Northam Bridge
Encyclopedia
The Northam Bridge is a road bridge
across the River Itchen
in Southampton
, England
, linking the suburbs of Northam and Bitterne Manor
. The current bridge was the first major prestressed concrete road bridge to be built in the United Kingdom
. The bridge carries the A3024 road as a dual carriageway
, with two lanes on each carriageway.
. Mansbridge was the lowest crossing point of the river until the early 18th century, when the Itchen Ferry began operating between Woolston and St Mary's, downriver of Northam.
The Northam Bridge was the brainchild of David Lance, who acquired land in Bitterne
and built Chessel House there in 1796. Realising that access to his land was poor, he encouraged the building of a bridge linking Bitterne Manor to Northam, together with roads from the bridge to Botley
and a further bridge over the River Hamble
in Bursledon
(and onwards to Portsmouth
), with the fork between the Bursledon and Botley roads passing close to Chessel House. The Northam Bridge Company was formed in 1796, funded mainly by Portsmouth businessmen.
The new route between Portsmouth and Southampton would be four miles (6 km) shorter than travelling via Mansbridge, and as a result the proposal to improve transport between the two important port cities was keenly supported by the Admiralty
, especially since this was the time of the Napoleonic Wars
. Consequently when the Northam Bridge Company sought an Act of Parliament
to build a bridge, the Act was passed quickly.
The new roads and bridges were built in 1799, and were originally operated as toll road
s. The first Northam Bridge was of wooden construction. The wooden bridge was replaced in 1889 by an iron bridge.
The bridge remained a toll bridge
until 1929 when the ownership was transferred from the private sector
to the Southampton Corporation.
It was this change of ownership that allowed the first bus
route across the River Itchen to be established in Southampton; Southampton Corporation decided against extending the existing tram
lines across the bridge, opting instead to establish a double-decker bus
service.
The iron bridge was replaced in 1954 with a third bridge, made of prestressed concrete
, and it is this bridge that still stands today. The third Northam Bridge was the first major prestressed concrete road bridge to be built in the UK.
era. The main deck structure has transverse
diaphragm
s and narrowly spaced beams, which were pre-cast on site using deflected cables. Pre-cast, pre-stressed slabs, known as junction slabs or continuity slabs, were placed between the tops of the beams by transverse stressing over a length where the flanges of the tees were removed. These, together with in situ
diaphragms between the ends of the beams, allowed the deck structure to be made continuous for live and superimposed loads. After the junction slabs were in place, the main beams were post-tensioned through the diaphragms.
At mid-span, the bridge is 44 in 4 in (13.51 m) wide, 4.7 metres above mean high water springs
and 9.2 metres above chart datum
. The bridge is 148 metres long in total, and the supporting piers are up to 32 metres apart.
Bridge
A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
across the River Itchen
River Itchen, Hampshire
The River Itchen is a river in Hampshire, England. It flows from mid-Hampshire to join with Southampton Water below the Itchen Bridge in the city of Southampton. The river has a total length of , and is noted as one of England's - if not one of the World's - premier chalk streams for fly fishing,...
in Southampton
Southampton
Southampton is the largest city in the county of Hampshire on the south coast of England, and is situated south-west of London and north-west of Portsmouth. Southampton is a major port and the closest city to the New Forest...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, linking the suburbs of Northam and Bitterne Manor
Bitterne Manor
Bitterne Manor is a suburb of Southampton surrounding the manor house of the same name.- History :Bitterne Manor is the site of the original Roman settlement of Clausentum, the forerunner to today's City of Southampton....
. The current bridge was the first major prestressed concrete road bridge to be built in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
. The bridge carries the A3024 road as a dual carriageway
Dual carriageway
A dual carriageway is a class of highway with two carriageways for traffic travelling in opposite directions separated by a central reservation...
, with two lanes on each carriageway.
History
Prior to the construction of the Northam Bridge, the southernmost bridge across the River Itchen was at MansbridgeMansbridge
Mansbridge is a suburb on the northern perimeter of Southampton, England. The area is named after the Mans Bridge which spans the River Itchen. For a considerable time, this was the southern-most crossing point of the river, before the construction of Woodmill in Swaythling...
. Mansbridge was the lowest crossing point of the river until the early 18th century, when the Itchen Ferry began operating between Woolston and St Mary's, downriver of Northam.
The Northam Bridge was the brainchild of David Lance, who acquired land in Bitterne
Bitterne
Bitterne is an eastern suburb and Electoral Ward of Southampton, England.Bitterne derives its name not from the similarly named bird, the Bittern but from the bend in the River Itchen; the Old English words byht and ærn together mean "house near a bend", most likely a reference to Bitterne Manor...
and built Chessel House there in 1796. Realising that access to his land was poor, he encouraged the building of a bridge linking Bitterne Manor to Northam, together with roads from the bridge to Botley
Botley, Hampshire
Botley is a historic village in Hampshire, England that obtained a charter for a market from Henry III in 1267. The area has been settled since at least the 10th century....
and a further bridge over the River Hamble
River Hamble
The River Hamble is a river in Hampshire, England. It rises near Bishop's Waltham and flows for some 7.5 miles through Botley, Bursledon and Swanwick before entering Southampton Water near Hamble-le-Rice and Warsash....
in Bursledon
Bursledon
Bursledon is a village on the River Hamble in Hampshire, England. It is located within the borough of Eastleigh. Close to the city of Southampton, Bursledon has a railway station, a marina, dockyards and the Bursledon Windmill. Nearby villages include Swanwick, Hamble-le-Rice, Netley and Sarisbury...
