Freight Travel Time Reliability: Planning Time Index
Truck travel times vary greatly from day to day, and drivers remember those few bad days they suffered through unexpected delays. Travel time reliability measures the extent of this unexpected delay. Planning time index represents the additional time that a shipper should budget to ensure on-time arrival 95% of the time. Different from on-time arrival, the higher the planning time index (PTI), the worse the reliability is.
From 2018 and 2019, combination truck PTI during peak hour increased statewide from 1.55 to 1.56. For a trip that would take 10 minutes in free-flow conditions, the 95th percentile travel time is 15.6 minutes with a PTI of 1.56. The shipper needs to plan an additional 5.6 minutes for the trip to arrive on time.