19724
During the latter stages of the construction of PLUTO considerable damage was caused to the track on the extension when , to speed up the work , lengths of pipe were dragged along the trackbed by bulldozers , resulting in its reduction to a single track after the war .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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