Timing and measurement

Three ways to time a race

World Athletics recognises three official methods (Technical Rule 19.1): hand timing; fully automatic timing "obtained from a Photo Finish System"; and transponder timing — the last only for road, race-walking, cross-country and mountain and trail events, never on the track. Each has its arithmetic. Hand times are taken "from the flash / smoke of the gun" by three timekeepers and rounded up to the next tenth (10.11 becomes 10.2); if two watches agree that time stands, if all three differ the middle one, if only two and they differ the slower. A system automatic at the finish but hand-started produces hand times; automatic at the start but not the finish produces neither.^[1] [2]

Fully automatic timing must carry a certificate of accuracy issued within four years; the camera sits in the extension of the finish line and composes an image of "at least 1000 images per second" at top-tier competitions and 100 elsewhere, synchronised to a scale in hundredths, with a start delay "equal to or less than 0.001 second" verified by a zero-control test before every session; there should be two cameras, one from each side. The rule that decides races is 19.2: the time is taken when "any part of the body of an athlete (i.e. torso, as distinguished from the head, neck, arms, legs, hands or feet) reaches the vertical plane of the nearer edge of the finish line" — and the guidelines locate the torso between "the outer end / articulation of the collarbone" and the hip line. Wheelchair racers are timed on the centre of the leading axle.^[1] [3]

Hundredths, thousandths, and which way to round

The federations do not agree on resolution, and their disagreements are principled.

Rule text in the references.^{[1] [4] [5] [6] [7] [8] [9] [10]}

Swimming's refusal to split a hundredth is the best-known case, and the reason is the pool, not the clock. A 50 m pool may measure up to 10 mm over and none under; at sprint speed a thousandth of a second is about 1.7 mm of water, so ranking to the thousandth would rank swimmers by lane length. Hence Rio 2016, where Michael Phelps, Chad le Clos and László Cseh all touched in 51.14 and shared silver — the first three-way tie in Olympic swimming — and Sochi 2014, where Dominique Gisin and Tina Maze shared downhill gold on 1:41.57 because FIS calibrates its timing to hundredths on purpose. Athletics went the other way at Paris 2024: Noah Lyles beat Kishane Thompson to 100 m gold by five thousandths of a second, 9.784 on the photo, with the photo read to a resolution the camera provides at 40,000 images a second.^{[4] [11] [12] [13] [14] [15]}

Starts, wind and distance

The start. When a certified Start Information System is in use the starter wears headphones to hear the signal that fires "when the reaction time is less than 0.100 second" (TR 16.6); any athlete responsible for a false start is disqualified, except in combined events (TR 16.8). In swimming the equipment must be "activated by the starter" and "false start detection equipment must be installed"; a relay exchange less than 0.04 s after the touch is a false start.^{[1] [4] [11]}

Wind. Non-mechanical gauges are required at top competitions and for any world record, placed beside the straight "50m from the finish line … 1.22m ± 0.05m high and not more than 2m away from the track" (30 m for the short sprints; 20 m from the board for the jumps), measuring for 10 seconds in the 100 m and 13 in the hurdles, and read "rounded to the next higher tenth" in the positive direction — +2.03 becomes +2.1, −2.03 becomes −2.0.^[1]

Distance. Field events are measured "with a calibrated steel tape or bar or with a scientific measuring device" at major competitions (fibreglass tapes elsewhere), and — the mirror image of the track — recorded "to the nearest 0.01m below the distance measured". Times round up against the athlete; distances round down against the athlete; the two rules agree on which side to err.^[1]

The swimming touchpad, and why it exists

Swimming's rules give the machine precedence over the officials: times recorded by automatic equipment "shall have precedence over the decisions of timekeepers", and only if the equipment fails, or a swimmer fails to trigger it, do the watches count — with a reswim as a last resort. The touchpad is specified: at least 2.4 m wide and 0.9 m high, 10 mm thick when closed, reaching 0.3 m above and 0.6 m below the water, activated "by a light hand touch" but not by turbulence — in practice about 1.5 kg of force against roughly 1 kg of wash — with a 25 mm black border. The backup is semi-automatic: three buttons per lane, each pressed by a separate official, and an overhead camera at 100 images a second.^[4] [11]

The pads exist because of Rome 1960. In the 100 m freestyle John Devitt and Lance Larson were both credited with 55.2; Larson's three lane watches read 55.0, 55.1 and 55.1, Devitt's three read 55.2; the first-place judges split two to one for Devitt and the second-place judges split two to one saying Devitt was second — a tie — and the chief judge, who "did not have a vote" under the rules, gave the gold to Devitt. The American appeal with film was rejected. Omega introduced the first touchpads at the 1967 Pan American Games and they have been used at every Summer Games since 1968.^[16] [17]

Review, replay and the electronic call

Sources in the references.^{[18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [42]}

The judged sports took a different route: not a camera but arithmetic. Diving cancels the two highest and two lowest of seven judges' marks before multiplying by the degree of difficulty; figure skating replaced the 6.0 with the International Judging System approved on 9 June 2004 after the Salt Lake City pairs scandal; gymnastics introduced its open-ended Code of Points in 2006 and retired the perfect 10. The trimmed mean is the judged sports' defence against a single rogue judge, developed at Competition formats.^{[4] [32] [33]}

Who holds the clock

Omega was first the Olympic Games' official timekeeper at Los Angeles 1932 — "a lone watchmaker and 30 chronographs", accurate to a tenth — and in May 2017 became the first worldwide partner committed through 2032, a century. Mexico City 1968 was "the first time that electronic timekeeping was officially used in all events"; Munich 1972 the first with results to the hundredth; and from 1977 automatic timing was required for world-record ratification. Omega's photo-finish camera went from 10,000 images a second at Rio 2016 to 40,000 at Paris 2024. Seiko has timed World Athletics' championships since 1985; Tissot the UCI since 1995 and the NBA since 2015; Longines the FIS Alpine World Cup, on a contract running through 2025–26.^{[34] [35] [36] [43] [44] [15] [37] [38] [41] [9]}

The clock has not settled everything. At Jerez on 26 October 1997 Jacques Villeneuve, Michael Schumacher and Heinz-Harald Frentzen qualified in the identical 1:21.072 and the grid was ordered by who set it first — as the current regulations still provide. And the last three seconds of the 1972 Olympic basketball final were played three times.^{[39] [10] [40]}

The reading

Measurement in sport is a set of agreements about where to stop. Every federation could publish thousandths; most decline, because a number is only as honest as the thing it measures, and a pool, a piste or a finish-line camera each carries an uncertainty of its own. Swimming's tie at the hundredth, alpine skiing's truncation and athletics' rounding-up are three answers to the same question — how to keep the published figure inside what the venue can guarantee — and the field-event rule that rounds distances down is the same principle facing the other way.

Video review followed the same logic a generation later: not to decide everything, but to overturn the "clear and obvious", within limits each sport wrote for itself — who may ask, how often, and whether the referee stays in charge. Where the review is unlimited, as with a ball on a line, the human official has been replaced; where the question is judgement, the human has been kept and the camera made to wait for an invitation.