Brown Family Sports · course analysis

Three lines, 500 metres at a time

2026 Servus Edmonton Half Marathon · 16 August 2026 · what the organiser published, what was certified, and what my watch recorded

tl;dr

What actually happened

Credit where due: this mechanism was first argued publicly by Rory Linkletter — who won the race and titled his Strava upload “21.1 + 800m” — in an Instagram reel and a thread on X: a ~700 m construction detour was meant to be offset by repositioning the turnaround, but the turnaround came back roughly half as far as it needed to. Every number in that claim checks out against the primary documents. What follows is the independent verification — none of it sourced from the reel — and as of the evening of August 18 it is no longer a hypothesis: the organisers have admitted it (their number: +674.7 m; ours, derived first: +683 m).

Sept 15, 2025 — Wellington Bridge (102 Av, 130–132 St) closes to all modes; the City's own pedestrian detour is 130 St → 104 Av → 132 St
City bulletin
Oct 23, 2025 — revised certificate "2025A" registered: map adds the jog, moves the turn, keeps 21.0975 km
CAN-2025-108
June 23, 2026 — organiser's map finalised: "All 2026 routes have been finalized"
racepoint.ca
Pre-race — Event Guide p.13, "Wellington Bridge construction detour NEW": “This detour has been calculated into the overall certified course distances”
2026 Event Guide
Aug 16 — race day. Winner's Strava: “21.1 + 800m”
Aug 17 — organisers defend the course: “The detour added roughly 712 metres, and the distance taken from the west end turnaround was roughly 690 metres” — a per-direction addition netted against a both-directions subtraction
Canadian Running
Aug 18 (evening) — apology to participants: the turnaround “did not fully offset the addition of the detour”; net +674.7 m; “We take full responsibility”; working with Athletics Canada
CTV / participant email
The organisers' full statement — August 18, 2026, 6:09 pm (unedited)

“Updated statement” from race director Tom Keogh, emailed to registered participants and received directly by this author. Reproduced in full:

The Edmonton Marathon’s previous statement detailing confidence in the course certification process was issued with the best information it had at the time. Since then, and after receiving notes from participants, including elite athletes that the course ran longer than its certified distance, we undertook a detailed review of the physical measurement of the certified course. That review has identified an error in how this year’s detour related course adjustments were calculated and for that we sincerely apologize. The additional distance added for the Wellington Bridge detour was partially offset with adjustments made to the course’s west end turnaround point. Upon review it was determined that the turnaround point did not fully offset the addition of the detour, which resulted in a net increase to the distance of the half marathon and marathon courses of 674.7m.

The event owns this error, and we take full responsibility. We appreciate the many participants who have emailed and the ones that we have followed up with to have additional conversations. While we pursued the highest level of professional course measurement and certification available, an error occurred.

We do not take this lightly. We understand that every participant arrives at the start line having invested months of dedicated training, hard work, courage and deeply held goals. We also understand we hosted the nation’s best athletes and their finishing times did not truly reflect their amazing performances. We also understand the connection this event has with our city and its pride in delivering exceptional world class events.

The integrity of the course distance is fundamental and we acknowledge that we did not deliver the standard participants deserved. We recognize many participants ran qualifying times for future races, including Boston. We are working directly with Athletics Canada and other relevant partners to determine how this year’s results can be recognized.

Moving ahead, we will review our certification processes with our partners and ensure this error does not happen again.

We thank everyone for their patience as we work through this and anyone with specific questions or concerns is encouraged to contact the Edmonton Marathon directly at info@edmontonmarathon.ca

Tom Keogh, Race Director, Edmonton Marathon

*Note: The 10km event was not professionally certified with physical measurement and not part of this statement.

The 2025 course is the trusted baseline. Certificate CAN-2025-056 was genuinely measured by bicycle on 2025-06-08 (LaMontagne & Zimmerman) and — unlike the 2026 papers — publishes its full per-kilometre GPS waypoint table. That course ran straight along 102 Av and turned at 87 Av × 138 St (Buena Vista Rd), at exactly 10,584 m.

