Inner Tay Estuary viridis" - a species normally found only in north-eastern North America. Scottish Natural Heritage has commissioned and published habitat survey reports for the Inner Tay Estuary. Public roads run within a few hundred metres of the both north and south shores providing easy access to view the estuary and its wildlife, though car parking is limited in many places: (south shore) Wormit, Balmerino, Newburgh, Elcho Castle; (north bank) Riverside Drive in Dundee by the railway bridge, Invergowrie, Kingoodie, Port Allen, Powgavie, Cairnie Pier; (in Perth) from both banks, the bridges, Moncreiffe Island; (in Bridge of Earn) the bridge. The minor
Tay Bridge disaster were now constructed by sinking brick-lined wrought-iron caissons onto the riverbed, and filling these with concrete. To reduce the weight these had to support, Bouch used open-lattice iron skeleton piers: each pier had multiple cast-iron columns taking the weight of the bridging girders. Wrought iron horizontal braces and diagonal tiebars linked the columns in each pier to provide rigidity and stability. The basic concept was well known, but for the Tay Bridge, the pier dimensions were constrained by the caisson. For the higher portion of the bridge, there were 13 girder spans. In order to accommodate thermal expansion, at only