Arut is a depression or groove worn into a road or path by the travel of wheels or skis. Ruts can be formed by wear, as fromstudded snow tires common in cold climate areas, or they can form through the deformation of theasphalt concrete, pavement orsubbase material. In modern roads the main cause is heavily loaded trucks. These heavy loaded trucks imprint their tire impressions on roads over time, causing ruts. Rut is a common pavement distress and is often used inpavement performance modeling.[1]
Ruts prevent rainwater from flowing to the side of the road into ditches or gutters. Rainwater trapped in ruts is a common contributing factor tohydroplaning crashes. Severe ruts can impede steering if a vehicle has difficulty steering out of the rut. If it proves impossible to steer out of a rut, though forward and backward progress can be made by the vehicle, it is referred to as being stuck in the rut.
Ruts in gravel roads can be removed bygrading the road surface. Ruts in asphalt pavement can be filled with asphalt, then overlaid with another layer of asphalt, but better results can usually be achieved by grinding off the surface to restore the proper cross slope, then resurfacing. If the ruts are formed due to deformation of the subbase below the pavement, the only long-term repair is usually full-depth reconstruction of the road.
Typically rutting is reported in terms of rut depth. Rutting is measured at highway speeds with a laser/inertialprofilograph.
The termstuck in a rut can be used figuratively to refer to a situation in which, as time progresses, the situation is unable to be changed or steered in a desired way.
Rutting can also be intentional. Theancient Assyrians,Babylonians,Persians andGreeks 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 withsacred sites, such asAthens toEleusis,Sparta to Ayklia, orElis toOlympia. The gauge of these stone grooves was138 to144 cm (4 ft 6 in to 4 ft 9 in). The largest number of preserved stone trackways, over 150, are found onMalta.[2]
Some of these ancient stone rutways were very ambitious. Around 600 BC the citizens ofancient Corinth constructed theDiolkos, which some consider the world's first railway. The Diolkos was a hardporos 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 1.67 m (5 ft 6 in) centres.[2][3]
References going back to at least 1937 suggest that the "gauge" of ancient rutways, and the distance between the wheels ofcarts influenced the railwaystandard gauge of the modern era which is1,435 mm (4 ft 8+1⁄2 in).[4] The argument is that this is shown by the evidence of rutted roads marked bycart wheels dating from theRoman Empire.[Note 1]Snopes categorized this legend as false but commented that "... it is perhaps more fairly labelled as 'True, but for trivial and unremarkable reasons.'"[5] The historical tendency to place the wheels of horse-drawn vehicles approximately 5 feet (1,500 mm) apart probably derives from the width needed to fit acarthorse in between the shafts.[5] In addition, while road-traveling vehicles are typically measured from the outermost portions of the wheel rims (and there is someevidence that the first railroads were measured in this way as well),[citation needed] it became apparent that for vehicles travelling on rails it was better to have thewheelflanges locatedinside the rails, and thus the distance measured on the inside of the wheels (and, by extension, the inside faces of therail heads), was the important one.
On relatively level highways, the depth of the ruts due tocarbidestudded 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.
