For Gasunie, NEO performs updates for analyses of the depth location of the Gasunie pipeline network of approximately 14,000 km. At a glance, an overview of situations where the height of the ground level (and thus the depth location of the pipelines) has changed emerges. These updates further enhance the safe location of the pipeline network.
The updates are performed using the Actueel Hoogtebestand Nederland (AHN). The analysis is part of the Safe Location Management process. Other analyses are also part of this process, such as monitoring with helicopter flights and the use of aerial photographs and satellite images to identify changes.
Gasunie: "To ensure safe and reliable gas transport, the undisturbed location of infrastructure is crucial. That means we place high demands on the quality of our data, especially the depth of coverage." The pipeline network has a minimum coverage of 85 cm to prevent a pipeline from being accidentally hit during earthworks. Through the KLIC process, Gasunie is involved in preparations for excavation work by third parties. Follow-up activities make use of data on the actual situation outside. With the AHN, this can be done in an efficient way: after each update of the AHN, the ground level data are updated and, if necessary, verified in the field. This creates a consistent picture of the coverage on all Gasunie pipelines throughout the Netherlands and allows for targeted and economical deployment of people in the field.
The AHN is a very useful source for monitoring ground level elevations. It is a land cover file that provides a consistent picture for with which the coverage of oven all Gasunie pipelines can be inferred. However, AHN does not give elevations below water level. Another point of attention are the zones around watercourses and vegetation where the AHN classification can be suboptimal, e.g. if vegetation in or on the water is classified as ground level. This is because then the ground level is estimated too high. Together with Gasunie, NEO has developed a methodology whereby these situations can be spotted and identified early to avoid overestimating coverage.
Monitoring assets and infrastructure is one of NEO's specialities. Steven Braakman of NEO: "With the latest releases of the AHN, version 5, Gasunie and NEO are again teaming up for a safe living environment."