Indian politicians and historians claim that the Taj Mahal could collapse within five years if work to repair the structure’s timber foundations is not carried out.
“Will cave in two to five years”
Cracks in the tomb and four minarets, as well as subsidence, were first recorded last year, according to Agra MP Ramshankar Katheria.
“If the crisis is not tackled on a war-footing, the Taj Mahal will cave in between two and five years,” claimed Ramshanker.
The mausoleum, which attracts 4M visitors a year, was built in 1631 and is supported on mahogany posts. According to Ramshanker and a team of historians, the foundations are believed to have been drying out and rotting over many years but the low water levels in the adjacent Yamuna River this summer have accelerated the problem.
Water table problem
Arup associate director Andrew Lawrence, a timber specialist said the Taj Mahal’s foundations could be at risk if the drop in river levels is a long term issue. “The principle of the timber pile is that it is installed below the water table in an anaerobic environment, so the pile doesn’t rot,” he said.
In terms of rate of decay, Lawrence said that, in general, if the timber pile had a reasonable diameter then as the water level falls, some evidence of decay might be seen within months but to lose significant structural section could take perhaps two to five years.
“However, if the decay was due to termite attack of the exposed pile heads, then the impact would be seen much more quickly,” he said.
Many historic buildings are built on timber piles and Lawrence said that as long as the piles stay below water level, the piles should last forever.
“But if the water level drops and the piles are no longer fully submerged, then there will be problems after a few years,” he said.
The use of mahogany piles for the Taj Mahal seems unusual, according to Lawrence, as the material would likely have had to have been shipped from Africa.
“Although mahogany is a hardwood, it is only moderately durable against rot”
Arup associate director Andrew Lawrence
“Softwood is more common for timber piles − for example much of Venice is built on softwood piles,” he said. “Although mahogany is a hardwood, it is only moderately durable against rot − similar to larch or Douglas fir − and not as good as some other hardwoods such as teak.”
Lawrence explained that remedial solutions would depend on how advanced the problem is.
“At the Tobacco Dock in London, soakaways were used to recharge the water table to ensure the piles remained below water level,” he said.
“If the problem at the Taj Mahal is not too far progressed, then one solution could be to install a cut-off wall around the site and to locally raise the water table.
This would be minimally invasive to the structure itself.”
Nonetheless, Lawrence warned that if evidence of settlement has already been seen in the structure then a cut-off wall would only prevent the problem advancing.