Right after the Christmas holiday, I flew to Washington D.C. for the 103rd Transportation Research Board (TRB) Annual Meeting held from January 7-11, 2024. This conference marked a significant milestone in my Marie Skłodowska-Curie Postdoctoral Fellowship, as I presented the first results of my research through a paper titled: “Analyzing the reporting error of public transport trips in the Danish national travel survey using smart card data” and co-authored with Filipe Rodrigues, Maya Abou-Zeid, and Francisco Camara Pereira.
The paper investigates the accuracy of self-reported public transport trips in the Danish National Travel Survey (TU) by comparing this data with the Danish Smart Card system (Rejsekort). The study focuses on identifying and quantifying time reporting errors by matching data from the TU survey with Rejsekort data over a five-year period, from 2018 to 2022.
In our analysis, we successfully matched approximately 70% of TU respondents with corresponding Rejsekort travel cards by aligning the reported travel behaviors in the survey with actual recorded trips in the Rejsekort system. The study categorizes trips into three types: train, bus, and mixed modes, and analyzes the reporting accuracy within these categories.
The findings reveal a median time reporting error of 11.34 minutes, with an interquartile range of 28.14 minutes. The study identifies several factors that influence reporting accuracy. For instance, it was found that females generally report their travel times more accurately than males. Individuals with fixed schedules, such as students and employees, tend to be more accurate in reporting their trips than those with flexible schedules. Additionally, trips reported on weekdays are more accurately recalled compared to those reported on weekends and holidays. The mode of survey also plays a role, with internet-based surveys leading to higher accuracy than telephone-based surveys. Geographically, trips in Jutland were reported with greater accuracy compared to those in Zealand and Funen.
The paper highlights the potential for improving travel survey design by considering these findings, particularly by addressing specific demographic groups or travel modes that are prone to reporting errors. The insights from this study can help in correcting and adjusting survey data, leading to more reliable transport models and planning.
However, the study acknowledges certain limitations. For example, respondents who reported only one trip per day were excluded due to difficulties in matching such cases. Additionally, there may be inaccuracies in matching due to errors in reporting station names or instances where travelers did not tap out at the correct locations.
Overall, the study concludes that while there are significant reporting errors in the Danish National Travel Survey, these errors can be systematically analyzed and corrected using smart card data, thereby enhancing the reliability of survey-based transport studies.
You can click here to check the slides!
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