picoseconds and conductivity of 5 sm 1 the seabed mud had a relative permittivity of 10 and conductivity of 2 5 sm u2212 1 fig4 a shows a second embodiment of the present invention where the electromagnetic signal is applied locally within the waveguide formed by the cut itself in fig4 a the pipeline 40 has an inner casing surface 42 and an outer casing surface 44 the signal is applied locally from a rotatable telescopic arm 46 of a suitable pipeline vehicle 48 to close to the cutting head not shown in fig4 typically at less than 1 m preferably less than 0 5 m therefrom in order to improve the accuracy of the cut length measure and the reliability of the through cut detection in fig4 a and b the signal is applied from at least two electrical contacts 50 around the vehicle 48 and located on both sides of the cutting head above and below which generates an electromagnetic wave radiating through the cut not shown in fig4 to radiate out between the contact points and to reflect off the outer casing surface 44 preferably these electrical contacts are arranged on the vehicle 48 itself optionally with tangential distribution both two electrical contacts 50 could be connected to an electrical volt generator which can provide one or more nanosecond voltage pulses as an electromagnetic signal using tdr and to a network analyser which can be used to interpret the received signals to test.