The 2026 course changed twice. From the organiser's own map data and the 2026 certificate sheet: (1) a jog off 102 Av up to 104 Av and back — leaving 102 Av about 4.1 km into the course, 910 m of detour replacing 256 m of straight road, i.e. +654 m each way, +1308 m in total; and (2) the turnaround pulled back from Buena Vista to Valleyview Cres — by ~312 m along the route (two independent estimates: 293 m from the certificate's own waypoint symmetry, 331 m from the organiser's drawn 2025 line).

2025 certified course (ridden 2025-06-08)
21,098 m
+ construction detour, run out AND back
+1308 m
− turnaround pulled back ~312 m, saves twice
−624 m
= the course actually run in 2026
~21,781 m
what the certificate still claims
21,098 m
shortfall — uncompensated course
+683 m

The rule that makes this a blunder rather than a judgment call: on an out-and-back, moving the turnaround one metre closer removes two metres of course — a metre you no longer run out, and a metre you no longer run back. Absorbing a 654 m-each-way detour therefore requires pulling the turn back the full 654 m. It was pulled back ~312 m — half — which is precisely the number you get if you treat the detour as something run once.

The stairstep — my watch against the 2025 certificate's own waypoints

This is the part that removes all doubt. The 2025 certificate publishes GPS coordinates for every kilometre mark of the old course. Most of that course is unchanged in 2026, so my watch should pass each surviving waypoint at its certified distance — and where the course changed, the difference should jump by a predictable amount, in a stairstep: 0 before the detour → +654 after it → +654 − 624 = ~+30 after the shortened turnaround → +683 once the detour is crossed again on the way home. Here is every waypoint:

2025 waypointcertified atmy watchdifferencepredicted
1km1,000997-30
2km2,0001,999-10
3km3,0003,002+20
4km4,0004,00000
5km5,0005,641+641+654
6km6,0006,655+655+654
7km7,0007,685+685+654
8km8,0008,695+695+654
9km9,0009,706+706+654
10km *10,00010,738+738+654
11km *11,00010,852-148+29
12km12,00012,134+134+29
13km13,00013,150+150+29
14km14,00014,158+158+29
15km *15,00014,399-601+29
16km16,00016,186+186+29
17km17,00017,852+852+683
18km18,00018,847+847+683
19km *19,00019,846+846+683
20km20,00020,843+843+683
21km21,00021,847+847+683

* Four greyed rows sit inside the changed turnaround zone, on a divided roadway, or carry a scan-transcription doubt — flagged in the archived data, not silently dropped. The old Buena Vista turn point itself is 206 m from anywhere I ran: the 2026 course simply never goes there. Differences above prediction grow slightly with distance — that is ordinary GPS over-read (~0.7% for my watch), visible as the drift within each flat step.

The extra distance appears exactly where the course changed, and nowhere else. Kilometres 1–4: dead on. The jump to +641 happens precisely across the detour. The drop at the turnaround gives back ~620 m. The second crossing of the detour adds it again. No other reading of this table exists.

The paper trail, in one paragraph. CAN-2025-056: ridden 2025-06-08, registered 2025-06-18 — straight 102 Av, turn at Buena Vista, waypoints published. CAN-2025-108 "2025A": registered 2025-10-23, two months after the 2025 race — its map adds the 104 Av jog and moves the turn to Valleyview Cres, yet its route-descriptor text still reads "westbound to Buena Vista Dr turn point", and it claims the same 21.0975 km. The 2026 renewals (CAN-2025-056A / 108A, "measured 2026-05-31") carry the changed map and the same distance. Somewhere in that chain, a course that had genuinely been 21.0975 km stopped being 21.0975 km, and the number on the paper never moved.

The plain-English version

A half marathon has to be exactly 21.0975 km. Someone proves it by riding the route on a bicycle with a counting wheel, and a certificate gets issued. That happened here — in 2025. The 2025 ride is real, documented, and it even published the GPS location of every kilometre mark.

