Ibsley Bridge
This very attractive bridge over the River Avon was originally built in 1797 with a single semi-elliptical stone arch spanning 40ft. In 1930 the arch was completely rebuilt from the foundations to the same dimensions together with two additional 25ft-long segmental side-arches and small rounded cutwaters at each end of the two piers. The bridge is now about 24ft wide. The solid masonry parapet, which sits on a string course marking the road level, has a recessed panel over the central keystone and terminates in small circular piers. The Avon Valley Path passes the south-west end of the bridge. ABSE, BB, BHHI
Ibsley Bridge
The bridge over Iffley Lock is a replica of the 1750 Mathematical Bridge at Cambridge (qv) and was built by the Thames Conservancy in 1923. The Thames Path runs past the western side of the lock.
The existing old crossing over the River Stour is in three parts. At the eastern end are four brick and two stone flood relief arches, probably built in the late eighteenth century. The central oldest part, with a roadway only 13ft wide, consists of four semicircular stone arches spanning 12ft between piers with pointed cutwaters, and dates from the middle of the seventeenth century. The first two arches of the western part, over the main river channel, are segmental stone arches spanning 30ft and were built in 1784. In 1933, following the complete re-alignment of the road a short distance upstream, a further two matching arches were built at the eastern end of these eighteenth-century spans, and all three of the bridges were restricted to pedestrians only. The new bridge over the river channel is in engineering brick and has a central 35ft semi-elliptical main span and two semicircular side spans; there are also ten smaller flood arches. The Stour Valley Way passes the south-west end of the bridge. ABSE, BB, BiB, DDB, Young
Iford Bridge (1784)
The present bridge at Ilchester, built in 1825, is the third to be recorded that crosses the River Yeo at this point. The first, probably dating from around 1400 and seen by Leland in the sixteenth century, was a seven-arched stone structure on which stood two small stone buildings, one being the local gaol and the other what had once been a chapel. By the eighteenth century the bridge had presumably been rebuilt, as it was described as having just two arches. The existing structure has seven small semicircular spans varying in length from 8ft to 12ft. In 1932 the bridge was widened by 10ft to 23ft, with the arches strengthened and extended in concrete but refaced with the original stonework. ABSE, BB, JLI,
Ilchester Bridge
There have been several bridges across the River Wharfe in Ilkley, with a record of the first dating back to the mid-fifteenth century. Another newly built bridge fell in 1638 and in 1673 its replacement was also swept away. The present handsome structure was built in 1678. It is 13ft wide and has three bold segmental arches spanning 30ft, 50ft and 30ft, giving it a humpbacked appearance with steep approaches to the crown. There are also bold triangular cutwaters with sloping caps at each pier. The Ebor Way runs along the south bank of the Wharfe just west of the bridge. ABNE, BiB, BME, JBPT, SYBBR
The opening bridge at Inchinnan is the only Scherzer rolling lift bascule of its kind still operating in Scotland. It was built in 1923 to replace an earlier swing bridge as part of a scheme to widen the navigable Black Cart River to 90ft, and now carries the A8. It was refurbished in 2004 and is Grade A listed.
The distinctive new footbridge over the River Tees, opened in 2009, consists of two unequal steel bowstring arches, spanning 120m and 60m, but with the arches also linked by a reversed curve section above the river pier to give a flowing M-shaped elevation. Together, the bridge and its reflection thus look like the lemniscate symbol ∞ introduced by John Wallis in 1655 to represent the concept of infinity. Steel cross beams hung from the arches support a slim 5m-wide precast concrete deck. The bridge, which was designed by Expedition Engineering, received the Institution of Structural Engineers Supreme Award for Structural Engineering Excellence in 2009. The Teesdale Way passes the north end of the bridge. BTe, NCE
Infinity Bridge
This 90ft-span Warren girder bridge carries a 9½ft-wide roadway and was built in 1931 to replace an earlier timber structure. It is interesting as a rare example of a temporary military bridging system, which was developed during the First World War by Sir Charles Inglis and superseded by the later Bailey Bridge. It consists of six triangular A-frames made up of tubular members slotted into cast connecting pieces. CEHW
Inglis Bridge
Inveraray Castle was built in the Scottish Baronial style by the architect Roger Morris for the Duke of Argyll between 1745 and 1758. It is approached from the south-west over a dry moat by a stone bridge consisting of two pointed arch spans, with the intermediate pier also in the form of a pointed arch. The structure is now enclosed by a glass canopy.
