Several studies have been carried out until now by various Research Agencies and Railway Administrations to quantify the effects of the track-bed geometrical characteristics on the transverse strength of the track. Unfortunately, not all the possible scenarios in terms of track components, track-bed cross profile, operating conditions etc. have been investigated and not all the relevant variables have been directly measured. Therefore data available from the literature have different degrees of reliability. With the aim of completing the knowledge on the track stability and covering the totality of the possible relevant scenarios, an experimental research program is being developed in the framework of a cooperation between RFI, Italcertifer and DiME. In order to perform the investigation under quite general conditions and to reduce the experimentation costs, n. 26 significant scenarios have been identified and reproduced on as many independent track segments. By applying on each track segment a transversal load, the strength of the ballast-sleeper interface has been determined. The results relative to the first eight scenarios are presented by means of lateral track displacement vs. applied load diagrams and more synthetic numerical tables.