Traffic jam severity


Flemish Traffic Centre (via dataroom Department of Mobility and Public Works)


Traffic jam severity: indicates the average scale (on an average working day) of the traffic jams on a certain collection (group) of road segments.

  • The traffic jam severity is equal to the product of the length and duration of the traffic jam, cumulated over the different phases of the traffic jam (cf. the length of the traffic jam evolves over time).
  • Traffic jam severity is expressed in kilometre hours (km x hours).
  • Adding up the traffic jam severity across all the traffic jams on a specific group of road segments, such as an area, establishes the total traffic jam severity for this area.
  • The traffic jam severity indicator only factors in the duration and length of the traffic jams, not the speed of the vehicles in the traffic jams, nor the number of vehicles involved.

The figures reported concern a progressive daily average over the past 12 months (progressive annual average), and refer only to working days (Mondays to Fridays, excluding public holidays).

Kilometre hours: unit of measure used for the traffic jam severity indicator. 100 kilometre hours is the equivalent of a 100-kilometre traffic jam for 1 hour or a 200-kilometre traffic jam for half an hour.

Remarks on quality

The data is based on:

  • Traffic counting loops, traffic counting cameras, automatic incident detection cameras, floating car data and additional reports (by police, road users, etc.).
  • Traffic jam notifications communicated as traffic information by the control room of the Flemish Traffic Centre: in turn, these notifications are generated on the basis of a mix of automatic and manual sources (detection loops, camera images, road police, road users, etc.).

The figures are available for the whole Flemish Region, for the impact areas around the major cities or by road. In all cases, they pertain only to traffic jams on motorways.

The figures reported here relate to the region and the approach roads to Antwerp, Brussels and Ghent and to the other motorways in Flanders.

Due to a new calculation method, these figures differ from those set out in the 'Traffic indicators for the Main Road Network in Flanders’ reports (editions 2010 through 2014). From the 2015 edition, the new method has also been used in these reports.

The figures reported here (based on the new calculation method) are available from April 2012 onwards.

The figures for the 2007 to 2014 timeframe (using the old calculation method) are still available at the open data platform.


Flemish Traffic Centre: Traffic indicators


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