Recent estimates point out that more than 40% of the World's population is currently living within 100 km of the coast (UN, 2017). As clearly identified by Taveira Pinto et al. (2022), this number will most likely increase in the coming decades, mainly due to the growth of population in large cities (often located in coastal zones), and due to the migrations registered from inland to littoral regions whose larger economic growth offers more opportunities for social and economic empowerment.
This general context sets out rising needs to design new coastal and estuarine infrastructures ultimately responsible to link land based activities to sea, as well as to promote the sustainable interactions between humankind and such locations. In this sense, inputs related to the efficient design of marine structures remain as valuable contributions to a growing demand for optimised design of infrastructure towards sustainable engineering.
The coastal population's growth and its rising density bring along other relevant challenges to maritime engineering, among which shipping services are a practical example. For instance, from 2010 to 2019, both the container fleet and shipping demand have registered consistent growth, with rates varying between 2% to 14% (Sand, 2020). In light of the recent pandemic crisis, and more recently the rising prices of fuel, the expected growing demand for the maritime transport of commodities, products and ultimately people will amplify the need for optimisation of shipping services and shipping management in ports, harbours and other coastal infrastructures, as well as, speed optimisation strategies, recovery strategies from supply disruptions caused by random adverse events, among others.
For more than 20 years Maritime Engineering has provided a considerable number of novel scientific case studies and applied engineering contributions to the many fields encompassed in the topic of ‘connecting the land and to the sea’, including complex marine structures and vessels (Premalatha et al., 2015; Cox and Czlapinski, 2016), ships engineering and marine shipping (Serrano et al., 2018; Camarero et al., 2022). In line with this track-record, the present issue of Maritime Engineering compiles two papers: one on the topic of deck jetty's’ design and another regarding the optimisation of marine shipping.
Following the first issue of 2022 (Bruce, 2022), this second issue starts with a very practical and interesting analysis of a suspended deck jetty presented by Bullock (2022). Although many guidance has been given over decades on the structural modelling of bridge decks, and some on the specific case of exposed jetties, e.g. McConnell et al. (2004), there is a paucity of literature available on the specific topic of suspended deck jetty structures analysed with finite-element methods. In this paper, a review is made on the common deck modelling methods and common construction techniques of orthotropic decks and typical jetty decks in order to provide guidance for the suspended jetty deck cases. Bullock (2022) shows how, similar to other cases of bridge decks engineering, the recent advances in computational resources have contributed to minimise and mitigate the historically reported shortcomings of Finite-Element approaches. Furthermore, this practical analysis has been demonstrated via a benchmark case study, which also compares grillage and finite-element methods. This paper can be quite useful for everyday engineering and design actions taken by professionals dealing with such structures. In addition, Bullock (2022) provides final recommendations to obtain an accurate model representation of a suspended deck jetty, including guidance on the most efficient way to analyse it through finite-element methods.
The connection between land and sea, in broad perspective, is not only made by marine structures such as jetties, but also by the numerous ships and other marine transport and associated infrastructure (e.g. harbours, ports, marinas, etc), that are crucial for the socio-economic activities of modern Society, where about 90% of its goods are transported by sea and where in the past 20 years there was a doubling in the average size of a container ship (World Economic Forum, 2021). In the second paper of this issue, Wen et al. (2022) investigate the dynamic operations recovery polices for liner shipping services, taking into consideration buffer time allocation and other uncertainties. This research focuses on minimising the delays of liner shipping services, which is in turn a contribution towards the reduction of financial consequences and CO2 emissions. Wen et al. (2022) incorporate buffer time allocation operational decisions for the service schedule and dynamic recovery actions to address uncertainties associated with speed, strategy, accelerating handling and port skipping. As a key novelty, this paper proposes multi-objective robust vessel scheduling model to optimise the robustness of liner shipping service, considering a balance between numerous aspects of service, economic and environmental in nature, among others under different uncertainties. The proposed model provides a Pareto-optimal solution, which is obtained by multi-objective grey wolf optimiser and multi-objective genetic algorithm, whose application to liner shipping problems is, to a certain extent, a novelty per-se. Furthermore, the model is proven to outperform the most popular version of the non-dominated sorting genetic algorithm (NSGA-II). The research carried by Wen et al. (2022) may also be applicable to other problems related to harbours and ports management and optimisation.
Given the applicability of Bullock (2022) and We et al. (2022) works, this issue stands a practical contribution to scope covered by Maritime Engineering, in particular when it comes to provide added value to the fields of marine structures and shipping services, which remain as vital components of humankind's connection to the sea.
