Ships continually communicate their position and receive regular updates on any information relevant to their course. They do this using the Automatic Identification System (AIS). In the past, however, this system had trouble processing large numbers of signals simultaneously, leading to unreliable performance. To remedy this, Rijkswaterstaat asked TNO for help. In the end, their collaboration produced a smart algorithm and the AIS Slotplan Solution. Thanks to this planning tool, waterway managers always have a clear picture of shipping traffic on inland waterways.
Say there’s a thick mist hanging over a river in the Netherlands. In situations like these, barge crews will use their radars to see which ships are in their immediate vicinity. But radar has its limitations: it can’t penetrate dykes or buildings along the shore. This means that on-board radars will sometimes ‘overlook’ large vessels just around a river bend. Not exactly inessential information, some might say. It’s in situations such as these that AIS offers a much-needed solution by offering a complete picture of shipping traffic in the area, including ships that wouldn’t show up on radar screens.
AIS is the system that ensures that vessels identify themselves and transmit their position automatically. This leaves barge crews free to focus on other tasks. Initially, AIS was only used for maritime shipping, but the inland-shipping industry soon saw the benefits of the system, too.
“There are several good reasons to track inland shipping traffic in real time. Chief among them would be its usefulness to shipping-traffic management”
Smaller chance of accidents
Of course, barge crews aren’t the only ones who can benefit from AIS: the system can also be of great use to waterway managers. When ships get into trouble, for instance, waterway managers want to arrive on the scene as quickly as possible to provide help. With AIS, this becomes much easier. But there are several other good reasons to track inland shipping traffic in real time. Chief among them would be its usefulness to shipping-traffic management. Another reason would be to keep ships up-to-date on current waterway information, such as accident sites or the location of a stranded or sunken vessel. All these things combined lead to a vastly improved level of service and a smaller chance of accidents.
Limited transmission capacity
Since 2012, Rijkswaterstaat, the Coastguard, the Port of Rotterdam Authority, the Port of Amsterdam and the Scheldt Radar Chain have been mapping the positions of inland vessels and transmitting current information to ships. To facilitate this, AIS base stations were installed along all Dutch waterways. But the antennas on these stations only have limited transmission capacity. When several waterway managers transmit at the same frequency simultaneously, messages can sometimes get lost in the noise.
A game of chess
“It’s practically impossible for waterway managers themselves to regulate who can transmit and when, as there are too many factors at play. In a way, it’s like a game of chess,” Pieter Venemans says. Over the past three years, in his capacity as senior scientist and consultant at TNO, he regularly sat down with waterway managers. The goal of these talks was to find a way of making sure that shoreside AIS stations would no longer transmit multiple signals at the same time.
“We created an algorithm that accurately calculates the reach of different AIS signals and calculates which waterway managers can use which antennas at any given moment”
Going out on the water
“At TNO, we developed an AIS Slotplan Solution,” Venemans continues. “This entailed creating an algorithm that accurately calculates the reach (in km) of different AIS signals and it calculates which waterway managers can use which antennas at any given moment. But to ensure we were being as meticulous as possible, we first had to get a clear picture of where all the AIS antennas are and what their reach is. Out on the open sea, you know exactly how far radio waves will travel; on land, it’s an entirely different story, with hills and tall buildings blocking your signal. And because there are more transmitters in a much smaller area on land compared to at sea, there’s an increased risk of interference. That’s why a number of my colleagues spent months on a ship measuring all kinds of frequencies along the inland waterways.”
Sitting down with all parties involved
The project also provided a great opportunity to bring together a number of waterway managers. These included the project’s client, Rijkswaterstaat, as well as the Coastguard, the Port of Rotterdam Authority, the Port of Amsterdam and the Scheldt Radar Chain, all of which must work closely together to ensure AIS functions properly. “These waterway managers had never had regular meetings before. And even though the goal of the meetings was to develop the AIS Slotplan Solution, they also regularly took advantage of the situation to discuss other subjects,” Venemans says. “They would talk about problems they were dealing with and share solutions. So they were able to help each other on several levels, which was nice to see.”
The result? A well-functioning AIS that continuously tracks all ships with a transponder, as well as one that allows waterway managers to provide ships with all the necessary information in a reliable manner. “We’ve also created an online tool with which they can calculate what the consequences will be if they extend or modify their network,” Venemans adds. “They can then share that information with each other and proceed from there.”
“Thanks to the algorithm, the antennas now even have excess capacity”
Exchanging additional information
“And that’s not all,” he continues. “Thanks to the algorithm, the antennas now even have excess capacity. So the waterway authorities can now also use the system to exchange additional information with ships. Still, there is a limit to how much information AIS can process, as the system relies on radio frequencies, which are scarce. It’s not an Internet of Things. And, at the end of the day, AIS is of course expressly intended to monitor shipping traffic and improve safety,” Venemans concludes. “It’s fun to explore other applications, but they will always be secondary.”
A new challenge
Meanwhile, waterway managers are so satisfied with how accurately the algorithm is able to calculate the range of radio signals that they are now considering using it for other purposes as well. To improve the marine VHF radio network, for example.
Would you like to know more?
Want to learn more about TNO’s AIS Solution? Or are you working on a similar project and looking for an organization that can bring different parties together in addition to taking care of the technical realization? If so, please contact TNO’s Jean-Louis Roso.