Please note: The algorithm descriptions in English have been automatically translated. Errors may have been introduced in this process. For the original descriptions, go to the Dutch version of the Algorithm Register.

Crowd monitoring

By understanding crowds, it becomes visible where problems may arise so that involved parties together determine what, when should be done by whom to keep the city safe with large groups of people.

Last change on 2nd of December 2025, at 14:50 (CET) | Publication Standard 1.0
Publication category
Other algorithms
Impact assessment
Field not filled in.
Status
In use

General information

Theme

Public Order and Safety

Begin date

04-2023

Contact information

algoritmeexpert@rotterdam.nl

Link to source registration

https://algoritmeregister.rotterdam.nl/p/Onzealgoritmes/53761720551735699

Responsible use

Goal and impact

PURPOSE: Crowd management is the monitoring of crowds to then support the actions of the various disciplines based on pre-agreed basic points.


IMPACT: Impact on citizens is small; the algorithm plots where crowds are present and how they develop.

Considerations

Keeping users safe in and manageable public spaces is high priority

Human intervention

The crowd monitor is not leading in making a decision. It is an additional tool during events. It is used in the control room, where police, boas and emergency services are coordinated. The crowd monitor supports making better decisions, for example on the deployment locations of enforcers.

Risk management

Field not filled in.

Elaboration on impact assessments

IAMA and DPIA will be launched upon further development and structural deployment.

Operations

Data

Addresses and buildings, Large-scale topography, Share mobility, Traffic information, Parking data, Traffic flows from TomTom, Weather information, Crowd information, Event information

Links to data sources

  • Basic registration of addresses and buildings (BAG)
  • Basic registration of large-scale topography (BGT)
  • Share mobility
  • Traffic information
  • Parking data
  • TomTom traffic
  • Infoplaza weather information
  • Resono pressure information
  • Event information

Technical design

The crowd monitor is a dashboard intended to provide insight into crowds in the city. Insight into crowds shows where problems may arise so that involved parties can decide together what, when should be done by whom to keep safe with large groups of people in the city.


The crowd monitor has map views of how busy the city is at that moment. The map combines various data sources, such as traffic data, ov data (from public sources). In addition, location data were collected from mobile apps. The mobile app data were collected by the supplier, which were delivered anonymously to the municipality. As a result, this data is not traceable within the municipality.


The crowd monitor is not leading in making a decision. It is an additional tool during events. It is used in the control room, where police, boas and emergency services are coordinated. The crowd monitor supports making better decisions, for example on the deployment locations of enforcers.


The dashboard is currently deployed during some events in Rotterdam. In the past, these have been the following events:


- Koningsdag 2023

- Marathon 2024

- Marathon 2025


During Kings Day 2023, a link was made with data from social media. The purpose of this was to assess whether any risks were visible with regard to already developing and potential escalations. This link was later abandoned in the further development of the monitor.

External provider

Argaleo B.V.

Similar algorithm descriptions

  • If something needs to be fixed or cleaned up on the street or in a park, it can be reported to the municipality via Signalen, the open source reporting system of, for and by municipalities.

    Last change on 8th of September 2025, at 9:02 (CET) | Publication Standard 1.0
    Publication category
    Impactful algorithms
    Impact assessment
    Field not filled in.
    Status
    In use
  • To correctly determine when and where sweepers operate in the city, we ensure that relatively little waste is visible in public spaces and contribute to a cleaner city.

    Last change on 31st of October 2025, at 13:37 (CET) | Publication Standard 1.0
    Publication category
    Impactful algorithms
    Impact assessment
    Uthiek, DPIA
    Status
    In use
  • If homes are not declared at standard, a recommendation for a strengthening scenario is automatically created. The scenario depends on the market value of the current house and the cost of structural strengthening or demolition and new construction.

    Last change on 20th of December 2023, at 7:54 (CET) | Publication Standard 1.0
    Publication category
    Impactful algorithms
    Impact assessment
    Field not filled in.
    Status
    In use
  • By correctly determining when and where waste should be collected from containers, we ensure that relatively little waste is visible in public spaces and contribute to a cleaner city.

    Last change on 31st of October 2025, at 13:35 (CET) | Publication Standard 1.0
    Publication category
    Impactful algorithms
    Impact assessment
    Uthiek, DPIA
    Status
    In use
  • The fact that we can better and more specifically monitor good landlordism and compliance with the Housing Act means that offenders (also known as slumlords or property abusers) can receive a fine (if there is an offence) sooner than was previously the case.

    Last change on 12th of July 2024, at 9:51 (CET) | Publication Standard 1.0
    Publication category
    Impactful algorithms
    Impact assessment
    Uthiek, DPIA
    Status
    In use