I travelled over the old Severn rail bridge in about 1956 or 7. The cost of repairing it after it was damaged in 1960, following an underwater survey which found extensive damage to Pier 16, was estimated at £312,000, against dismantling costs of £250,000. BR planned to go ahead with reconstruction but just before the work was due to start, a capsized tanker caused further damage to Pier 20, and this pier was struck again when a contractor's crane broke adrift. These accidents added a further £20,000 to the estimated costs of repair, and in 1965, British Rail decided that the bridge was damaged beyond economic repair and opted for demolition.
Figures quoted are from Wikipedia. We'll never know what the actual rebuilding costs would have been but that's all water under the bridge now!
This has been a proposal since the bridge was dismantled. It was proposed the repaired bridge be made dual for road and rail use from 1961 by traffic lights as it was only single track width. This was before the first road bridge was started.
Strain gauges had been fitted in 1959 and tested by two Castles coupled together with success to allow heavier locos than Panniers for Winter weekend diversions when Severn Tunnel was closed for maintenance. Up until then, only 3-car Swindon Cross Country DMUs could be used.
I always understood the repair costs were £300,000 and the demolition costs were £350,000 not £250,000. These were the figures talked about locally at the time. Locals couldn't believe the more expensive option was taken.
I lived close to Severn Bridge in 1960 and was able to see the flames of burning petrol on water that night and hear the screams of the seamen in the water burning to death and not being able to help them.
Pier 20 was the one hit by the barges dislodging two spans either side. I didn't know pier 16 was damaged also in the accident. I did know that it was to be repaired and locally a large single span was constructed at Fairfield shipyard on the west bank of the River Wye at Chepstow to replace two spans that were lost. The intension was to float the span upstream and lift into position.
The twice daily service via Gloucester for secondary school children from Sharpness to Lydney ceased in 1962.
In the end, it was decided to demolish in about 1966. This was much harder than expected when it came to removing the piers and they had to be dynamited.
Because of the difficulty, the cost of removing was about £70,000 (about £1.2m at to-days prices) more than the cost of repair including fabrication of the replacement span. The span languished on site in Chepstow for many years.
The people of Lydney and Sharpness/Berkeley were separated after being linked for nearly 100 years and it was a big wrench as there was no public transport alternative. There wasn't even a formal closure process. I used it a lot. Lydney Town to Berkeley Road via the bridge at 10d return was cheaper for a school boy than 1/2d return Lydney Junction to Gloucester for train spotting. I would be all in favour of another bridge in this position for joining the two sides of the river but at what cost?
The formation is still intact on both sides apart from where Lydney bypass uses the trackbed between Nass Crossing and Lydney Junction station.
As an aside, my great grandfather worked on building the bridge and my uncle was involved in demolition. As a result I have a handed down original set of engineering plans dating from 1870 with all the measurements and an original watercolour of the finished bridge painted from upstream to show to shareholders what it would be like before they committed to invest.
The design engineers were from Lydney, consulting engineers from Westminster and the construction engineers were from Liverpool.