Short Sea Shipping

TML investigated the emissions of Short Sea Shipping compared to road transport, collecting accurate data from several parallel routes in collaboration with transporters and shipowners. The aim was to provide scientific evidence to promote SSS as an alternative mode of transport.


Short Sea Shipping (SSS) stands for transporting goods or people by sea without crossing oceans. SSS is heavily promoted for long distances by both national and international governments as an alternative to road transport. To get scientific support for this promotion, TML investigated the difference in emissions between these two transport modes. Together with some transporters and shipowners, data was collected for several parallel routes. Using this detailed data, TML calculated the emissions very accurately, allowing a fair comparison. The results were presented at a press conference to the Flemish prime minister.

The study showed that there is no clear winner in this comparative study. SSS scores better than road traffic on CO₂ emissions, but scores less well on NOx, SO2, and PM emissions. CO₂ has an impact on climate change; this is a global problem. NOx, SO2, and PM have an impact on regional air quality. Stringent emissions regulations in recent years have made road traffic remarkably more environmentally friendly. A similar wave of environmental regulation did not occur for shipping, so shipping currently scores worse for most pollutants. Recently, however, new policy measures are being taken to reduce shipping emissions.

An update took place in 2016. We used the same methodology for two new trajectories. There is (again) no clear winner in this comparative study: SSS scores better than road traffic in terms of CO₂ emissions, similar in terms of NOx and PM emissions and worse in terms of SO2 emissions. Both modes show an improvement in 2016 as compared to 2008. The improvement in SSS is noticeably greater than road traffic, with spectacular improvements for SO2 (up to factor 20 better), PM (up to factor 10 better), and for NOx (factor 3-4 better).
The conclusion of the 2008 study is hereby confirmed: SSS had a lot of catching up to do in terms of environmental performance. From this study, we can conclude that SSS has indeed achieved this catch-up.
Both the European Commission and IMO have been working on environmental regulations. If the trend of improving environmental performance in shipping continues, it can be expected that SSS will win this race in the future.