Then, for 2026, construction closed part of the route. The fix: go around the closed bit (which makes the course longer), and move the turnaround point closer (which makes it shorter). Do both by the right amounts and the course is still exactly 21.0975 km.

Here's the catch. This course is an out-and-back — you run every road twice, once out, once home. The detour around the construction gets run twice, so it adds 1308 m. But moving the turnaround closer also counts twice — a metre you don't run out is also a metre you don't run back. So to cancel a 654 m detour, the turnaround had to move 654 m. It moved about 312 m — half as far as it needed to. Exactly the mistake you'd make if you forgot the detour was run both ways.

Result: everyone ran roughly 680 m further than the certificate says. Six runners' watches, the race's own course map, and the certificates themselves all point at the same number — and on the evening of August 18 the organisers confirmed it, apologising to participants for a net +674.7 m. The watches weren't wrong. The paperwork was.

This replaces an earlier version that was wrong. That version treated a second line in the organiser's map data, labelled “21K Markers”, as a measurement line and localised a deviation against it. It is not a measurement line — it is a coarser drawing of the same route that cuts diagonal chords across corners. Every hotspot built on it was an artifact. This page is built only on sources that can be cited and checked, and it reaches a different conclusion.

The three lines

21.85 km

A · Posted

The organiser's own interactive route map — the “View Route Map” link on edmontonmarathon.ca. This is the line the map's 21K option draws. The organiser labels it 21,098 m — the route as they drew it is +753 m longer than its own label.

21.10 km

B · Certified

World Athletics / AIMS certificate CAN-2025-056A, measurer Marcel LaMontagne (Grade A), measured 2026-05-31, race date 2026-08-16, expires 2029-12-31. Registered via Athletics Canada. The certificate states a distance, not a drawable route — its 2026 per-kilometre waypoints are not published. The 2025 certificate's waypoints are, and they power the stairstep above.

21.95 km

C · My GPX

COROS, 5,094 points, 1 s sampling, median step 2.93 m, no dropouts. Jitter-filtered 21.94 km — only 7 m of the total is sub-1.5 m noise, so this is a clean track.

The map

One pill per 500 m of course, named for the streets it runs between and tagged with how much further my watch travelled than the posted line over that stretch — worst offender first (the small number is the segment's start km). Click a pill to zoom the map to that segment. Grey is inside GPS noise; the orange one is the turnaround.

Whole course — 21.85 km
Pick a segment above to zoom in.

Solid green: the 2026 course as published. Dashed gold: where the 2025 certified course differed — straight across the now-closed Wellington Bridge, and onward to the old Buena Vista turnaround. Red: a runner's actual race track. Gold markers: the certificates' fixed points. Everywhere the gold dashes are absent, the 2025 and 2026 courses are identical.

What the certificate actually says

The certificate is not just a number. Its map sheet defines the course by a street-by-street list and two GPS anchors, and it states the measurement convention:

“From start line on Jasper Av to finish line at same location, measured for certification runners restricted to Right of Centre in outbound & return directions, all corners are to be coned and marshalled.” — and separately, “All Km Waypoint locations (each km) are GPS referenced.”

That matters twice over. It tells us the certified distance describes a specific lane discipline, not an abstract centreline. And it tells us the per-kilometre waypoints exist — which is exactly the missing piece needed to put line B on this table.

Checking both against the certificate's two fixed points

The certificate names two exact spots on the ground: the start/finish line on Jasper Av, and the turn point — a mark on the curb by a manhole on Valleyview Cres. Those coordinates are printed on a scanned map, so a couple of digits were hard to read; I settled them by testing which reading actually lands on the road instead of squinting at the image. Distance from each fixed point to each line:

Certified start/finish → nearest point on posted line
1.1 m
Certified start/finish → nearest point on my track
10.1 m
Certified turn point → nearest point on my track
0.9 m
Certified turn point → nearest point on posted line
51.7 m

My track passes 0.9 m from the certified turn point — I turned where the certificate says to turn. The posted line misses that same point by 51.7 m. At the one place where the certificate pins the course to a physical mark, the published map is the line that disagrees.

