradosed characteristics being recorded as of 2012. They have been constructed in many countries, although the significant majority of them are located in Japan and South Korea. The longest-span example remains the 2001 Kisogawa Bridge at . Design characteristics Visually, extradosed bridges typically have the appearance of a cable-stayed bridge with very short towers (pylons), with cable stays of shallow angle that may not extend along the full length of the deck, and (frequently) with a more substantial deck superstructure. Developed as a hybrid structure between the classic cable-stay and cantilever-girder bridge types, they can offer cost saving and aesthetic opportunities for medium-length bridges in the to span range. Their hybrid nature can lead to significant additional complexity in their design, as the response of the bridge to applied loads is determined by the interactions between: the flexural stiffness of the deck/girder superstructure; the axial stiffness of the cable stays; the height and longitudinal stiffness of the towers/pylons; the lengths of adjacent spans and back-spans; the degree of fixity between the superstructure, the towers and the substructure; the flexural stiffness of the main support piers. Although differentiated from cable-stayed bridges in a number of areas, the principal and defining extradosed characteristic is the low height of the main towers or pylons, expressed as a proportion of the main span length. Classic cable-stayed designs employ a tower-height to main-span ratio of around 1:5 (or 0.20). In comparison, extradosed bridges have towers with height:span ratios of between 1:8 and 1:15 (0.125 to 0.067), with around 1:10 (0.10) being most common. This lower tower height results in a much flatter cable angle, typically ~ 17° to the horizontal, and a correspondingly much higher axial compression force within the bridge superstructure due to the greater horizontal force component within each cable stay. From a structural perspective, the second extradosed characteristic is the reduced proportion of superstructure live load that is carried by the cables. On cable-stayed bridges, the stays commonly support at least 80% of the loading from vehicular traffic acting on the bridge superstructure, whereas on extradosed bridges, the stay cables typically support only between 20% and 60% of this load. In both