Photos show 'more drilling' needed to fix Sheffield Supertram sinkhole - which could be bigger than Nelson's Column
“Further drilling is now taking place to establish the shaft's depth”
More drilling is needed before a shaft - which could be bigger than Nelson’s Column - under Supertram tracks can be repaired.
Engineers say the upper part of the hole under the line at Birley Lane is in “good condition.”
But an obstruction has prevented them confirming its full depth, which records suggest could be 180ft.
London monument Nelson’s Column stands proud at just over 169 ft from the bottom of the pedestal to the tip of Nelson’s hat.
Further drilling is necessary before a supporting structure can be built and services can re-start, according to South Yorkshire Mayoral Combined Authority which owns Supertram.
The blue line has been closed for more than two months after the shaft was discovered on August 23.
In an update, SYMCA confirmed there was no reopening date.
The closure affects 11 tram stops used by thousands of shoppers and commuters.
Traders at Crystal Peaks shopping centre say they fear for the future due to a drop in trade, which is set to continue throughout Christmas.
A SYMCA spokesperson said: “Checks show the upper part of the shaft is in good condition. However, an obstruction deeper underground has prevented engineers from confirming its full depth, which records suggest could be up to 55 metres.
“Further drilling is now taking place to establish the shaft's depth and understand the surrounding ground, including confirming the depth and condition of the coal seams and underground water levels.
“This information is essential to determining the safest and most effective way of infilling the shaft, while ensuring any work does not affect underground water flows.
“Alongside this, ecological surveys and other preparatory work are continuing so construction can begin as soon as the detailed underground investigations are complete and designs approved.”
Replacement buses are running between Gleadless Townend and Halfway.