Each TRTKO trail and completed TRTKO run have to to meet the following TRTKO criteria:

• aid station = 1 at the start of each lap (i.e. at minimum a water drop-off location for a group run)
• minimum number of runners = 3 that complete at least the first lap
• lap distance = 5 km ~ 3.1 mi
• minimum single-track trail distance = 2/3 of a lap (i.e. 3.3 km ~ 2.1 miles)
• minimum ascent = 150 m ~ 500 ft per a lap (i.e. average +6% and -6% grade change per 1/2 lap, 2.5km)
• minimum descent = 150 m ~ 500 ft per a lap (i.e. average -6% and +6% grade change per 1/2, 2.5km)
• distance and elevation measurements = from public segments of GPS tracked runs, e.g. through strava.com (note that onthegomap.com is a useful exploratory tool to estimate lap distance, ascent, descent before a run but it does not provide accurate measurements and hence cannot be used as a substitute to an actual run that was tracked with GPS)

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• NA cutoff = 1h
• TKO limit = 40 min for the first lap, then -2 min for each successive lap
• lap target = 6 with each lap to be started together at predetermined times, see the example below (i.e. if quicker, leftover time before the next lap to be spent at the start which is also the only aid station)

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• single-day TRTKO tiebreaker = fastest last lap finished under the NA cutoff
• multi-day TRTKO tiebreaker 1 = most finished single-day TRTKO runs with all 6 laps (i.e. most no-TKO runs)
• multi-day TRTKO tiebreaker 2 = most eliminated single-day TRTKO runs with a TKO (i.e. fewest NA)
• multi-day TRTKO tiebreaker 3 = higher sum of total ascent values from each single-day TRTKO run
• multi-day TRTKO tiebreaker 4 = faster sum of last lap times finished under the NA cutoff from each single-day TRTKO run
• A multi-day TRTKO run is the same single-day TRTKO run that occurs back-to-back on consecutive days. It covers single-track trail distance longer than one marathon and is therefore an ultra run as well. It can be on the same trail or on different nearby trails for some regional variation and exploration.