Recently the work of measuring the race courses for the first Shenzhen Yantian Mountain and Sea Half Marathon was successfully completed, and the 21.0975 kilometers of the race route was officially determined, sznews.com reported Monday.

Accurate measurements of road race courses is one of the most critical steps to confirm the distance of the route. According to the World Athletics Federation, the course distance measurement of the marathon must first be calibrated 300 meters for the Jones Counter, and then the measurement will be carried out by the measuring officer himself on a bicycle for each kilometer, which is the most common method to measure the distance of the marathon course internationally – the bicycle marking method.

A calibrated bicycle fitted with a Jones Counter is the only approved method of measuring road race courses. The Jones Counter, which is mounted at the hub of the bicycle’s front wheel, is named after its inventor and the original manufacturer, Alan Jones.

The race course for the Yantian half marathon was measured by Wang Xiangying, an approved class B measurer appointed by the Chinese Athletics Association and a professor at the School of Physical Education of Shandong Normal University. The measurement took two and a half hours.