41 CFR 301-70.503: -70.503 Defining actual cost and constructive cost for travel interruption due to incapacitating illness or injury.

(a) Actual cost of travel will be the transportation expenses incurred and en route per diem expenses for the travel as actually performed from the point of interruption to the alternate location and from the alternate location to the TDY assignment. No per diem expenses are allowed for time spent at the alternate location if confined to a medical facility.

(b) Constructive cost is the sum of travel and transportation expenses the employee would reasonably have incurred for round-trip travel between the official station and the alternate location plus per diem expenses calculated for the appropriate en route travel time. The calculation will necessarily involve assumptions. Examples of related expenses that could be considered constructive costs include, but are not limited to, taxi and TNC fares, baggage fees, rental car costs, tolls, ferry fees, and parking charges.