 The PDR has been constructed in separate link roads of between 1 @.@ 61 km ( 1 @.@ 00 mi ) and 5 @.@ 47 km ( 3 @.@ 40 mi ) around Cardiff and to date 22 kilometres ( 14 mi ) including spurs have been opened to traffic , with plans for a further 5 @.@ 53 km ( 3 @.@ 44 mi ) . It has 4 large <unk> ( Ely Viaduct , Grangetown Viaduct , Taff Viaduct and the East Moors Viaduct ) , 1 tunnel ( Queen 's Gate Tunnel ) and 2 spur roads ( Cogan Spur and Central Link Road ) . The road also has many smaller bridges over or under most of the interchanges on the road . The entire length of the road has <unk> restrictions on it . 