Every 500 m, side by side

The course chopped into 500 m pieces. For each piece: how long it is on the race's map, how far my watch says I actually travelled over it, and the difference. The last two columns are how far sideways I was from their line — normal running-the-tangents drift, not a wrong turn. All figures are metres except the first column. Click any row to zoom the map to it.

Race kmStreetsTheir mapMy watchDifferenceTypically offWorst off
0.00–0.50Jasper Av500507.6+7.62.013.5
0.50–1.00Jasper Av500504.2+4.21.93.6
1.00–1.50Jasper Av500499.9-0.12.76.5
1.50–2.00Jasper Av500501.9+1.94.96.1
2.00–2.50Jasper Av500499.1-0.94.76.1
2.50–3.00Jasper Av500506.9+6.95.06.6
3.00–3.50Jasper Av → 102 Av500492.3-7.72.06.1
3.50–4.00102 Av500499.9-0.13.45.0
4.00–4.50102 Av → 130 St → 104 Av500482.0-18.03.98.3
4.50–5.00104 Av → 132 St → 102 Av MUP500497.9-2.11.42.5
5.00–5.50102 Av MUP → 102 Av → St. George's Cr500504.1+4.12.63.3
5.50–6.00St. George's Cr500492.0-8.01.63.4
6.00–6.50St. George's Cr → Ravine Dr500504.9+4.91.73.3
6.50–7.00Ravine Dr500503.7+3.71.32.1
7.00–7.50Ravine Dr → 142 St → Summit Dr500499.4-0.62.14.0
7.50–8.00Summit Dr → Riverside Dr500502.6+2.61.02.5
8.00–8.50Riverside Dr → 95 Av500504.2+4.21.23.0
8.50–9.0095 Av → 142 St → Valleyview Dr500495.8-4.24.04.9
9.00–9.50Valleyview Dr500506.6+6.61.93.7
9.50–10.00Valleyview Dr → 91 Av → 139 St500493.7-6.30.92.3
10.00–10.50139 St → 90 Av → Valleyview Cr500500.6+0.60.93.1
10.50–11.00Valleyview Cr500608.4+108.41.929.6
11.00–11.50Valleyview Cr → Valleyview Dr500496.6-3.43.65.5
11.50–12.00Valleyview Dr → 90 Av → 140 St500508.3+8.32.24.4
12.00–12.50140 St → 91 Av → Valleyview Dr500499.3-0.73.14.8
12.50–13.00Valleyview Dr → 142 St500503.4+3.41.13.6
13.00–13.50142 St → 95 Av500496.7-3.31.43.5
13.50–14.0095 Av → Riverside Dr500496.1-3.91.93.3
14.00–14.50Riverside Dr → Summit Dr500504.9+4.91.33.8
14.50–15.00Summit Dr → 142 St → Ravine Dr500496.9-3.13.56.2
15.00–15.50Ravine Dr500499.9-0.12.84.6
15.50–16.00Ravine Dr → St. George's Cr500494.1-5.91.44.7
16.00–16.50St. George's Cr → 102 Av500494.6-5.41.53.6
16.50–17.00102 Av → 132 St500497.0-3.01.53.9
17.00–17.50132 St → 104 Av → 130 St500491.9-8.11.83.0
17.50–18.00130 St → 102 Av500497.0-3.03.39.4
18.00–18.50102 Av → 124 St500506.3+6.33.57.6
18.50–19.00124 St → Jasper Av500500.5+0.57.412.0
19.00–19.50Jasper Av500494.8-5.22.010.5
19.50–20.00Jasper Av500501.7+1.75.48.0
20.00–20.50Jasper Av500500.9+0.94.911.4
20.50–21.00Jasper Av500500.0-0.02.08.7
21.00–21.50Jasper Av500504.4+4.47.411.7
21.50–21.85Jasper Av351356.4+5.54.07.6

Read the difference column. 43 of 44 pieces sit inside ordinary GPS wobble — the typical piece is out by just 4.1 m in 500. Over the whole race that adds to +98 m (0.45%), and I was a typical 2.42 m sideways from their line. I ran the route they published. There is no detour hiding in this table.

