[ As to the name "Black Bridge" I notice that the old name for the big wood to the east of Nuneham Park used to be "Black Wood". The railway goes nowhere near it, but maybe the wood for the first bridge came from there? I recently met a Radley rowing man who knew the bridge under this name. ]
The bridge has, it seems, a very similar history to Appleford Railway Bridge (which is only a mile or so down the line, though much further by water). As with Appleford Bridge I can so far find no picture of the 1844 original.
1843: Isambard Kingdom Brunel drew up this design sketch for Nuneham Bridge which is far more convincing than I had previously imagined. (I had thought it would have been like the original Bourne End Bridge). In the sketch book catalogue the bridge is said to be in timber. It may of course not be the right bridge.

Nuneham Railway Bridge design sketch Brunel 1843
Nuneham Bridge, design sketch by Brunel
University of Bristol Library Special Collections: DM162/8/1/2/Small Sketchbook 18/folio 36

1844: The first bridge was built to carry the Oxford - Didcot Railway Line.
1852: Fred Thacker in 1920 said of it:

An elevation in August 1852 shews it to have been first proposed in timber. All the openings were to be 40 ft. wide

The dimension appears to match the middle design of the three in the above sketch (each tiny square being 1 foot)

1856: A second, iron, bridge built.

1859: The Thames, Mr & Mrs Hall

[ Radley Hall was built in the 1720s and became Radley College in 1847. ]

This scenery continues until we reach the modern railway bridge, [ the three year old iron bridge of 1856 ]when, on the right bank of the stream, Radley House is descried: another turn of the river, past this demesne, and the spire of Abingdon comes in view. Between Nuneham Courtenay and Abingdon the river winds so much. that when we reach this ancient town we are nearly opposite to Oxford, distant about six miles.

1882:Black Bridge, Nuneham Courtenay, Henry Taunt -

Black Bridge, Nuneham Courtenay, Henry Taunt, 1882
Black Bridge, Nuneham Courtenay, Henry Taunt, 1882
© Oxfordshire County Council Photographic Archive; HT3857

1873: from Sherwood's 'Oxford Rowing' -

1873: Coxswainless Fours were established. They were arranged to be rowed from the lasher to the island at Nuneham, as level races, but the steering was so atrocious that this latter idea was soon abandoned.
We can well remember the sorry plight of one of the crews as we saw them one day, dripping wet, and shivering in the cold wind on one of the piers in the middle of the river under Nuneham Railway Bridge; too cold to swim, and with no friendly boat in sight to take them off, and their own boat a wreck through running into the bridge;
and the steering in the other boats was nearly as bad, only they had the good fortune always to run into the bank on one side or the other.

1885: The Royal River -

It is best to see Nuneham Reach from the railway bridge. From any other point it is necessary to see the bridge itself.

1890: And here is the view taken by Frith -

Nuneham Railway Bridge View 1890
View upstream from Black Railway Bridge, 1890

1897: Second Nuneham Railway Bridge, James Dredge -

Second Nuneham Railway Bridge, James Dredge, 1897
Second Nuneham Railway Bridge, James Dredge, 1897
© Oxfordshire County Council Photographic Archive; D230160a

1906: Faringdon Advertiser and Vale of the White Hose Gazette: ACCIDENT AT BLACK BRIDGE:

An alarming and fatal accident occurred on Monday afternoon at Nuneham Railway Bridge, which crosses the Thames between Radley and Culham Stations.
For nearly twelve months workmen have been engaged in re-building the bridge, for which it was necessary to erect staging overhanging the river, and about 4.45 on Monday some of the staging gave way, and, with two men who were standing on the platform, fell into the river, a third being only saved by clinging to one of the girders.
The bridge originally built for the opening of the branch line from Didcot to Oxford in 1844 was a wooden structure.
This was replaced by an iron girder one in 1856 being the bridge which was receiving attention in the above report.
This in turn was replaced by a steel twin bow arch bridge in 1929 which is still in use.

1929:  Third and Current Nuneham Railway Bridge built in steel - a single bow structure.

