The course underwent several changes after I measured.
- Before the race the specified two lanes 1.8 m wide within half the road in one section of Queensway were converted to two 3.6m wide lanes by using the whole road.
- Also during the race two 1.310 km laps were accidentally run at the start rather than a single lap. The organisers compensated by shortening lap 12, by making measurements with a surveyors wheel during the race and introducing a new turning point. This also involved changing another section of road from running in the East half to running in the West half. Because the shortened lap 12 remained in place for 3 hours until all the back markers had passed the point, those runners who had already passed lap 12 had a further small saving of about 1.4 m on each of lap 13 onwards.
My verification ride took place in very stable temperature conditions very early on a Sunday morning with little traffic. I had previously studied the race video and still pictures on the IAU website:race pictures, so I had been able to confirm the correct placing of cones and barriers at almost every point which I had specified. Paint marks were still in place for the lap 12 turn, and at correctly located at other specified points (start/finish/initial 1.310 km lap turn) so I was very confident about following the exact route available to runners on race day.
The result was a length of 99.903 km, so I concluded that the course was short by 97 m and that any any other verifier would also be very likely to get a result less than 99.950 km and so also prove the course short.
See the IAU's statement on the remeasurement