Empirical differences between time mean speed and space mean speed

VL Knoop, SP Hoogendoorn, HJ van Zuylen

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientific

28 Citations (Scopus)
31 Downloads (Pure)


Insight into traffic flow characteristics is often gained using local measurements. To determine macroscopic flow characteristics, time aggregation of microscopic information is required.

Usually, a data collection system stores values averaged over time. However, it is well known that a time mean average overestimates the influence of faster vehicles, and consequently overestimates the mean speed. As a direct result, densities, computed from flow and speed, are underestimated.

This paper compares the time mean speed and space mean speed, using data of individual car passages on a motorway road stretch. We show that the differences between time mean and space mean averages are substantial, up to a factor four. In particular in the lower speed regions the error is big. We indicate the considerable consequences for the jam density and shock wave speed. Finally, a fundamental diagram based on correctly averaged microscopic data can be fitted much better.
Original languageEnglish
Title of host publicationTraffic and granular flow 2007
EditorsC Appert-Rolland, F Chevoir, P Gondret, S Lassarre, JP Lebacque, M Schreckenberg
Place of PublicationHeidelberg
Number of pages6
ISBN (Print)978-3-540-77073-2
Publication statusPublished - 2009
EventTraffic and Granular Flow '07, Orsay, France - Heidelberg
Duration: 20 Jun 200722 Jun 2007

Publication series



ConferenceTraffic and Granular Flow '07, Orsay, France


  • Conf.proc. > 3 pag


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