The concept of a landbridge refers to different types of integrated origin-destination international movements of shipments (in various combinations of sea, land and air) under a single waybill. There are different examples of landbridges with different characteristics related to transport supply facilities, organisational structure and managerial skills. Certain limitations of existing landbridge studies are discussed. They include the failure of a comprehensive academic study to account jointly for both demand and supply of landbridge services. Most articles on landbridges discuss the Trans-Siberian Railway or east-west coast landbridges of the United States of America. No comprehensive academic studies of landbridges in general were found. The main features of the research can be summarised as: *A comprehensive review of literature related to landbridges * An investigation and analysis of Iranian transport supply and demand including both domestic and foreign trade. * An investigation and analysis of the demand of the Central Asian and Caucasus countries (Former USSR republics) for transport * The development of a demand and supply model related to an Iranian Sea-landbridge (ISLB) for eight Central Asian and Caucasus countries and Iran. * Evaluation of the impacts of demand on landbridge supply. *A comprehensive review of the scenario approach and its application to the Iranian Sea landbridge study using a regression technique. Three scenarios are developed (optimistic, most probable and pessimistic). The main result of the scenario modelling suggests that the transport system of Iran requires considerable improvement to compete effectively with other landbridges, given an increase in trade from Iran and the Central Asian and Caucasus countries.