A skid mark is the visible mark left by any solid which moves against another, and is an important aspect of

trace evidence Trace evidence occurs when objects make contact, and material is transferred. This type of evidence is usually not visible to the naked eye and requires specific tools and techniques to be located and obtained. Due to this, trace evidence is often ...

analysis in

forensic science Forensic science combines principles of law and science to investigate criminal activity. Through crime scene investigations and laboratory analysis, forensic scientists are able to link suspects to evidence. An example is determining the time and ...

and

forensic engineering Forensic engineering has been defined as "the investigation of failures—ranging from serviceability to catastrophic—which may lead to legal activity, including both civil and criminal". The forensic engineering field is very broad in terms o ...

. Skid marks caused by tires on roads occur when a vehicle wheel stops rolling and slides or spins on the surface of the road. Skid marks can be analyzed to find the maximum and minimum vehicle speed prior to an impact or incident.

Skid __NOTOC__ Skid or Skids may refer to: * Skid, a type of pallet * Glossary of bowling#Skid, the first phase of bowling ball motion, preceding the hook and roll phases * Skid (aerodynamics), an outward side-slip in an aircraft turn * Skid (automob ...

ding can also occur on

black ice Black ice, sometimes called clear ice, is a coating of glaze ice on a surface, for example on streets or on lakes. The ice itself is not black, but visually transparent, allowing the often black road below to be seen through it and light to be ...

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engine ...

deposits on the road and may not leave a mark at all.

Characteristics

Skid marks are divided into "acceleration marks" created on acceleration, if the engine provides more power than the tire can transmit; "braking marks", if the brakes "lock up" and cause the tire to slide; or " yaw marks", if the tire slides sideways. Each skid mark has a characteristic appearance, and an experienced accident reconstructor or forensic engineer can often determine what the vehicle was doing by examining the marks left by the tire. Different road surfaces produce different kinds of skid marks, sometimes also referred to as ''scuff marks'' or ''tire marks''. On asphalt road surfaces, skid marks are usually the result of bituminous oils in the asphalt that are heated because of the friction of braking or accelerating and rise to the surface, leaving dark marks.Carty, G. Collision Reconstruction. Nov 3, 2016. Mississauga, ON : University of Toronto Mississauga. This kind of mark on asphalt can last for months or even a year or two if they are particularly dark and the roadway is not well traveled. On other road surfaces, such as concrete, the marks result from the deposition of tire compounds onto the surface of the roadway. This kind of skid mark is typical of airport runways, which need to be periodically cleaned to remove deposited debris that reduce the frictional coefficient of the runway.D.P. Eisenbeisz, Wikipedia Talk response. June 28, 2008.Miranda, M. Tire Marks & Their Role in Accident-Reconstruction Investigations. Jan 8, 2018. PInow.com. The durability of these marks depends on a number of factors, including road use, tire compounds, weather, and frequency of road cleaning. Braking marks will vary depending on whether the car uses ABS or not. If not, there will be two lines. The darker marks on the outside are from the front wheels, while the back tires leave thinner marks. This is because the force exerted makes the wheels take on a conical shape. If the car uses ABS, the marks will be much fainter as less heat is produced by the release-stop mechanism of ABS. Scuff marks may be visible however with ABS. The term "scuff mark" is more often used for marks left by rubber

shoe A shoe is an item of footwear intended to protect and comfort the human foot. Though the human foot can adapt to varied terrains and climate conditions, it is vulnerable, and shoes provide protection. Form was originally tied to function, but ...

s on a floor, mainly sneakers or trainers leaving black rubber marks on a

gym A gym, short for gymnasium (: gymnasiums or gymnasia), is an indoor venue for exercise and sports. The word is derived from the ancient Greek term " gymnasion". They are commonly found in athletic and fitness centres, and as activity and learn ...

nasium floor or

basketball court In basketball, the basketball court is the playing surface, consisting of a rectangular floor, with baskets at each end. Indoor basketball courts are almost always made of polished wood, usually maple, with -high rims on each basket. Outdoor ...

when someone comes to a hard stop, or pivots in place, or a

hockey puck A hockey puck is either an open or closed disk used in a variety of sports and games. There are designs made for use on an ice surface, such as in ice hockey, and others for the different variants of floor hockey which includes the wheeled skat ...

leaving a rubber streak along the edge boards of the rink.

Ladder accidents

Skid marks can also be formed where a ladder suddenly slips and the user falls to the ground, especially if the ladder feet are faulty or absent. Loss of the

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...

feet or foot causes the

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

stile to make contact with the ground, and if a hard surface like concrete or tiling, a skid mark shows how and why the ladder slipped. Unless fixed to the wall upon which they are leaning, ladders can slip down easily, especially if the ladder is leaned at an angle lower than about 75 degrees. Such slip accidents tend to happen when the user is near the top of the ladder, increasing his or her chances of serious

personal injury Personal injury is a legal term for an Injury (law), injury to the body, mind, or emotions, as opposed to an injury to property. In common law, common law jurisdictions the term is most commonly used to refer to a type of tort lawsuit in which the ...

Accident reconstruction

Such marks are important evidence for

vehicular accident reconstruction Traffic collision reconstruction is the process of investigating, analyzing, and drawing conclusions about the causes and events during a vehicle collision. Reconstructionists conduct collision analysis and reconstruction to identify the cause o ...

, when their size and shape can reveal much about vehicle speed and forces of acceleration or deceleration. They are one form of

. They represent a form of contact evidence produced according to

Locard's exchange principle In forensic science, Locard's principle holds that the perpetrator of a crime will bring something into the crime scene and leave with something from it, and that both can be used as forensic evidence. Dr. Edmond Locard (1877–1966) was a pione ...

. The length of the skid mark is usually closely related to the vehicle speed at the instant of braking, so measuring the marks yields an estimate of original speed.

Modern slang

In modern

slang A slang is a vocabulary (words, phrases, and linguistic usages) of an informal register, common in everyday conversation but avoided in formal writing and speech. It also often refers to the language exclusively used by the members of pa ...

, the term "skid mark" means a

fecal Feces (also known as faeces or fæces; : faex) are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relatively small amount of ...

stain or smear on the back of one's

underwear Underwear, underclothing, or undergarments are items of clothing worn beneath outer clothes, usually in direct contact with the skin, although they may comprise more than a single layer. They serve to keep outer clothing from being soiled ...

. It may also apply to a pet experiencing anal irritation and sliding (or scooting) across the floor to relieve the itching or obstruction, leaving a line of feces behind.

Notes

References

External links

Accreditation Commission for Traffic Accident Reconstruction (ACTAR)

National Highway Traffic Safety Administration

National Academy of Forensic Engineers
{{Tires, state=collapsed Tires Evidence law Forensic evidence