The 175-year-old mystery of the railroad workers may now be solved after a team led by brothers Dr William and Frank Watson, using thermal imaging and ground-penetrating equipment, disturbed a 40ft by 20ft area which, they say, may contain the 57 bodies.

The labourers arrived in Pennsylvania in June 1832 to construct the Philadelphia and Columbia Railroad but six weeks later all had died and were buried without ceremony in a ditch.

While the popular consensus is that the men perished in a cholera epidemic, there are also theories that they were murdered by anti-Irish vigilantes.

The year before, such feelings had sparked rioting in Philadelphia.

Excavations will now take place over the coming days to see if the men's final resting place has indeed been discovered - and Frank Watson has revealed that a local cemetery has offered to give the bodies a proper burial.

Speaking on radio today, he added that advances in thermal imaging technology had enabled the team to make further progress in the painstaking search.

"We have uncovered what we think is the site of this grave," he said.

"This is an enormously important breakthrough and we have an image of these poor men in their final repose.

"We have all the necessary permits for exhumation and to place them in properly consecrated ground and West Laurel Hill cemetery nearby agreed to take the remains and bury them properly."

Dr Watson inherited the legend from his grandfather, who was a railroad employee who compiled a list of files on the case.

"We now believe we are inches away from finding this grave and we are just itching for the rain to stop on the East Coast."

The grave may also be declared a crime scene by police if the remains are discovered to have died through violence.

Local man Brian Hegarty said today he believes that his relative may be one of those buried at Duffy's Cut.