BONA, GLENN

Current PI (Performance Index) blends how the runner is going right now with their career score: about 70% their most recent section and 30% their career iTRA PI. It updates every section and is the level we use to predict the next one. (Before the first section it's just the career iTRA PI; a runner with no career PI uses their latest section alone.)

Section PI is what that one section implies on its own — that single leg's pace against the reference, ignoring the rest of the race.

Read either against the runner's career iTRA PI: a higher number means they ran harder than their score predicts; lower means slower (tired, or pacing on purpose).

Expected at is our predicted arrival at the next aid station: its terrain-adjusted (“equivalent”) distance run at the Current PI's pace, plus a small allowance for fade because runners slow over a long day. It refreshes each time a section finishes.