Misprinted State Quarters

FOOTPRINTS IN THE ROAD ©

Ide ntificar the footprints of the vehicles on a road surface is a very important point during data collection in the scene where there has been a traffic accident, since the traces provide information useful for analysis of the accident determining hit points, trajectories pre-and post-impact speeds, etc.. Therefore, it is necessary recorded during data collection and diagrams, sketches or drawings, all possible information of the tracks and their characteristics, the tire or element corresponding to each trace, length, trajectory, properly related width between the tread and the tread of the tire brand.

Skidmark : Identifies the lock of the rim as deceleration maneuver emergency on a surface, on which has a maximum adhesion and resistance to longitudinal displacement.

braking footprint is caused by blocking the wheels, causing the tires to make permanent contact in the same area of \u200b\u200bthe tread, forming the energy virtually kinetic during braking is transformed into work becomes heat in areas of the tire and road surface.

This localized heating causes a significant increase in the temperature in the area, reaching to soften the rubber compound tire, and to the abrasion that is subject of the particles emerge, deposited on the pavement. Such deposit as the energy continues to transferred is sufficient to produce the phenomenon described above, thus marking the so-called skid marks.

The scene is important to differentiate whether the marked track on the road surface was produced by a tire during normal operation (normal pressure, lower then Max, etc.) or, conversely, are the hallmark of a defective tire, damaged or in poor operating conditions (overload, etc.).

UNIFORM NO TRACES

can be found ar uneven skid marks on the track, due to different reasons, for example, when the tire deformations or failure, of which include:

High Inflation Pressure: High pressure in the inflated tire generates a round (ball shaped) in the central part of the tread which is in contact with the road surface, creating clean and wear in this area of \u200b\u200bthe rim, being consistent with the marking of the trail braking, presenting a smaller width marking for a tire with pressure Correct air.

Inflation Pressure grade: A normally low inflation pressure, causes vertical forces supported by a wheel falling on the outer edges of the tread touching the road surface by the effect of stiffness Housing in flanks and shoulders. In this case the trace of braking submit a score of outdoor areas, generating two lines.

Intermittent Traces: This type of tracks are presented when the vehicle locks its wheels and suspension is highly unstable. Likewise, when the road surface is corrugated or bumpy. Also, the rear wheels of the trailers make their mark cu intermittent load'm little or is completely empty.

Metal Steal Drag : this kind of footprints are caused by the structure of a vehicle or object thereof to perform metal friction or friction with the road surface, forming several lines and in some cases cracks.

Steal Drag Tire: are produced by the wheels of a vehicle which changes its trajectory when applied an external force product structure of an impact. In your drawing you can see horizontal or diagonal lines in the direction of impact.

Steal Drift: Footprints marked by the tires of a vehicle which moves laterally as a result of wheel lock the rear axle or, if there is oil or wet road surface. Just drag the tire footprint, you can not see the picture of the tread by the various oblique lines are presented, as well as its width can vary. In this type of track is important to analyze whether the time of lateral shift, the car had blocked the wheels turning or ending or starting with a trace of braking.

Career Steal: produced by a wheel without blocking, appreciable on soft surfaces such as dirt, mud, gravel, etc., or surfaces that deform the overtaking of a vehicle, leaving marked the picture of the tread. Also you can see on hard surfaces as long as there moisture between the two surfaces.

Steal Acceleration: footprint that is caused by slippage of the vehicle tire traction on surfaces with high adhesive strength, showing in some cases, remnants of cultivars released in the opposite direction to march the vehicle. These tracks will be marked only by the drive wheels.

Footprint critical speed path: occurs when a vehicle turns a corner and the rate exceeds the limits set for the design of the road because of the different forces acting on the mass, in these cases affecting the lateral force (centrifugal force). The weight of the vehicle is moved on the outer rims the curve marking a drawing from the center of the tread to the outer shoulder of the tire, in some cases there shall be a thin line curve, depending on the speed of income or maneuver.

Skidmark. Road accident rates and Expertise. Irureta. Ed La Roca , third edition.

and road wheels. Traffic Accident Investigation. La Toma Data. Daniel A. Mantaras, Pablo Luque, Juan M. González. ED., Thomson. 2005.