To prevent various types of trouble, the carriages used by the royal family and its guards all had systems installed that allowed their locations to be detected. Knight Leader knelt on the asphalt road, placed his hand on it, and muttered something. When he did, a number of lines appeared along the road as if they had been painted on with luminous paint. They indicated where the carriages’ wheels had passed.
“Its distance is around 2000 meters. Its speed is 50 kilometers per hour. Given the direction, it seems she is heading to Canterbury via Dover in order to circumvent the mountains.”

Toaru Majutsu no Index Vol. 17 ch.4 pt.6