1943: Start of the second unofficial Wartime Boat Race -

The Cambridge crew was a cosmopolitan one by the standards of those times with a Dane at bow and a Turk at 4. Oxford on the other hand was nationally more traditional, but had no less than 4 medical students in the crew. As on the previous occasion (1940) training was restricted to three afternoons per week for both crews.
The banks of the rather narrow 1¼ mile course (from Black Bridge to the island by Radley Boathouse) were thronged with spectators all of whom had had to reach it by either bicycle or on foot. The newspaper reports at the time speak about a crowd of between 7,000 and 10,000.
Oxford won the toss and chose the Oxfordshire bank. They set off at 40 compared to the Cambridge 37 and were in the lead almost immediately, reported as a length up in less than half a minute. Despite being left at the start, Cambridge clearly did not give up and gave a spirited response for the judge’s verdict at the finish was a win for Oxford by two-thirds of a length.

Nuneham Railway Bridge in 2002
Nuneham Railway Bridge in 2002.

[ Aren't I nicely tucked up in the reeds!  I was blown there! (And then decided I should take a photo to justify myself.) I was going to Abingdon on a windy day and somebody had taken Abingdon and made off with it.  Whole sections of river had been randomly inserted.  That two miles from Lock Wood Island to Abingdon stretched quite endlessly …]

1891: The Stream of Pleasure, Joseph & Elizabeth Robins Pennell -

All the afternoon we drifted with the stream, or lay for hours among the reeds by the banks, watching the boats. In the stillness we could hear the splashing of oars, the grinding of rowlocks long before they came in sight, far voices, and even the sharpening of a scythe on shore.
And then a shrill whistle and a train rushing across the meadow-land would remind us that this great quiet of the Thames is within easy reach of London.

2005:  Picture, Doug Myers –

Nuneham Railway Bridge, Doug Myers © 2005
Nuneham Railway Bridge, Doug Myers © 2005

2023:  Bridge collapsing:

Nuneham Railway Bridge, 2023
Nuneham Railway Bridge Cracks

2023: The railway line between Didcot Parkway and Oxford was closed April to June 2023 to enable Network Rail to carry out repairs to the viaduct's southern abutment following failed grout stabilisation.

Nuneham Viaduct was closed for safety reasons on 3 April 2023 after Network Rail monitoring equipment detected increasingly significant movements in the structure, which crosses the River Thames between Culham and Radley.

The viaduct had been monitored since 2018, with extra equipment installed earlier this year. Prior to the recent rapid deterioration of the viaduct, its condition posed no risk to trains or passengers, Network Rail said. The viaduct, like other rail infrastructure, undergoes regular inspections, including with the help of divers every three years. Manual inspections have been carried out at the viaduct every three months since 2021, with full inspections of the stability of the southern abutment in 2019 and 2022. These inspections led to a planned low intrusive ground stabilisation scheme in March 2023.

However, interventions were not successful, resulting in the closure of the line once the condition of the viaduct rapidly and unexpectedly deteriorated. Network Rail’s capital delivery director Stuart Calvert said: "We decided we needed to monitor in more detail how the bridge was moving. But more recently, we've noticed increased movement. So over the last few months, we've put increased monitoring in, and the cracking now is showing how much the bridge has moved in the last few weeks.

And therefore, the solution we had originally was to inject a polymer grout, and we injected that polymer grout into the embankment under the abutment to stabilise movement, but unfortunately it hasn't worked. And because of that the bridge has kept moving, and in the end we were unable to keep the level of the rails where we need it to be to safely run trains.

Commenting on the history of the bridge, Calvert said: "The steel structure was put in place in 1909. The original viaduct across the river was way back in the 1840s, and this is the third reincarnation of the structure.
"What's really interesting is even though the steel structure was from 1909 and the far side is 1929, this abutment here where we've got a problem probably stems from the original bridge. Over many years, this bridge and this abutment have been sinking."

Contractors are now working to replace the southern support structure with a new one, which will provide a long-term fix, with both passenger and freight trains expected to run again between Didcot Parkway and Oxford by Saturday 10 June 2023.

"We can't do a temporary repair on this abutment, we've actually got to replace it. And to do that, we're going to build a temporary structure in the middle of the Thames, so we're going to have to close half the river, and we're going to put in a piled foundation and a temporary trestle so we can support the steel structure and hold that level," Calvert said.