One piece breaks the pattern: Valleyview Cr, 10.50–11.00 km, at +108 m. That is the turnaround, and it is where their drawn line stops 51.7 m short of the turn point the certificate names. I ran out to the real turn and back; their map doesn't draw that bit. So this one is their drawing falling short, not me running extra.

Where the extra distance builds up

The certified street list is a palindrome hinged on “Valleyview Cr — reverse routing”, so the turn point sits at half the certified distance. Splitting my run there:

Certified distance at the turn (assumed half)
10549 m
My distance at the turn
10979 m
Excess, start → turn
+430 m (4.08%)
Excess, turn → finish
+422 m (4%)

The two halves carry 4.08% and 4% — the same rate, to within a rounding error. The excess accumulates symmetrically. That ruled out a missed turn or a one-sided error early on — and it is exactly what the real mechanism produces: an out-and-back detour is crossed once in each half, and the shortened turnaround sits at the hinge, so both halves carry the same surplus. The symmetry that first looked like "no detour anywhere" turns out to be the signature of a detour run both ways.

Accounting for the whole gap

The +852 m between my watch and the certificate splits at its natural seam almost entirely one way:

Me vs the route they published
+98 m  (11.5%)
Their published route vs the certified distance
+753 m  (88.5%)

Nearly nine tenths of the discrepancy is between the organiser's own map and the organiser's own certificate. It has nothing to do with how I ran. I tracked their published line to within 0.45%.

It isn't a sloppy drawing either. Straighten the published line until every point is within 3 m of where it was and it only loses 13 m; within 5 m, only 45 m. The same test on my GPS track loses 61 m and 104 m. Neither line is padded with wobble. Both describe a genuine 21.85-ish km path.

A hypothesis I published here earlier, now retired. Before the certificates surfaced, this page attributed the gap to tangents-versus-bends: the theory that the certificate measures the shortest legal line while runners and map drawings follow every curve. The organiser's own map data falsifies that: their 2025-option drawn line, by the same cartographer at the same fidelity, measures 21,122 m — within 25 m of certified. Faithful drawings of this family of courses track the certified length closely. A drawing does not gain 750 m from bends; the 2026 route gained it from being a different, longer route. The corner/tangent effect is real but worth tens of metres here, not hundreds — it lives inside the GPS drift, not the headline.

Now with 6 runners — and ~40 more offering

6 tracks from the 2026 half have been ingested and measured through the identical pipeline — same distance calculation, same certified baseline, no smoothing applied to any of them. One is set aside because that runner's watch kept recording after the finish, leaving 5 in the statistics. Beyond these, roughly forty runners have volunteered their files and a named roster of 22 is queued for ingestion. Names are withheld here; this is other people's race data and the aggregate makes the point without it. (Some of it speaks for itself anyway — public activity titles in the roster include "course too long!" and "edmonton half! +1km".)

Runners over-reading the certified distance
6 of 6
Tightest track of the group
+595 m  (2.82%)
Median over-read
+852 m  (4.04%)
Widest track of the group
+1002 m  (4.75%)
Typical GPS over-read for any road race
0.5–1.5%
Every runner's distance from the posted line
~1.6 m median
Every runner's closest pass to the certified turn point
within 2 m

I got one half of my prediction wrong and should say so. I wrote that other tracks would cluster tightly around mine. They don't — they spread 407 m, from 2.82% to 4.75%. That is not a cluster.

But the spread is the stronger result. If a course is simply mis-measured, every runner is long by the same amount — a constant offset. If the gap is about which line you run, you get a spread with a floor above zero. That is exactly the shape here: nobody came within +595 m of the certified distance, and even the tightest runner in the group over-read by 2.82% — still well outside the 0.5–1.5% a GPS watch is expected to add on any course.

And the median lands on the drawn route. The median over-read is +852 m; the organiser's own published line is +753 m longer than certified. Those agree to 98 m — around 0.5% of the course. The typical runner ran the map's bend-following line, and that line is roughly +753 m longer than the number on the certificate.

