City of Diemen: infrastructure maintenance using satellite imagery

The city

Diemen is a municipality in the Netherlands with a population of around 24 000 inhabitants. The city is located in the province of North Holland, east of Amsterdam, within the capital’s metropolitan area. The Diemen Department of Infrastructure has a yearly budget of about four million Euros for maintenance of roads, sewers, and other infrastructure.

The challenge

The city of Diemen is built on soft soil, which means it can sink up to two cm per year. Subsidence rates however vary substantially between neighbourhoods, due to variations in soil composition. Over time, differences in subsidence can cause serious damage to infrastructure. It is therefore necessary to rebuild and elevate roads and sewer systems periodically as a prevention measure. The preventive maintenance cycles are usually planned based on visual inspection and experience of individual inspectors. Visual inspection is neither precise, nor does it offer complete coverage. As a result, in many cases maintenance work is performed either unnecessarily early or too late.

The satellite solution

The city of Diemen ordered a city-wide deformation map from Hansje Brinker B.V., a service provider specialised in infrastructure monitoring. Based on deformation information derived from ASAR (Advanced Synthetic Aperture Radar) satellite data captured from 1992 to 2010, the Department of Infrastructure can determine how quick infrastructure is sinking in Diemen with millimetre accuracy. The deformation map allows practitioners to accurately identify damage and therefore correctly prioritise maintenance activities.

The result

The deformation map enables the city to accurately calculate maintenance cycles at every level (streets, neighbourhoods and districts). In addition, it shows the dynamics of the subsidence measured at each location, so the city can better prevent possible sewer emergencies. The deformation map also indicates that maintenance can be safely postponed in many neighbourhoods, leading to a reduction of the inconvenience and associated costs of construction works. Thanks to the accurate mapping of subsidence, the City of Diemen is capable to provide a more efficient planning of road and sewer maintenance, while providing a better service to citizens.

 “The City of Diemen provides a more efficient planning of maintenance of roads and sewers.” Ron Kaptijn, City of Diemen.