Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022;49(2):445-466.
doi: 10.1007/s11116-021-10182-8. Epub 2021 Feb 26.

The changing accuracy of traffic forecasts

Jawad Mahmud Hoque  1 , Gregory D Erhardt  1 , David Schmitt  2 , Mei Chen  1 , Ankita Chaudhary  2 , Martin Wachs  3 , Reginald R Souleyrette  1
Affiliations

The changing accuracy of traffic forecasts

Jawad Mahmud Hoque et al. Transportation (Amst). 2022.

Abstract

Researchers have improved travel demand forecasting methods in recent decades but invested relatively little to understand their accuracy. A major barrier has been the lack of necessary data. We compiled the largest known database of traffic forecast accuracy, composed of forecast traffic, post-opening counts and project attributes for 1291 road projects in the United States and Europe. We compared measured versus forecast traffic and identified the factors associated with accuracy. We found measured traffic is on average 6% lower than forecast volumes, with a mean absolute deviation of 17% from the forecast. Higher volume roads, higher functional classes, shorter time spans, and the use of travel models all improved accuracy. Unemployment rates also affected accuracy-traffic would be 1% greater than forecast on average, rather than 6% lower, if we adjust for higher unemployment during the post-recession years (2008 to 2014). Forecast accuracy was not consistent over time: more recent forecasts were more accurate, and the mean deviation changed direction. Traffic on projects that opened from the 1980s through early 2000s was higher on average than forecast, while traffic on more recent projects was lower on average than forecast. This research provides insight into the degree of confidence that planners and policy makers can expect from traffic forecasts and suggests that we should view forecasts as a range of possible outcomes rather than a single expected outcome.

Supplementary information: The online version contains supplementary material available at 10.1007/s11116-021-10182-8.

Keywords: Forecast accuracy; Induced demand; Traffic forecasting; Travel demand modeling.

PubMed Disclaimer

Conflict of interest statement

Conflict of interestThe authors declare no conflicts of interest.

Figures

Fig. 1
Fig. 1
Accuracy and uncertainty terminology (Collaboration for Nondestructive Testing n.d.)
Fig. 2
Fig. 2
Distribution of percent difference from forecast (Erhardt et al. 2020)
Fig. 3
Fig. 3
Absolute percent difference from forecast as a function of forecast volume
Fig. 4
Fig. 4
Distribution of percent difference from forecast adjusting for great recession
Fig. 5
Fig. 5
Trend in percent difference from forecast, excluding resurfacing projects
See this image and copyright information in PMC

References

    1. Anam S, Miller JS, Amanin JW. Managing traffic forecast uncertainty. ASCE-ASME J. Risk Uncertain. Eng. Syst. Part A Civil Eng. 2020;6(2):04020009. doi: 10.1061/AJRUA6.0001051. - DOI
    1. Antoniou C, Psarianos B, Brilon W. Induced traffic prediction inaccuracies as a source of traffic forecasting failure. Transp. Lett. 2011;3(4):253–264. doi: 10.3328/TL.2011.03.04.253-264. - DOI
    1. Bain R. Error and optimism bias in toll road traffic forecasts. Transportation. 2009;36(5):469–482. doi: 10.1007/s11116-009-9199-7. - DOI
    1. Bain, R., Polakovic, L.: Traffic Forecasting Risk Study Update 2005: Through Ramp-up and Beyond. Standard & Poor’s, London. http://toolkit.pppinindia.com/pdf/standard-poors.pdf (2005). Accessed 06 Oct 2016
    1. Bastian A, Börjesson M, Eliasson J. Explaining ‘peak car’ with economic variables. Transp. Res. Part A Policy Pract. 2016;88(June):236–250. doi: 10.1016/j.tra.2016.04.005. - DOI

LinkOut - more resources