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.

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MANAGEMENT scene ©

Research and Management of the scene in a car accident rather complex depending on the magnitude of the accident and different items of evidence and physical evidence found in it.

Upon arrival at the scene, we must pay close attention to the verification and confirmation of the fact, determining whether there had only damage or casualties to determine its severity and proceeding with care first aid, among others.

Once evacuated the victim, we will protect the scene and take note of the people involved in the accident, as well as drivers and witnesses. As a foremost authority on the scene should make an observation of the items of evidence and physical evidence and the relevant minutes will be made which will record the observed.

First of all we must determine if the scene there is a traffic accident, sports, labor, among others ... It is important to take into account the definition of accident as an event that has generated at least one moving vehicle and as a result have damage, injury or death. Likewise, the vehicle is any device mounted on wheels, traction motor, animal or human drive, excluding wheelchairs, skates, skateboards and the like, promptly let the Law 769 of 2002 National Traffic Code.

Once the accident, we will continue with the analysis of impacts under the different masses, to determine if your class is a collision, overturning, collision, collision with fixed object, occupant crash, fire, other . In the form filled out by the traffic authorities in the scene, always mark the first impact, and kinds of accidents produced after this, will be made by way of observations of a dynamic description of the accident.

Following our actions as a first responder at the scene, we will post the same descriptively, take photographic records and to fasten planimetric measurement using the method that best fits the site and its ease, as a method of Cartesian coordinates, triangulation or angular coordinates, among others.

The Cartesian method is the measurement of a point with respect to a baseline (X axis) at an angle 90 degrees and then to a point of reference which will house the Y-Axis The reference point in the intersection must be the extension of the way (Esquinas) taking wide distance from roads, c arriles and platforms and sidewalks. In the case of track sections in urban area is used as a reference point the edge of buildings, in their absence, shall be to a street light pole or telephone lines. In rural areas will be made to the posts of mileage.

The triangulation method measures distances from point or item of evidence with respect to two reference points (eg, two light poles pub) determining the distance between these two points. This method is not determined angles, only distances that indicate the radius of two circles that at the time of the scale plan for union of the two circles we find the fixed point in the scene.

The angular coordinates method, determine the distance and angle between the element and the reference point, counting as a baseline the direction of North.

elements to set planimetric and photographers in the scene are:

• Vehicles and their footprints in the road surface. The measurement of the vehicles to the baseline, can be made from the same points or axes, the important thing is that then are taken wheelbase and front and rear flown each vehicle or its width. Similarly the distortions.
• Glass and debris from liquids ... From the center of focus.
• final position of the Victims.
• width and length of the different tracks give the road, checked with the tires have left their mark.

For curved tracks, the length is measured above the formed the same curvature imprint. For the plane, it should consider a measure from the beginning and end of the track in a straight line (rope) and center line will be taken away from the rope to the footprint (or ordered Sagita average) with to find the radius of the curve. The same method is used for the radius of curvature of the road.

• If the path is curved, and to determine its radius, we analyze the percentage of cannot.
• The percentage of cannot is determined using the same formula to calculate the percent of the slope of the track, extending the measuring tape horizontally on the track without touching the road surface (only the zero point tape) to maintain its position with a hand level with the distance you. want. Later take the distance between the tape and the high road surface. the formula is vertical to the horizontal, multiplied by 100%.
  

Note that setting the vehicle tracks and the victims will always have four measures of different lengths.

Once planimetric and photographic setting, check the horizontal and vertical signaling the way, if passive safety features, distances between the signaling devices, lights, signals work etc. Determine the road design and features, materials and road surface condition.

With all the items of evidence found at the scene, conduct an analysis relating place and point of impact, location of the mass at impact according to their deformation (distance and height), and together with the final position adopted by them, identify the trajectories of the masses before impact, determine direction of travel and the lane circulating.

With respect to deformations, state of the road surface, mass difference and footprints in the road, it is important to determine the approximate speed at which the vehicle was traveling.

natural formula used to determine the velocity is:

The speed is equal to 15.9 by the square root of: coefficient of friction (according to the road surface and wheels of the vehicle) the distance Skidmark. Formula in the book of Ribers, Traffic Accident Investigator's Handbook.


To determine the coefficient of friction or friction of the road, use: Cr = Velocity squared on 254 by braking distance.

Identify the root causes of the accident, carefully consider all the data collected and make assumptions. How and why it was presented. DO NOT place responsibilities, just causes.

All accidents are different, not in all cases so easy to determine speeds, other operations are needed to determine that we are in front of skid marks and not of paths marked by heavy vehicles, etc.

DESCRIBED ABOVE IS THE CORE CAN MAKE IN AN ACCIDENT. There is always more .....

not forget that in most traffic accidents in the scene there is a catch in the act, in accordance with paragraph 3 of Article 301 of Act 906 of 2004 Criminal Procedure Code, and the first respondent is who should make available to the competent authority when caught, who will be free or be given security measure determined in accordance with the judicial authority according to the procedure described in Article 302 of the same Act