80 Ill. Adm. Code 3000.310
Routing
Section 3000
Section 3000.310 Routing
All travel shall be by the most
direct route. Expenses due to deviations for convenience shall be borne by the
employee. Distances between destinations shall be as shown on the Illinois
Highway Map published by the Secretary of State. Where no mileages are
available, odometer readings shall be used. Mileage in and around a city of
destination may be claimed as such.