As a consequence of the problems of sustainability caused by the growth of road transport, short sea shipping (SSS) has attracted much attention from the European Union in recent years. Road hauliers, as clients of shipping companies, constitute a key player in the development of SSS. For these firms, the use of this transport mode implies a change to their traditional all-road transport operations. Consequently, if these firms want to maintain stable operations in the SSS context, they need to face the challenge of modifying their profile and adopt an appropriate organisational structure. The aim of this article is twofold: first, to analyse, in the context of roll on-roll off SSS, the two possible operating strategies for road transport firms: accompanied versus unaccompanied transport, in an attempt to determine their characteristics and the factors that condition their use; and second, to analyse the challenges facing international hauliers by changing the process from the all-road transport option to the use of unaccompanied transport in SSS operations, and how these challenges are addressed. A study is made of five international road hauliers that have adapted to become intermodal transport operators. Our findings reveal five key areas for change: organisation of haulage and fleet restructuring, restructuring of driving staff, changes in the operating model and development of coordination capabilities, improving the commercial capacity at destination, and establishing an adequate infrastructure to organise haulage in the destination country. Proper management of the adjustment process largely determines the success of road hauliers in the use of unaccompanied SSS.