question: Especially on newly worked roads, how do potholes occur?
comment: Water is incompressible (almost.) When large vehicles drive on wet roadway the treads on the tires force the water away from the point of contact. This forces some of the water into small cracks and fissures already present in the asphalt and since water is pretty hard to compress it makes the cracks and fissures larger. Since so many people drive cars, there's a chance that this process will happen hundreds if not thousands of times a day, 24 hours a day. Asphalt is also a temperature sensitive material. When it gets hotter it expands, when it gets colder it contracts. If that happens fast enough/ enough times, it can cause cracks and potholes as well.
passages: Other failure modes include aging and surface abrasion. As years go by, the binder in a bituminous wearing course gets stiffer and less flexible. When it gets "old" enough, the surface will start losing aggregates, and macrotexture depth increases dramatically. If no maintenance action is done quickly on the wearing course, potholes will form. The freeze-thaw cycle in cold climates will dramatically accelerate pavement deterioration, once water can penetrate the surface.
   Potholes can grow to several feet in width, though they usually only develop to depths of a few inches. If they become large enough, damage to tires, wheels, and vehicle suspensions is liable to occur. Serious road accidents can occur as a direct result, especially on those roads where vehicle speeds are greater.
  
  Potholes may result from four main causes:
  
  Section::::Prevention.
  
  The following steps can be taken to avoid pothole formation in existing pavements:
  
  Section::::Prevention.:Survey of pavements.
   According to the US Army Corps of Engineers, pothole formation requires two factors to be present at the same time: water and traffic. Water weakens the soil beneath the pavement while traffic applies the loads that stress the pavement past the breaking point. Potholes form progressively from fatigue of the road surface which can lead to a precursor failure pattern known as crocodile (or alligator) cracking. Eventually, chunks of pavement between the fatigue cracks gradually work loose, and may then be plucked or forced out of the surface by continued wheel loads to create a pothole.
   BULLET::::- In higher rainfall areas, the increased camber required to drain water, and open drainage ditches at the sides of the road, often cause vehicles with a high centre of gravity, such as trucks and off-road vehicles, to overturn if they do not keep close to the crown of the road
  
  BULLET::::- Excess dust permeates door-opening rubber moulding breaking the seal
  
  BULLET::::- Lost binder in the form of road dust, when mixed with rain, will wear away the painted surfaces of vehicles
   The Federal Highway Administration (FHWA) offers an overview of best practices which includes several repair techniques; throw-and-roll, semi-permanent, spray injection, and edge seal. The FHWA suggests the best patching techniques, at times other than winter, are spray injection, throw-and-roll, semi-permanent, or edge seal procedures. In winter, the throw-and-roll technique may be the only available option. The Council for Scientific and Industrial Research in South Africa offers similar methods for the repair of potholes.
  
  Section::::Repair.:Materials.
   In areas subject to freezing and thawing, frost heaving can damage a pavement and create openings for water to enter. In the Spring, thaw of pavements accelerates this process when the thawing of upper portions of the soil structure in a pavement cannot drain past still-frozen lower layers, thus saturating the supporting soil and weakening it.
   Asphaltic patch materials consist of a binder and aggregate that come in two broad categories, hot mix and cold mix. Hot mixes are used by some agencies, they are produced at local asphalt plants. The FHWA manual cites three types of cold mixes, those produced by a local asphalt plant, either 1) using the available aggregate and binder or 2) according to specifications set by the agency that will use the mix. The third type is a proprietary cold mix, which is manufactured to an advertised standard.
  
  Section::::Repair.:Throw-and-roll repair.
   Two artists, Jim Bachor of Chicago and Baadal Nanjundaswamy of Bangalore, India, have used artwork as a commentary on potholes by placing mosaics (depicting ice cream in various manifestations) or sculpture (in the form of a crocodile) in potholes. Elsewhere, activists in Russia used painted caricatures of local officials with their mouths as potholes, to show their anger about the poor state of the roads. and in Manchester, England a graffiti artist painted images of penises around potholes, which often resulted in them being repaired within 48 hours.
  
  Section::::See also.
  
  BULLET::::- Asphalt concrete
  
  BULLET::::- Road surface
  
  Section::::External links.
   In the United Kingdom, more than half a million pot holes were reported in 2017, an increase of 44% on the 2015 figure. There are processes in place to report potholes at different levels of jurisdiction The process for claiming compensation varies by jurisdiction. 
  
  Section::::Pothole art.
   Water trapped under the pavement softens the subbase and subgrade, making the road more vulnerable to traffic loads. Water under the road freezes and expands in cold weather, causing and enlarging cracks. In spring thaw, the ground thaws from the top down, so water is trapped between the pavement above and the still-frozen soil underneath. This layer of saturated soil provides little support for the road above, leading to the formation of potholes. This is more of a problem for silty or clay soils than sandy or gravelly soils. Some jurisdictions pass frost laws to reduce the allowable weight of trucks during the spring thaw season and protect their roads.
   Section::::Definitions.:United States.
  
  In the United States, laws distinguish between "public roads", which are open to public use, and "private roads", which are privately controlled.
  
  Maintenance is becoming an increasing problem in the United States. Between 1997 and 2018, the number of existing roads too bumpy to drive on compared to roads with decent surfaces has increased by 11%, mostly due to potholes that are not being properly addressed.
  
