Is the value of travel time savings increasing? Analysis throughout a financial crisis

In this paper we ask the question if the value of travel time savings (VTTS) is increasing over time and continue to investigate this based on a pooled cross-section model. The analysis is based on data originating from a large-scale Danish national ongoing travel survey from 2006 to 2016 consisting of more than 400,000 trips. The period is interesting from a research perspective as it offers substantial variation in income, is characterised by structural changes due to increased urbanisation and congestion and at the same time represents a phasing-in period for mobile broadband solutions from almost no coverage to full national coverage. Several things are revealed from the analysis. It is shown that the financial crisis impacts VTTS and that the impact differs across income groups. It is also found that, over the period, VTTS increases by approximately 10%. Although this largely correspond to the growth in the disposable income, it is not possible to point to precise confounders and their relative importance. Rather the paper suggest that the increase in VTTS is caused by a mix of different cofounders, which include (but is not limited to) increasing travel distances, increasing congestion and increasing income.