Every one of them passed within 2 m of the certified turn point and turned at almost exactly half their total distance. Nobody took a wrong turn. They ran the same course, on the same line, and all came up long together.

Two honest caveats on this group. 5 tracks is a small sample, self-selected from runners who were already curious about the distance — that skews toward people whose watches read long. And most were exported through a third-party service that applies its own processing before you get the file; a separate analysis of the same runners using noise-reduction landed 150–200 m lower than these raw figures. It reached the same conclusion by the same reasoning, but the exact metres depend on the method, and I would rather show the conservative raw number and say so. More tracks would fix both problems.

How was this signed off? An open investigation

The apology explains the arithmetic. It does not explain how that arithmetic became a certificate. Three governing texts say it shouldn't have been possible, and the paper trail shows where it slipped through. This section is our own investigation, ongoing; every document is linked.

What the rules say. The World Athletics certificate carries its own kill-switch on page one: it stays valid only if the course is “unchanged in any way”, and “any modifications to the course, however minimal, will nullify this Certificate and require a new measurement to be undertaken”. Athletics Canada's course-measurement program states: “Should a course be changed in any way from one year to the next, it must be re-measured and a new certification issued.” And Athletics Canada's current written policy (March 2026) repeats the rule — then opens a door in the very next sentence: “in cases of slight alterations, a full remeasurement may not be required and an amendment to an existing certification may be issued.” No definition of “slight”. No stated arithmetic protocol. No independent check. A detour of 654 m each way plus a relocated turnaround went through a door built for slight alterations.

What the paper trail shows. The revised course — detour and new turnaround — was prepared well in advance: an Athletics Canada certificate for the “2025A West” configuration was nationally certified on June 29, 2025, eleven weeks before the bridge even closed, citing the same June 8, 2025 measurement ride as the original course. Three details on that revised certificate's own map sheet suggest the new turnaround was computed on paper rather than established on the road:

Its route descriptor still reads “westbound to Buena Vista Dr turn point” — the OLD turnaround, on a map whose drawing turns at Valleyview Cres
recycled text
Its street list still includes 137 St / 89 Av / 138 St — the abandoned extension past the new turn
recycled text
Its turn-point inset annotates the curb mark: “not painted”
no physical mark

A course measured wheel-on-road gets its turnaround wherever the calibrated counter says the distance completes — a full ride cannot miss by ~342 m. A turnaround placed by subtraction can, and the organisers' own apology uses exactly that word: an error in how the adjustments were “calculated”.

The asymmetry that let it survive. Athletics Canada's certificate template voids itself “if any changes are made to the course which results in a course that is less than the stated distance”. Less than. A course that runs long does not trip the written void-clause — the certification system's tripwires all face one direction, guarding records against short courses, with nothing pointed at the direction that cost every runner in this field two and a half minutes.

The open questions — each one answerable from a specific document or by a specific person:

1. Was the 2025A/2026 configuration ever ridden end-to-end with a calibrated bicycle — and if so, on what date, with what recorded total? (The full measurement report filed with the certificates would show this line by line.)
2. What was measured on May 31, 2026, the measurement date the 2026 certificates carry — a full re-ride, the detour segment only, or nothing new?
3. Who reviewed the amendment arithmetic before the national certification of June 29, 2025 and the international registration of October 23, 2025 — and does the review process include any check that catches a doubled-versus-single adjustment?
4. The organiser's pre-race Event Guide told runners the detour “has been calculated into the overall certified course distances”. Who verified that sentence before it was published?
5. The initial defence cited an “up to 1 per cent” tolerance. The measurement standard's actual safeguard is the Short Course Prevention Factor of 0.1% — added so courses cannot be short, not a licence to be long. Where did the 1% figure come from?

Athletics Canada's certificates direct inquiries to coursemeasurement@athletics.ca; the organisers direct questions to info@edmontonmarathon.ca. The full measurement report is the next document to request through those channels, and answers will be published here as they arrive — including anything that proves parts of this section wrong.

