Traffic jam severity

  • Kilometre hours of traffic jams in December 2020 66% lower than in December 2019

    In December 2020, the traffic jam severity on the main roads in the Flemish Region was on average 248 kilometre hours per working day. In December 2019, that number stood at 733 kilometre hours. This corresponds to a decrease of 66%. This decrease is strongly linked to the preventive measures that were put in place from mid-March 2020 on as part of the Covid-19 crisis.

  • 337 kilometre hours of traffic jams per working day

    In December 2020, the annual average of the traffic jam severity on the main roads in the Flemish Region was 377 kilometre hours per working day. This means that in the previous 12 months (January 2020- December 2020) there was an average of 377 kilometres of traffic jams every working day for one hour.

    Traffic jam severity rose in recent years, with a peak in May 2018. In the period that followed, there was slight decrease in the annual average of the traffic jam severity, followed by a very sharp decrease in 2020. In December 2020 traffic jam severity was at its lowest since the beginning of observations.

  • Especially traffic jams in the regions of Antwerp and Brussels

    The longest and the highest number of traffic jams occur in the Antwerp and Brussels regions. In the Antwerp region, traffic jam severity rose faster than in and around Brussels until the beginning of 2020. The Ghent region and the rest of Flanders are confronted with much fewer traffic jams on the main roads.

    The strong decrease in traffic jams in 2020 was more pronounced in the Antwerp and Brussels regions than elsewhere.


Mobility and Public Works data room: New method of calculating traffic jam severity 
Flemish Traffic Centre: Traffic indicators


Traffic jam severity: indicates the average scale of the traffic jams on a certain collection of roads. The indicator combines traffic jam length and traffic jam duration and is expressed in kilometre hours.
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.

Publication date

15 February 2021

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