Predicting scour beneath subsea pipelines from existing small free span depths under steady currents

•New equation for predicting current-induced scour beneath a pipeline in areas with existing small free span depths.•Field survey data reveal a significant occurrence of spans with small maximum span depths, supporting the need to predict whether scour will occur under such circumstances.•The conventionally studied shear stress amplification factor decreases nonlinearly with incoming current velocity, which does not accurately reflect the occurrence of scour and thus it is not an appropriate tool for scour prediction.•Scour is expected to occur beneath the TGP based on the high flow velocities recorded in the field and the maximum bed shear stresses computed via CFD at full-scale.