In addition, apart from the nearby Aray Bridge (qv) carrying the A83, the gardens and estate are graced by three very attractive bridges, all listed Grade A. The Garron Bridge was built in 1748 to carry the old military road across the River Garron at the head of Loch Shira. It, too, was designed by Roger Morris, who ornamented the structure so that it could be a focal point of views from the castle. It has a single, high segmental stone arch spanning about 40ft and there is a solid, level parapet over the bridge crown, with sloping balustrades between this and the tall semi-hexagonal abutments that are topped by stone spheres. There is now a modern bypass bridge.
Inverary Castle, Garron Bridge
John Adam designed the handsome Garden (or Frew’s) Bridge over the River Aray just north of the castle, built by David Frew in 1761. Its semi-elliptical arch spans a then record-breaking 60ft and has an elegant balustrade on a dentilled string course. There is an archivolt outside the double arch ring and the masonry in the spandrels is laid radially, apart from in the centre of a blind oculus at each end.
Inverary Castle, Frew’s Bridge
The third bridge, by Robert Mylne, is the Dubh Loch Bridge carrying an estate road over the River Garron, built in 1785. It has a single 60ft-span segmental stone arch, its double ring of voussoirs diminishing in depth from abutments to crown. The parapet stands on a dentilled string course and is pierced by several medieval-style combination defensive loopholes. The abutments, continuing the fortified theme, are castellated. ABTB, BPJ, CEHSH, HB, NTBB
Joseph Mitchell built this handsome bridge in 1867 to carry the tracks of the Sutherland Railway over the River Carron. It has two segmental stone arches spanning 45ft and 55ft. BHRB, HB, RHB
Old Invercauld Bridge, listed Grade A and now cared for by Historic Scotland, was built in 1755 during improvement work to General Wade’s earlier military roads. With a 14ft-wide deck, it has six segmental stone arches, the largest of which spans 66ft and is the second in from one end, giving a slightly lopsided look to the sloping parapet walls. The piers are protected by massive triangular cutwaters. In 1859 the bridge and road became part of the Balmoral estate and New Invercauld Bridge was built, at his own expense, by Prince Albert. This has three main stone arches. The bridge was severely damaged by floods in December 2015. BB, BiB, BPJ, HB
Invercauld Old Bridge
The first suspension bridge over the River Irfon, just upstream from where it joins the Wye, was brought from Glanusk (qv) and rebuilt here in 1839 as a gift to the town from the previous owner Sir Joseph Bailey. It was repaired in 1868 and replaced by a stayed footbridge in 1983, which now carries the Wye Valley Walk.
Iron Bridge over the River Severn at Coalbrookdale, one of the first ever bridges to be built of cast iron, is a bridge of worldwide importance. Designed by the architect Thomas Farnolls Pritchard and built by ironmaster Abraham Darby III, it consists of five semicircular arch ribs, of rectangular cross section measuring six inches by nine inches, that span 100ft and support a 24ft-wide deck. The ribs were cast in halves, with each 70ft-long piece weighing nearly six tons. Above these main ribs, and linked to them by radial members, there are two successively shorter ribs, the spandrel space between these and the deck being filled with decorative iron circles and tall ogee-shaped arches. The bridge was opened on 1 January 1781. As a result of movement in the valley sides, the solid stone walls supporting the approaches behind the south abutment were replaced by timber land arches in 1804, and these by iron arches in 1823. Between 1972 and 1979, in a big programme of work to safeguard the bridge against further movement, a reinforced concrete invert slab was placed below the riverbed between the abutments, and filling within the abutments was removed to leave a hollow masonry box, the roadway over the top being carried on a new concrete deck supported on precast concrete beams. The bridge deck, too, was waterproofed and new surfacing laid. The bridge, which is listed Grade I, now carries pedestrians only and is a major point of interest on three marked walks – the Cross Britain Way, the Severn Way and the Shropshire Way. ABTB, BA, BB, BBPS, BE, BEVA, BFB, BME, BoB, BOTB, CAB, CEHWW, CoB, DB, DoB, DoD, FFB, HBS, IB, NPB, TWCIB, Cossons, Innides, Smith
Iron Bridge, Ironbridge
This 25ft-wide six-span cast iron bridge, completed in 1836, carries the Barnstaple road out of Exeter over the Long Brook. Each of the five intermediate piers consists of three delicate cast iron columns supporting a cross beam that, in turn, supports the ends of the six arched ribs spanning 40ft, their spandrels lightened by cast circles with inset quatrefoils. The cast iron decking plates were replaced in 1985 by a reinforced concrete deck. CEHS
Iron Bridge, Exeter
This medieval long bridge over the River Nene, probably dating from the fourteenth century, has ten main pointed stone arches and nine further arches on the bridge approaches, the main bridge being about 270ft long. The spans of these arches vary from 10ft to 14ft and some of them have chamfered arch rings and narrow ribs. The carved date 1668 on one of the cutwaters presumably records some kind of repair work carried out then. The bridge, which was originally 10ft wide, was widened on the eastern side in 1754 to about 16ft with brick arch extensions on its upstream side, and the approaches and flood arches were widened in 1908. The cutwaters and refuges on the downstream side remain. The bridge is listed Grade I and in 1936 was bypassed by a new structure carrying the A5 and under which the Nene Wye now passes, from which there are good views of the medieval bridge. ABMEE, BB, BME, NTBB, SC
Irthlingborough Bridge
The single 200ft-span M62 Irwell Valley road bridge has seven 11ft-deep trapezoidal box girder beams supporting a reinforced concrete deck slab. The box girders were delivered to site in 50ft-long sections, then welded together for launching across the river. The bridge was completed in 1969. ICE
Built in 1965, this bridge carries the A423 Oxford ring road over the Thames to the south of Oxford. The concrete deck is supported by ten parallel steel plate girders, each of which is a continuous three-span beam with curved soffits. The central span of 135ft is flanked by 62ft-long side spans. BoT, TBDS
In 1833 a company was formed to build a bridge at this site, about one mile below the main crossing at Northam Bridge (qv), to replace the ancient and traditional ferry service that provided the lowest crossing over the tidal River Itchen. In 1836, however, a floating bridge chain ferry opened here instead and it was not until 1977 that a fixed structure was finally completed. This two-lane toll bridge, designed by Travers Morgan & Partners, has five main spans – three central spans each 410ft long and providing 80ft clearance at high water over the central 100ft, flanked at each end by a 262ft-long span – with approach viaducts on both banks. It is a prestressed concrete balanced cantilever structure with precast suspended sections in the three central spans. BEVA, Adams
Itchen Bridge
Ivelet Packhorse Bridge over the River Swale is an attractive segmental stone arch spanning about 60ft that is known as the ‘Queen of Swaledale Bridges’. Although now carrying a roadway, the bridge is only just over 8ft wide between parapets. The bridge, built in 1695, was on the route of an old ‘corpse way’, and a large stone near the north end was where the coffins were rested. The bridge is now crossed by the Pennine Journey walk. BBPS, JBPT, PBE, SYBBR
Ivelet Bridge
The original viaduct at Ivybridge was one of five similar structures built by Brunel in 1848 to carry the South Devon Railway’s single broad-gauge track between Totnes and Plymouth. They are of historic interest since he specially designed them to carry the ‘atmospheric railway’ system in which the train was propelled by the pressure of the atmosphere acting on a piston moving within a tube exhausted by trackside pumps. Since the train itself required no engine, this meant that the live loadings were much lower than for locomotives and the structures could therefore be correspondingly lighter. Ivybridge Viaduct had eleven timber spans standing on slim masonry piers that were 109ft high and consisted of twin columns linked by wrought iron ties. Each 10ft-long span was supported by four struts radiating from thrust blocks near the pier tops. However, within six months the atmospheric system was abandoned and the timber structure had to be greatly strengthened by the addition of a trussed timber parapet, and the whole superstructure was completely replaced by wrought iron girders in 1861. The viaduct was then rebuilt in 1893 to carry standard-gauge double tracks. BHRB, BRBV, BTBV, DB, RHB
Ivybridge (Erme) Viaduct