The Canterbury Association survey of Christchurch in 1850 laid out the nascent town in a grid, bisected only by diagonals providing access to the port of Lyttelton and the northern hinterland. Disrupting the regularity of this street pattern however were the sinuous curves of the Avon River. These proved a serious impediment to travel within the city, and necessitated the prompt construction of a series of bridges. Initially simple structures, by the 1880s the majority of these inner city bridges had been replaced in permanent materials. With their fine cast iron railings, they contribute much to the townscape and character of Christchurch. A suspension footbridge was erected at the Gloucester St crossing of the Avon in 1862. Gothic in style to match the adjacent Provincial Government Buildings, the bridge may also have been designed by B.W. Mountfort. In 1886-7 it was replaced with a new iron road bridge at a cost of £1, 888. This bridge was designed by City Surveyor Charles Walkden, and built by William Stocks. Walkden gave the City Council two options for the railing pattern; that selected was identical to the Victoria St Bridge. The ironwork was fabricated by Scott Bros. In 1936 the City Council decided to widen the bridge 14 ft. on the south side, making it level with the building line on that side of the street. The work was carried out in 1937, with the original Mt Somers stone wing walls and piers being replaced in concrete. Surveyor and engineer Charles Walkden (1824-1908) had worked in Austria and Denmark for a number of years before arriving in Christchurch in 1871. In 1874 he was appointed City Surveyor to the City Council, a position he held for 22 years. During this time, Walkden was responsible for building or rebuilding many of the bridges in central Christchurch. He retired in 1896 on an allowance of £375 p.a. William Stocks (1837-94) was born in Huddersfield, England, coming to the Otago goldfields in 1858. He became a building contractor in Dunedin, and continued in this work after moving to Christchurch in 1878. He was responsible for many important public buildings and works in Canterbury, including the Waimakariri Gorge Bridge, the Hurunui Bridge, and a number of railway lines.