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Bristol City Docks (pre 1830s)
Bristol Docks, Bristol, UK
associated engineer
William Jessop
date  1st May 1804 - 1809, opened 1st May 1809
era  Georgian  |  category  Docks/Slipway  |  reference  ST575724
ICE reference number  HEW 861
The port at Bristol is subject to the huge tidal range of the River Avon. William Jessop's imaginative new dock system, known as the Floating Harbour, greatly enlarged the city's port facilities in the early 1800s by overcoming the tidal limitations — and underwriting the city's 19th century prosperity. The project was one of the greatest civil engineering undertakings of its day. Later enlarged further, the Bristol Docks are still in use, although mainly for leisure purposes.
Bristol lies at the confluence of the rivers Avon and Frome, around 12km upstream of point where the Avon flows into the River Severn. The Severn Estuary has the world’s second highest tidal range, and the water level at Bristol can change some 12m per tide. Before the 13th century, cargo ships had to be of robust construction to withstand their inevitable beaching at low tide.
Construction of a sophisticated dock system began in the mid-13th century, centred around a channelised section of the River Frome. This increased the city’s ability to trade, and Bristol developed into a thriving port despite the tidal range and the city's distance from the sea. Broad Quay (ST585727) was the first element constructed.
In 1765, engineer John Smeaton (1724-1792) proposed the creation of a non-tidal harbour. Other ideas were suggested in 1767-8 by William Champion (1710-89) and his brother John Champion (1705-94), and in around 1793 by William Jessop (1745-1814). None of the proposals were acted upon.
However, in 1802 Jessop was asked to bring all the plans together. He designed a a long harbour with two basins and a series of locks. The scheme provided an area that would be in water at all states of the tide, enabling vessels to remain afloat — hence the name Floating Harbour.
The initial scheme focused an area that ran from Hotwells (near the site of the ferry across the Avon at Rownham) east to Prince Street. The proposal adopted extended the waterway further east to Temple Meads.
An enabling Act of Parliament was passed in 1803, and the Bristol Docks Company was formed. Construction commenced at Wapping on 1st May 1804, with Jessop’s son Josias Jessop (1781-1826) as resident engineer. Three further Acts were granted in 1807-9, to raise additional share capital up to a total of £600,000, though dividends were not paid until 1823.
To construct the harbour, the Avon had first to be diverted, allowing it to flow independently of the port facilities. The river was temporarily dammed at a point between Temple Meads and Totterdown, a site that was just below the furthest upstream of the Frome's two points of entry to the Avon. A second dam was made 3.2km downstream, at Rownham. The Frome's second confluence lay between the two sites.
Between the dams, New Cut, a trench 3km long and 36.6m wide at the surface, was dug to reroute the Avon south of its natural line, leaving an isolated loop of the original river course. This loop, with the Frome flowing into it, became the Floating Harbour. It accommodated up to 1,400 vessels and covered 33.6 hectares — the largest area of water impounded for docks at that time. The excavation was on a colossal scale, with 596,831 cu m of earth and rock removed in the first year alone.
A 1.8km feeder canal was dug from a weir (ST616726) on the Avon at Netham directly east to a barge lock (ST599723) on the Avon at Totterdown. At Netham, a lock (ST615727) provides access from the harbour to the canal. An overfall dam (ST572721) with sluices at the Rownham (western) end maintained a constant water depth of 4.9m inside the harbour, or 6.7m above low water level at Rownham. The feeder canal acts as an additional source of water.
Large ships enter the dock system at the western end, from the Avon into the half-tidal Cumberland Basin, which is furnished with two entrance locks (ST567723). The northern one is 13.7m wide, the southern was 10.1m wide (enlarged in 1849). Connection into the main harbour is provided by a 13.7m wide junction lock (ST571722) at the south east corner of Cumberland Basin.
Near Wapping, between the harbour and the Avon's New Cut, Bathurst Basin was formed by enlarging the mill pond at Trin tidal mills. The Floating Harbour links to the New Cut via Bathurst Basin, with a barge lock (ST587722) at the basin's northern end. The basins and lock chambers were constructed in stone, with lock gates in timber.
Ships sailed up the Avon on a rising tide and passed into Cumberland Basin, where the river locks remained open until high tide. They could then move through the junction lock and into the harbour, where they were manoeuvred to a berth by row boats or towing horses. Small vessels could sail past the harbour entrance and continue up the Avon on the tidal New Cut.
As part of the scheme, two shallow-arch cast iron road bridges were constructed over the New Cut. Harford’s Bridge (ST589720) carried Bedminster Parade, and Hill’s Bridge (ST596722) Bath Road. Both were erected around 1805. Harford’s Bridge was replaced by the present Bedminster Bridge in 1883 (rebuilt 1998). Hill’s Bridge collapsed in 1855, after a coal barge collision, and was replaced by a 30.5m span wrought iron girder bridge.
In January 1809, the Avon was diverted into the New Cut. On 2nd April the same year, the first vessels passed through the western half of the Floating Harbour and entered Bathurst Basin. The works were completed on 1st May, an event celebrated by a feast for 1,000 of the labourers that included two whole roast oxen and 4,546 litres of beer. The final construction cost was £590,014.
By the 1830s, the harbour was noticeably getting clogged with silt, causing difficulties for the docking of ships with deep drafts. The problem was solved by Isambard Kingdom Brunel (1806-59), who designed new sluices and locks. Brunel made further harbour improvements in the 1840s, as did Thomas Howard (1816-96) in the 1870s and John Ward Girdlestone (1840-1911) in the 1880s. These works are the subject of a separate article.
Some of Jessop's surviving structures are Grade II listed — the south junction lock between Cumberland Basin and the Floating Harbour (February 1972, now blocked at its western end), Cumberland Basin and Bathurst Basin (March 1977), and Netham Lock (July 1990).
Resident engineer: Josias Jessop
Contractor (excavation and stonework): Thomas Thatcher and others
Lock machinery: John Armstrong
Cast iron bridges: Coalbrookdale Company
Research: ECPK
"The Annals of Bristol in the Nineteenth Century" by John Latimer, W & F Morgan, Bristol, 1887
reference sources   BDCE1CEH W&W

Bristol City Docks (pre 1830s)