3rd site exercise at Knottingley using P.B.I. 10-11 October 1981 (IM-TD-025)

This site exercise was a continuation in a westerly direction of the 2nd site exercise at Knottingley on the 26/27 Sept 81 (SMSN 579, P G S Carlin). At the start of the exercise the first sleepers were injected with 0.75 kg of stone, and this was gradually increased...