How to create safety for pleasure boats in Fehmarnbelt?

In my latest blog post I showed you an intensity plot and a movie of the large commercial ships sailing in and out of the Baltic Sea through Fehmarnbelt.

But when building a tunnel across Fehmarnbelt it is also important to have knowledge about the intensity of movements with smaller local ships, such as pleasure boats, local fishing ships and the like.

The safety of these ships is equally important. Persons in a pleasure boat are vulnerable in collisions with construction vessels or large commercial ships and therefore a pleasure boat crossing Fehmarnbelt will draw much attention from construction vessels and the large commercial ships. When we know the intensity and sailing
pattern of the smaller local ships, we can plan how to handle this issue and introduce the necessary risk reducing measures for all vessels in Fehmarnbelt.

How to get that information?

So, how do we get the information we need? Luckily a radar is there is installed at the top of a silo in Rødbyhavn (Rødby Habour), and by using those data we were able to get an overview of the smaller local ships.

First we had to seek out and remove all the tracks from the larger commercial ships (also seen in AIS data – a GPS based system for tracking of ships).

We did that by creating an algorithm to match the tracks in radar with the tracks seen in AIS. As you see in the picture, the problem with matching data from the two data sets was that they were registered at almost the same  spot at almost the same time.



Well, we solved the problem and were able to remove the international commercial traffic from the radar data and were left with illustrations of movements from smaller local ships, such as pleasure boats, local fishing ships and the like.

As you can see, the local traffic with smaller ships has quite another pattern than the international commercial traffic that I showed in my last blog post, and a significant seasonal variation: on top you see around 400 tracks in January, on the buttom you see around 1800 tracks in July.

How to get an overview of the traffic in Fehmarn Belt?

My name is Finn Mølsted Rasmussen. I am 43 years old and Senior Project Manager in Ramboll’s department for Risk and Safety. This is my first contribution to the blog as a guest blogger.

In my department we have been working with navigational safety for ships passing through Fehmarnbelt during construction and operation of the Fehmarnbelt Fixed Link since 2006. Since 2009, I have been Project Manager for a team of five dedicated colleagues.

I will guest this blog from time to time and write about my work with navigational safety.

Knowledge about ship traffic is important since it comprise the basis for conducting all other analyses to find the right solution to maintaining navigational safety during construction and operation of the Fehmarnbelt Fixed Link. Both Danish and German authorities are naturally focused on having a safe and unhindered passage for commercial traffic through Fehmarnbelt, as this is the primary corridor for ships entering or leaving the Baltic Sea.

One of the worlds’ busiest ship traffic corridors

With more than 80.000 movements per year, Fehmarnbelt is one of the worlds’ most busy ship traffic corridors: about 40.000 movements alone from commercial ships passing through Fehmarnbelt on their way to and from the Baltic Sea (the largest of which is almost 400m long). There are around 35.000 movements from the Rødby-Puttgarden ferries and around 6.000 tracks from fishing vessels, pleasure crafts and other local traffic.

Radar data – the most important data sources

In our studies, we use AIS data (a GPS based system for tracking of ships) and radar data (from a radar in Rødby) as the most important data sources.

Thanks to these data sources, we can perform extensive studies of the existing ship traffic in the Fehmarnbelt. The work started in 2006 and is on-going to continuously improve our knowledge about the ship traffic in the area.

What do we analyse?

The analyses cover simple counts of ship traffic volume and characteristics such as length, ship type, speed, draught, use of pilot, variation in traffic intensity over time, frequency of visits from different ships, destination of ships, number of overtakes close to the Fehmarnbelt Fixed Link alignment, accident registrations etc.

The analyses also cover more complex analyses of the ship traffic pattern such as movies and intensity plots that analyses the distribution of ship traffic transverse to the sailing routes. Also, we do interesting analysis of radar data to find ship tracks from smaller ships seen in radar data but not seen in AIS data.

When overlaying the ship tracks for longer periods of time (typically one year) we get intensity plots (see photo in top) that can tell us about the main sailing routes in the area and their extension and amount of traffic.

In my next blog post I will write more about our work with navigational safety.