page_title: Trinity Chain Pier
section_title: Design
hierarchical_section_title: Trinity Chain Pier / Design
caption_attribution_description: English: Plaque on the stone anchorage inside the Old Chain Pier pub.
context_page_description: Trinity Chain Pier, originally called Trinity Pier of Suspension, was built in Trinity, Edinburgh, Scotland in 1821. The pier was designed by Samuel Brown, a pioneer of chains and suspension bridges. It was intended to serve ferry traffic on the routes between Edinburgh and the smaller ports around the Firth of Forth, and was built during a time of rapid technological advance. It was well used for its original purpose for less than twenty years before traffic was attracted to newly developed nearby ports, and it was mainly used for most of its life for sea bathing. It was destroyed by a storm in 1898; a building at the shore end survives, much reconstructed, as a pub and restaurant called the Old Chain Pier.
context_section_description: The pier was proposed by Lieutenant George Crichton of the London, Leith, Edinburgh and Glasgow Steam Navigation Company. In 1820 the Lord Provost and magistrates of Edinburgh granted the company permission for the pier's construction. The company then transferred the permission to the Trinity Pier Company who were to administer construction and operate the pier, and they in turn commissioned Captain Samuel Brown to design the pier as his first independent project. Alexander Scott WS, one of the trustees of the company, granted permission to build the pier on his land. Scott and Alexander Stevenson were directors of the Trinity Pier Company, and Crichton was treasurer. It cost £4000 to build.
  Brown (1776–1852) was a veteran of the Napoleonic Wars and had taken part in the capture of a superior French ship in 1805. He patented his method of building suspension bridges in 1817. He designed the extant 1820 Union Bridge near Berwick-upon-Tweed, which was the biggest suspension bridge in the world when built, and the first in Britain to carry vehicles.
  While serving in the Royal Navy, Brown had experimented with using chain instead of rope in rigging sailing ships, and in 1808 he patented a new kind of wrought-iron chain. He sold the design to the Admiralty, which used it as anchor cable on ships. Brown considered that using piles to support a pier was superior to the traditional method of building in stone, because it was more economical to build and easier for ships to dock with. He cited pile-supported piers at Yarmouth, Ostend and Kronstadt which had been successful for long periods based on this design. Brown had used chains in his designs for some of Britain's first suspension bridges; he realised that chains made out of eye bolts joined together were stronger than traditional designs based on shorter links. He was regarded as a "leading promoter" of suspension bridges. He proposed that suspension piers could support military and rescue operations. On 14 August 1822 Brown married Mary Horne from Edinburgh. After the pier at Trinity he went on to build the similar but much larger Royal Suspension Chain Pier in Brighton in 1823. It was destroyed by a storm in 1896.
  The pier was 700 feet (210 m) long with a 4-foot-wide (1.2 m) passenger deck. This comprised three  209-foot-long (64 m) wooden spans suspended 10 feet (3.0 m) above high water from lengths of wrought-iron chain connecting cast-iron standards to the shore. Each standard was in the shape of an arch which the passengers walked through. By 1838 the passenger deck had rails fitted to assist in moving large items of luggage. The chain was made of eye bolts about 10 feet (3.0 m) long, which, uniquely among Brown's designs, varied in thickness according to the load they were expected to carry. The long eye bolts were joined by shorter linking plates, and hung in a catenary 14 feet (4.3 m) from the tops of the standards. The chains crossed the standards on cast-iron saddles. The three seaward standards were built on platforms anchored to wooden piles driven into the foreshore. The largest platform, which formed the head of the pier, was 60 feet (18 m) by 50 feet (15 m), and covered in 2-inch (51 mm) thick planks. The length of the pier head was extended to 70 feet (21 m) prior to November 1821. It was supported on 46 piles driven 8 feet (2.4 m) into the clay seabed. At the landward end the chain passed over a solid masonry construction, 6 feet (1.8 m) square and 20 feet (6.1 m) high, and was then anchored at a 45° angle 10 feet (3.0 m) into the hard clay soil. The seaward end of the chain went over the outer piles at the same angle, and the piles were braced with diagonal supports to take the sideways load. There was a 4-foot-high (1.2 m) wrought-iron railing along the length of the deck, straight diagonal members connecting the deck to the standards, and iron bracing under the deck. The pier was designed for passenger use only, and moved noticeably when walked on.
  Brown tested the pier on 21 September 1821 by having 21 tons of pig-iron ballast placed on the spans whil
caption: Plaque on the stone anchorage inside the Old Chain Pier pub
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