What is still missing, precisely

The 2025 waypoints closed the biggest gap on this page — the stairstep above is built on them. What remains open:

1. The 2026 measurement report. The 2026 certificates say "measured 2026-05-31" and claim 21.0975 km for a geometry that cannot be shorter than ~21.7 km — and the organisers' Aug 17 statement says a Grade A measurer "was present on race day". What was actually ridden, and how the adjustment was signed off, is a question only the full measurement report (or Marcel LaMontagne and Bernard Conway themselves) can answer. The apology says they are "working directly with Athletics Canada" — that review is the thing to watch.

2. What happens to the results. This was the Canadian Half Marathon Championships. Times were run on a course now admitted to be ~675 m long — Boston qualifiers, records and championship standards hang on what Athletics Canada does next. As of publication the race's own homepage still carries no statement; the admission lives in a participant email and news coverage.

3. More tracks. 5 runners establish the pattern; forty make it unanswerable — including exactly where every watch gained its extra metres. That is what the upload endpoints are for.

Sources

Everything above is derived from public documents and data. Nothing on this page is a recollection or an estimate — every source is linked so you can check it yourself.

1 · The certified course
World Athletics / AIMS International Measurement Certificate CAN-2025-056A — 21097.5 m, measurer Marcel LaMontagne (AIMS Grade A), measured 2026-05-31, race date 2026-08-16, administrator Bernard Conway, expires 2029-12-31.
Certificate CAN-2025-056A (PDF)
A second certificate, CAN-2025-108A ("Edmonton 2026 West Half Marathon"), carries an identical map sheet — same source.
Both found via the Athletics Canada certified-course register: acroad.ca → Course Measurement → Certified Courses. Retrieved 2026-08-18.
1b · The 2025 certificates — the baseline and the revision
CAN-2025-056 — the 2025 course, measured 2025-06-08 by Marcel LaMontagne & Darren Zimmerman, registered 2025-06-18. Straight along 102 Av; turn at 87 Av × 138 St (Buena Vista Rd), 53.519389, -113.559407, at 10,584 m. Publishes the full per-km GPS waypoint table used for the stairstep above.
CAN-2025-108 "Edmonton 2025A Half Marathon" — registered 2025-10-23; its map adds the 104 Av jog and moves the turn to Valleyview Cres (53.521228, -113.557920) while its route descriptor still reads "westbound to Buena Vista Dr turn point". Same 21.0975 km claim.
Athletics Canada's parallel certificate AB-2025-015-BDC shows the same revised configuration nationally certified June 29, 2025 — before the bridge closed — with the recycled route text and the “not painted” turn-point annotation discussed in the investigation section.
1e · The governing rules
World Athletics / AIMS certificate text (page one of every certificate above): valid only while the course is “unchanged in any way”; any modification “however minimal, will nullify this Certificate and require a new measurement”.
Athletics Canada course-measurement program: acroad.ca → Course Measurement — “Should a course be changed in any way from one year to the next, it must be re-measured and a new certification issued.”
Athletics Canada, Road Race Sanctioning and Course Measurement Certification Policy (March 16, 2026), §6 Course Changes — the re-measurement rule and the “slight alterations” amendment exception quoted above. Note the policy's date: it post-dates the October 2025 registration; it is cited as the current codification of the pathway, not necessarily the text in force at the time.
Athletics Canada certificate template, “Official Notice”: certification becomes void only for changes resulting in a course “less than the stated distance”.
1c · The mechanism claim being verified
Instagram reel and X thread by Rory Linkletter (race winner): instagram.com/reels/DcMJ3m1C5HF · x.com/thepapalinks — a ~700 m construction detour compensated by a turnaround move of roughly half what was needed. Our independent measurements from the documents above: detour 654 m each way; turnaround moved ~312 m (needed 654 m). The claim holds. The verification here shares no data with the reel. A Reddit user (u/LostTheElectrons) independently reached the same numbers from map comparison two days before the admission.
1d · The construction record, and the admission
The closure: City of Edmonton, Wellington Bridge Replacement — 102 Av between 130 St and 132 St, closed to all modes from the week of 2025-09-15 through end of 2026; the City's prescribed pedestrian detour is 130 St / 132 St to 104 Av, exactly the race's jog. edmonton.ca project page · construction bulletin (PDF)
The organiser's record of the change: 2026 Event Guide, p.13, "Wellington Bridge construction detour NEW" — turn-by-turn detour directions for both directions of travel, and the sentence “This detour has been calculated into the overall certified course distances.” Event Guide (PDF)
The defence (Aug 17): race director Tom Keogh — “The detour added roughly 712 metres, and the distance taken from the west end turnaround was roughly 690 metres”; Athletics Canada initially backed the certification. Canadian Running · CBC · Runner's World
The admission (Aug 18, 6:09 pm): “Updated statement” from race director Tom Keogh, emailed to participants — received directly by this author as a registered runner. The turnaround “did not fully offset the addition of the detour”, net +674.7 m on half and full; “The event owns this error, and we take full responsibility”; working with Athletics Canada “to determine how this year's results can be recognized”. A footnote adds that the 10K “was not professionally certified with physical measurement”. CTV News · CP via Yahoo · full email text
Independent corroboration: same-runner year-over-year Garmin files — 21.25/21.30/21.35 km on the 2025 course vs 21.99/22.02 km in 2026 (r/Edmonton, r/AdvancedRunning); chip splits slow for the whole field across the 10–13.7 km turnaround section. Our +683 m was derived from the certificates and map geometry before the admission; the organisers' review landed on +674.7 m.
2 · The published route
The race's own interactive map, reached from edmontonmarathon.cathe RacePoint course map. Line A is the route the map's own 21K option draws, taken from the map's public route data, which labels it "21K" at 21,098 m. Map credited to RacePoint; route data last updated 2026-06-23; retrieved 2026-08-18.
3 · My track
COROS watch export, 2026-08-16, gun 7:45 am. 5,094 track points at 1 s sampling, median step 2.93 m, no dropouts. Raw and jitter-filtered distances differ by only 7 m.
4 · Street names
Reverse geocoded from OpenStreetMap via the Nominatim API, sampling each segment's start, midpoint and end, then abbreviated to match the certificate's own conventions. Map data © OpenStreetMap contributors, ODbL. Basemap tiles © CARTO. Retrieved 2026-08-18.
5 · The method
Distances along my track are measured position-to-position on the standard Earth model. Progress along the published route is measured by matching each GPS point to the route while only ever moving forward — necessary because on an out-and-back course, the outbound and return lanes of the same road sit metres apart, and a naive nearest-point match jumps between them. Certificate coordinates were transcribed from scanned map sheets, and any hard-to-read digit was resolved by testing which reading actually lands on the road. Raw source files and the full analysis are archived and available on request.
× · What I retracted
The map's route data also contains a second half-marathon line, labelled "21K Markers", at 21.06 km. An earlier version of this page treated it as a measurement line and localised a deviation against it. Nothing on the race's map ever displays that line; it sits a median 0 m from the displayed route and differs only by cutting diagonal chords across corners — in places straight through buildings. It is a coarser drawing of the same route. Every hotspot built on it was an artifact, and all of it is withdrawn.

If you think any of this is wrong, the fastest way to show it is to check the two certificates against the map data yourself — both are one click away. Corrections are welcome and will be published.

Ran Edmonton on August 16? Add your track.

Your GPS file is one more data point toward an answer that no screenshot can give. It's measured in your own browser — the raw file never has to leave your device unless you choose to archive it — and it goes into a median, not a headline. Pick your distance:

Brown Family Sports Inc. · rebuilt 2026-08-19 · Sources: certificate CAN-2025-056A (World Athletics / AIMS, via acroad.ca) · the race's published route map · COROS GPS. Source files and the full analysis are archived; the earlier conclusion drawn from the “21K Markers” line (21.06 km) is withdrawn.