Rut (roads)

, designed to guide carriages Rutting can also be intentional. The ancient Assyrians, Babylonians, Persians and Greeks constructed roads with artificial wheel-ruts deliberately cut into rock. The ruts were spaced apart from each other the same distance as the wheelspan of an ordinary carriage, and thus constituted grooves that guided the carriages on the rutway. Such ancient stone rutways connected major cities with sacred sites, such as Athens to Eleusis, Sparta to Ayklia, or Elis to Olympia. The gauge of these stone grooves was 138 to 144 cm (4 ft 6 in to 4 ft 9 in). The largest number of preserved stone trackways, over 150, are found on Malta. Some of these ancient stone rutways were very ambitious. Around 600 BC the citizens of ancient Corinth constructed the Diolkos, which some consider the world's first railway. The Diolkos was a hard poros limestone road with grooved tracks (wheel-ruts), along which large wooden flatbed cars carrying entire ships and their cargo were pulled by slaves or draft animals. The grooves were at centres. == Gauge ==

References going back to at least 1937 suggest that the "gauge" of ancient rutways, and the distance between the wheels of carts influenced the railway standard gauge of the modern era which is . The argument is that this is shown by the evidence of rutted roads marked by cart wheels dating from the Roman Empire. Snopes categorized this legend as false but commented that "... it is perhaps more fairly labelled as 'True, but for trivial and unremarkable reasons.'" The historical tendency to place the wheels of horse-drawn vehicles approximately apart probably derives from the width needed to fit a carthorse in between the shafts. In addition, while road-traveling vehicles are typically measured from the outermost portions of the wheel rims (and there is some evidence that the first railroads were measured in this way as well), it became apparent that for vehicles travelling on rails it was better to have the wheel flanges located inside the rails, and thus the distance measured on the inside of the wheels (and, by extension, the inside faces of the rail heads), was the important one. == Studded tires ==

On relatively level highways, the depth of the ruts due to carbide studded tires is relatively uniform; however, on hilly highways the ruts tend to be deeper on the uphill sections compared to the downhill and level sections. On the uphill sections, the vehicle delivers more power to the wheels to overcome gravity, thereby, increasing the shearing force of the studs against the pavement, thus resulting in an increased cutting action. Ruts are also deeper at the entry to and exit from intersections and corners, due to deceleration (braking) and acceleration. == See also ==