arch blue bridge centre city contemporary cross dundee footpath glass modern over pedestrian rail railway span steel stylish tracks walk walkway architecture cloud coastline cumbria England english estuary Great Britain landmark landscape Morecambe Bay nature sandflats shore sky viaduct view water Barmouth Causeway gantry girders hills iron line mountains perspective planks resort sea shadows vanishing point wales walkers welsh wooden cantilever crossing Edinburgh engineering Forth girder metal river scotland scottish ship tanker train trains