  Section::::History.
   BULLET::::- Concentrated leak: seeping water erodes and enlarges a crack until a breach occurs. The crack may not progress to the exit (albeit failure is still possible), but eventually the continued erosion forms a pipe or a sinkhole.
  
  BULLET::::- Backward erosion: initiated at the exit point of the seepage path, this type of erosion occurs when the hydraulic gradient is sufficiently high to cause particle detachment and transport; a pipe forms backwards from the exit point until breach.
   Similar processes can act on asphalt pavements, contributing to various forms of cracking and other distresses, which, when combined with traffic and the intrusion of water, accelerate rutting, the formation of potholes, and other forms of pavement roughness.
  
  Section::::Volumetric expansion.
   Pothole
  
  A pothole is a depression in a road surface, usually asphalt pavement, where traffic has removed broken pieces of the pavement. It is usually the result of water in the underlying soil structure and traffic passing over the affected area. Water first weakens the underlying soil; traffic then fatigues and breaks the poorly supported asphalt surface in the affected area. Continued traffic action ejects both asphalt and the underlying soil material to create a hole in the pavement.
  
  Section::::Formation.
   In horizontal section potholes are roughly circular to elliptical and vary in diameter from 20 m to more than 1 km. In vertical section their shape is generally dish-like and may be quite asymmetric.
  
  Section::::See also.
  
  BULLET::::- Fault (geology)
  
  Section::::References.
  
  BULLET::::- "Predictability of Pothole Characteristics and their Spatial Distribution at Rustenburg Platinum Mine" - Chitiyo, Schweitzer, de Waal, Lambert and Ogilvie "(Journal of the Southern African Institute of Mining and Metallurgy - December 2008)"
   Pothole (disambiguation)
  
  A pothole is a surface disruption in a roadway, caused by fatigue and erosion.
  
  Pothole may also refer to:
  
  BULLET::::- A small deep hole dug to look for buried public utilities, see vacuum excavation
  
  BULLET::::- Pothole (geology), a phenomenon encountered in the platinum mining industry in South Africa
  
  BULLET::::- Pothole (landform), evorsion, swirlhole, or giant's kettle, a smooth, bowl-shaped or cylindrical hollow created by water erosion of bedrock
  
  BULLET::::- Pothole, or panhole, a shallow solution basin, or closed depression, found on flat or gently sloping rock
   Poor drainage in the road bed is a frequent cause of this degradation of the base or subgrade. A heavy spring thaw, similarly to poor drainage, can weaken the base course, leading to fatigue cracking. 
   BULLET::::- Cold in-place recycling. Bituminous pavement is ground or milled into small particles. The asphalt millings are blended with a small amount of asphalt emulsion or foamed bitumen, paved and compacted, allowed to cure for seven to ten days, then overlaid with asphalt.
   BULLET::::- An older portion of roadway being left unused by a highway realignment. The Abandoned Pennsylvania Turnpike is one instance of this, where two two-lane tunnels and four-lane approaches were bypassed with four-lane cuts. The old tunnels and approach roadways in this case are being rehabilitated for a multi-use trail. Some parts of the A1 and A3 motorways in Italy have been recently abandoned after some dangerous, curvy and narrow mountain stretches were replaced by wider and straighter alignments through new viaducts and tunnels. In many roads in the Alps, some dangerous sections were replaced by tunnels and the abandoned parts are usually closed to traffic and used as hiking trails.
   Both new and old roads often have insufficient drainage gradient at the entrance and exit of sharp outercurves, causing water pooling in rain and forming local surprising ice spots in cold climate. 
  
  A large study in Sweden (see the linked "Analysis of single vehicle accidents with fatal outcome" below) showed that fatal single crashes are 5 times more common in outercurves, than in innercurves. This extreme overrisk is considered strongly related to improper banking and insufficient drainage gradient at outercurves.
   BULLET::::- Bourke's Luck Potholes - Bourke’s Luck Potholes are a series of natural geological formations that were formed by centuries of water flowing through the landscape. The potholes occur where the Treur River joins the Blyde River at the start of the Blyde River Canyon. In a continuous manner, the force of the water in these two rivers, combined with the particles of sand and rock that the rivers' transport, wears cylindrical potholes into the sandstone bedrock.
   Likewise, macadam and tarmac pavements can still sometimes be found buried underneath asphalt concrete or Portland cement concrete pavements, but are rarely constructed today.
   In the autumn of 1967, already marked by heavy rains, the cracks in the ground expanded. During the winter of 1967-1968, the successions of freeze-thaw lubricated the sliding surfaces. The rainy spring only aggravated the instability of the land. During the autumn 1968 rains, more than a year after the start of the sequence, a flow was triggered resulting in a blackish marl-limestone detrital mass and marl-shale colluvium. 
  
  Section::::Geography.:Toponymy.
   Pothole (geology)
  
  Potholes are frequently encountered during mining operations in the Bushveld Igneous Complex in South Africa. Two orebodies, the Upper Group 2 (UG2) and the Merensky Reef, host about 70% of the world's platinum group metals (PGM), and pose major extraction problems for the mining industry in their faults, dykes, joints, domes, iron-rich ultramafic pegmatoids, rolls and dunite pipes. The greatest mining problems, though, are presented by potholes.
   BULLET::::- 'washboard' corrugations cause loss of control or damage to vehicle systems such as suspension and steering
  
  BULLET::::- Skidding (loss of traction) on mud after rain.
  
  Section::::Driving on dirt roads.:Laterite and murram roads.
  