When car weight and equidistance are remarkable, also in comparison with the rated rope tension, the internal rope tensions may be affected by the geometrical position of the cars present on the spans. In practice, during car running along the line, the internal rope tension changes, thus, also the plant absorbed power changes as a consequence; this phenomenon, known as "rope tension surging" may result particularly irritating and, also, induce resonance when several cars pass on towers at the same time; in such cases, span load conditions change in a very short time (a few seconds) from laden span into empty span, and, the motor turns out to be no longer capable of reacting promptly, thus giving rise to quick speed changes and span swinging as a consequence. It is, therefore, required to check that the above circumstances do not occur. This may be carried out by analysing the periodic function which describes the behaviour of tensions as a function of load positions; the program provides the relevant diagrams, and, in the future versions, also the opportunity to analyse this function through Fourier formula.

The program, first displays the Table below, showing the test hypotheses taken into consideration. Click twice on the concerned hypothesis:

The table showing the rope tension numerical values is as follows: