【文章內(nèi)容簡介】 d as cluster managers. Revenues of port authorities The port authority has various sources of revenue. The existence and relative importance of various charges differs between ports (Asar, 2021). In general, port authorities generate revenue from three sources: ? charges to shipowners/ ship operators。 ? charges to tenants in the port, including terminal operators。 ? charges to cargoowners. Charges for shipowners/ship operators are termed ‘port dues’ and in most cases related to the size of vessels. These port dues are justified by investments in dredging, safety systems, and investments in port basins. Charges for tenants are lease charges to firms such as terminal operators and warehousing and production firms. Charges for cargo owners are termed wharfage and are mostly related to cargo volume or to the value of goods. Some port authorities do not have wharfage charges, because cargo owners indirectly pay both other charges as well. In such cases, a part of both other charges can be conceived as ‘pseudowharfage’. This implies that the port charges do not have to be fully justified on the basis of investments with benefits for either tenants or shipowners. Investments for the benefit of cargo owners, such as investments in hinterland infrastructure, hinterland access or warehousing facilities, can be justified because the cargo owners as users of the port pay the port charges ‘in the end’. Therefore, investments with benefits for these cargo owners are justified, even if port charges are paid only by tenants and shipping firms. Investment decisions of port authorities The port charges have to be justified by investments of the port authority. ‘Investment appraisal’ –on the basis of which criteria do port authorities decide to invest is therefore a central issue for port authorities. We claim that the following simple rule is a guideline for investment appraisal of port cluster managers: benefits for the cluster of an investment should exceed costs for the cluster. Cluster benefits are the sum of all benefits of firms in the cluster, cluster costs are the costs of an investment for firms in the cluster. In most cases costs are incurred because port charges are required for cluster investments. Since costs equal revenues, a high investment level requires high port charges. 4. Cluster governance in the port of Rotterdam In this section we present an empirical case study of the port of Rotterdam. We interviewed 43 port experts in the port of Rotterdam. First, we deal with the importance of cluster governance for the performance of the cluster. In the next four paragraphs, we discuss the empirical results for the four variables that influence the quality of the cluster governance. Sixth, we briefly discuss the role of the port authority in Rotterdam and end with conclusions. The importance of cluster governance in Rotterdam’s seaport cluster These results show that cluster governance is less important than the structure of the cluster and the economic development in general, but more important than national and international policies. The experts were also asked to indicate the relative importance of the four variables of cluster governance, also by ranking them. Trust in Rotterdam’s port cluster Virtually all cluster experts agree with the proposition that trust is important for the quality of t