[Reading Science] 400m Athletics Track, What Is the Length of Each Lane?

The starting line of the 400m track race. The distance difference between the athletes starting in lane 1 and lane 8 exceeds 50 meters.
[Photo by YouTube screenshot]

[Asia Economy Reporter Kim Jong-hwa] The highlight of the Olympics is the athletics events. Among athletics, middle-distance races on the track are the most popular. The track drawn on the stadium where athletics events take place is usually 400m long and has 8 lanes.

The 100m sprint, known as the crown jewel of athletics, is run on a straight track, but the 200m and 400m sprints also include curved sections. The 200m race covers half the track, while the 400m race completes one full lap. However, the length of the innermost lane and the outermost lane in the 200m and 400m races visibly differ.

Therefore, the starting points for runners in the 200m and 400m races differ for each lane. How much is the length difference between lanes? Even after adjusting the starting points to account for the length difference, is it just my illusion that runners in the inner lanes seem to have an advantage?

First, let's calculate the length of each lane. If you cut and gather the curved sections at both ends of the innermost lane 1, it forms a circle. Since the straight sections are all the same length, we only need to calculate the length of the curved sections.

The formula for the circumference (l) of a circle is 'l = 2πr', where π is pi and r is the radius. This formula applies to the innermost lane 1. For lane 2, the circumference of the curve is calculated by adding the lane width to the radius. For example, in l = 2πr, adding the lane width between lane 1 and lane 2 results in 'l = 2π(r + lane width)'.

The International Association of Athletics Federations (IAAF) regulates lane widths to be between 36 and 48 inches. This means the width can vary between stadiums rather than being fixed. Most international standard tracks set the lane width to 48 inches (approximately 121.92 cm).

However, domestic regulations differ. The Korea Association of Athletics Federations sets the lane width between 122 and 125 cm. They usually use the widest width of 125 cm as the standard. Nowadays, school stadiums in Korea are smaller, and many have straight sections shorter than 100m. In such cases, they sometimes narrow the lane widths or create mini tracks with shorter straight distances, deviating from the regulations.

This is why international standard stadiums and official records matter. The most important point is whether the length of the innermost lane 1 is exactly 400m. According to measurements from a Korean university, the distance difference between lanes varies significantly depending on the lane width.

Small-scale stadium tracks typically have lane widths of 42 inches (about 106.68 cm). Assuming the innermost lane 1 is exactly 400m, calculating each lane's distance using the formula 'l = 2π(r + lane width)' plus the straight section length results in lane 1 being 400m, lane 4 in the middle being 419m, and lane 8 at the outermost being 445m.

If designed according to the Korea Association of Athletics Federations' regulation of 125 cm lane width, the length difference between lane 1 and lane 8 is a whopping 54m. The exact lengths are: lane 1 - 400.00566m, lane 2 - 407.23134m, lane 3 - 415.08534m, lane 4 - 422.93934m, lane 5 - 430.79334m, lane 6 - 438.64734m, lane 7 - 446.50134m, lane 8 - 454.35534m.

Starting line view of the 200m sprint in track and field. The distance difference between each lane is not significant.
[Photo by YouTube screen capture]

When running 400m, the distance between lanes must be more than 7m apart for each lane to cover the same distance. Most stadiums recognized for official records in Korea have lane widths of 125 cm. This means that a runner starting in lane 8 actually runs about 54m ahead compared to a runner starting in lane 1.

However, in actual competitions, runners prefer lanes 3 to 6. This is due to the degree of curvature of the corners. When running on a curved track, maximum speed is achieved by balancing centrifugal and centripetal forces. Lanes 1 and 2 have the sharpest curves, while lanes 7 and 8 are too gentle, causing problems in energy distribution.

In sections with sharp curvature, the centrifugal force is strong, so runners must control their bodies to prevent being pushed outward. Therefore, runners prefer middle lanes where they can distribute their energy more evenly. The runner with the best preliminary time is assigned a middle lane in the finals. Now you understand why athletes strive for good preliminary results.