  Travel time savings are usually the most substantial economic benefit of
transport infrastructure projects. However, questions surround whether small
time savings are as valuable per unit as larger savings. Thresholds in
individual choice behaviour are one reason cited for a discounted unit value
for small time savings. We demonstrate different approaches for modelling these
thresholds using synthetic and stated choice data. We show that the
consideration of thresholds is important, even if the discounted unit value for
small travel time savings is rejected for transport project appraisal. If an
existing threshold is ignored in model estimation, the value of travel time
savings will be biased. The presented procedure might also be useful to model
thresholds in other contexts of choice behaviour.
