Detroit Free Press Marathon 2024, course map and altimetry

Notes on the calculation of the length of the route, on the altimetry and on the slope

Note 1: the length of the route is calculated using the geographic coordinates of the points that compose it, thanks to a specific formula. This value may differ slightly from the official length declared by the organizers of the race, which is valid in case of discrepancies.
Note 2: the altimetry may not correspond exactly to the real values. For routes obtained via Google API, it is possible that the altitude is that of the terrain, without considering the presence of any tunnels or viaducts. If, however, the route was obtained from GPS tracking (for example with sports watches), the error is arbitrary and may depend both on the GPS coverage at the time it was recorded and on the performance of the device used.
Note 3: the percentage slope is found by calculating considering sections of at least 50 meters and is subsequently subjected to a "smoothing" process to reduce the possibility of artifacts and obtain a more realistic trend. For classification purposes, roads with gradients between -3% and +3% are considered flat, those with gradients between +3% and +7% are uphill, and those with gradients greater than +7% are considered steep. The same classification applies to descents. This classification is to be considered arbitrary and is a choice of goandrace.com.