(and onwards to Portsmouth
Portsmouth
Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...
), with the fork between the Bursledon and Botley roads passing close to Chessel House. The Northam Bridge Company was formed in 1796, funded mainly by Portsmouth businessmen.
The new route between Portsmouth and Southampton would be four miles (6 km) shorter than travelling via Mansbridge, and as a result the proposal to improve transport between the two important port cities was keenly supported by the Admiralty
Admiralty
The Admiralty was formerly the authority in the Kingdom of England, and later in the United Kingdom, responsible for the command of the Royal Navy...
, especially since this was the time of the Napoleonic Wars
Napoleonic Wars
The Napoleonic Wars were a series of wars declared against Napoleon's French Empire by opposing coalitions that ran from 1803 to 1815. As a continuation of the wars sparked by the French Revolution of 1789, they revolutionised European armies and played out on an unprecedented scale, mainly due to...
. Consequently when the Northam Bridge Company sought an Act of Parliament
Act of Parliament
An Act of Parliament is a statute enacted as primary legislation by a national or sub-national parliament. In the Republic of Ireland the term Act of the Oireachtas is used, and in the United States the term Act of Congress is used.In Commonwealth countries, the term is used both in a narrow...
to build a bridge, the Act was passed quickly.
The new roads and bridges were built in 1799, and were originally operated as toll road
Toll road
A toll road is a privately or publicly built road for which a driver pays a toll for use. Structures for which tolls are charged include toll bridges and toll tunnels. Non-toll roads are financed using other sources of revenue, most typically fuel tax or general tax funds...
s. The first Northam Bridge was of wooden construction. The wooden bridge was replaced in 1889 by an iron bridge.
The bridge remained a toll bridge
Toll bridge
A toll bridge is a bridge over which traffic may pass upon payment of a toll, or fee.- History :The practice of collecting tolls on bridges probably harks back to the days of ferry crossings where people paid a fee to be ferried across stretches of water. As boats became impractical to carry large...
until 1929 when the ownership was transferred from the private sector
Private sector
In economics, the private sector is that part of the economy, sometimes referred to as the citizen sector, which is run by private individuals or groups, usually as a means of enterprise for profit, and is not controlled by the state...
to the Southampton Corporation.
It was this change of ownership that allowed the first bus
Bus
A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...
route across the River Itchen to be established in Southampton; Southampton Corporation decided against extending the existing tram
Tram
A tram is a passenger rail vehicle which runs on tracks along public urban streets and also sometimes on separate rights of way. It may also run between cities and/or towns , and/or partially grade separated even in the cities...
lines across the bridge, opting instead to establish a double-decker bus
Double-decker bus
A double-decker bus is a bus that has two storeys or 'decks'. Global usage of this type of bus is more common in outer touring than in its intra-urban transportion role. Double-decker buses are also commonly found in certain parts of Europe, Asia, and former British colonies and protectorates...
service.
The iron bridge was replaced in 1954 with a third bridge, made of prestressed concrete
Prestressed concrete
Prestressed concrete is a method for overcoming concrete's natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete...
, and it is this bridge that still stands today. The third Northam Bridge was the first major prestressed concrete road bridge to be built in the UK.
Construction and dimensions
The third bridge utilised the latest technology available at the time but the style of the bridge was of the pre-warWorld War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
era. The main deck structure has transverse
Transversality
In mathematics, transversality is a notion that describes how spaces can intersect; transversality can be seen as the "opposite" of tangency, and plays a role in general position. It formalizes the idea of a generic intersection in differential topology...
diaphragm
Diaphragm (structural system)
In structural engineering, a diaphragm is a structural system used to transfer lateral loads to shear walls or frames primarily through in-plane shear stress...
s and narrowly spaced beams, which were pre-cast on site using deflected cables. Pre-cast, pre-stressed slabs, known as junction slabs or continuity slabs, were placed between the tops of the beams by transverse stressing over a length where the flanges of the tees were removed. These, together with in situ
In situ
In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...
diaphragms between the ends of the beams, allowed the deck structure to be made continuous for live and superimposed loads. After the junction slabs were in place, the main beams were post-tensioned through the diaphragms.
At mid-span, the bridge is 44 in 4 in (13.51 m) wide, 4.7 metres above mean high water springs
Mean high water springs
The mean high water spring is the highest level that spring tides reach on the average over a period of time . This level is generally close to being the "high water mark" where debris accumulates on the shore annually.-External links:...
and 9.2 metres above chart datum
Chart datum
A chart datum is the level of water that charted depths displayed on a nautical chart are measured from. A chart datum is generally a tidal datum; that is, a datum derived from some phase of the tide...
. The bridge is 148 metres long in total, and the supporting piers are up to 32 metres apart.