The assessment of liquefaction susceptibility from field tests is conventionally based on the Factor of Safety (FSliq) against liquefaction, relating the Cyclic Resistance Ratio (CRR) with the Cyclic Stress Ratio (CSR). The calculation of CSR is relatively straightforward, whereas CRR strongly depends on the in situ technique from which it is derived. Distinct approaches have been proposed based on quantitative liquefaction risk indexes, namely the Liquefaction Potential Index (LPI) and the Liquefaction Severity Number (LSN). In Portugal, a pilot site for liquefaction assessment has been set up in the Lower Tagus Valley, near Lisbon, within the European H2020 LIQUEFACT project. In this paper, the geotechnical field data from SPT and CPTu is integrated in the three approaches to liquefaction assessment. A comparative analysis of the results is presented and discussed, highlighting the differences and limitations of these in situ tests in the assessment of liquefaction susceptibility in loose granular soils.