【正文】 k slower than men and those under 50 years of age have a walking speed of feet per second, women over 50 walk at about fps. According to Eubanks, women with small children walk at about feet per second. He remends continued testing and observation of pedestrian behavior under various circumstances.A 1989 paper by . Ashton included results of research performed in the United Kingdom in 1965, presented here as TableV. The results of this testing is very similar to those presented in the earlier table.Pedestrian impact orientationAnother critical issue to be determined and researched on every pedestrian collision is that of pedestrian impact kinematics, or how the pedestrian moved at and through the impact phase of the collision event. Ravani classified the different pedestrian impact orientations into five distinctive groups (wrap, forward projection, fender vault, roof vault,somersault). These five distinctive styles of pedestrian kinematics have bee defacto standards when describing impact dynamics. Understanding these impact orientations in relation to the vehicle position helps the investigator in determining how injury causation occurred.In the wrap trajectory, the pedestrian is struck in the lower legs by the front of a decelerating vehicle. The striking portion of the vehicle must be lower than the height of the pedestrian. Upon impact the legs buckle and the torso bends over the hood and the chest impacts the top of the hood. The head impacts the hood in a whipping motion. After initial impact, the pedestrian tends to stay on the hood of the car and rides to a stop, sometimes sliding off the hood at stop.The next impact orientation is the forward projection. In this configuration the pedestrian is struck by a flat faced vehicle, such as a truck or van, and the force applied is well above the center of gravity of the pedestrian. This can also occurred when passenger vehicles strike small children. The pedestrian is quickly accelerated to the speed of the striking vehicle and then drops to the roadway surface ahead of thevehicle . The fender vault involves pedestrians struck near a front corner of the vehicle. First contact is usually made at the legs, with the torso pivoting towards the hood. Due to the position of the pedestrian (near the vehicle39。s edge) he falls off the edge and does not impact the hood, striking the roadway. The pedestrians head may or may not impact the vehicle. The fourth impact orientation is the roof vault, which begins initially like a wrap trajectory but in this case the pedestrian39。s legs do not stay ahead of the vehicle. Due to the impact forces the legs continue to rotate upward, with the pedestrian essentially standing on his head on or near the roof line. The vault maneuver is pleted when the pedestrian leaves the vehicle, over the roof, and tumbles to the ground. The last impact orientation is the somersault, which is similar in its initiation to the roof vault. During a somersault the vehicle is typically decelerating at impact and this causes the pedestrian to be thrown ahead of the vehicle. One would expect serious or even fatal head injuries as a result of this impact type. The impact orientations discussed here are applicable primarily to adult pedestrians. They may not always be applicable to small children due to their height.Impact speedsThe subject of impact speeds is one of mon importance to investigators of pedestrian collisions, particularly with those personnel tasked with determining violations of the law. Estimating vehicle speeds, as it relates to negligence and civil liability, is also crucial in civil are a number of different approaches to the speed question when dealing with pedestrian impacts. Ashton presented the various available techniques in descending order of accuracy, although the order can certainly be subject to interpretation:1. Skid Mmarks。2. Pedestrian Throw Ddistance。3. Vehicle Damage。4. Pedestrian Injury。5. Witness/Ddriver Sstatements.From skid marksThe easiest and most monly used method for determining the speed of a vehicle striking a pedestrian is by using skid marks. of course, this presumes the striking vehicle was braking and the total distance the vehicle skidded to a stop can be estimated. There will be some speed loss as a result of the impact with the pedestrian but this is an insignificant loss, around 12 miles per hour in most cases due the large difference in mass between the vehicle and pedestrian. The standard dissipation of energy equation, in one of its various forms, can be used to determine the vehicle39。s initial speed:From pedestrian throw distanceThe second best alternative to the speed question is by using the pedestrian39。s total throw distance to estimate an impact speed for the striking vehicle. Many times striking vehicles do not brake and throw distance is the only available evidence to estimate impact speed. When a pedestrian is struck by a moving vehicle he is accelerated in the direction of the velocity vector of the striking vehicle. The distance that the body is thrown forwards is an indicator of the speed of the vehicle at impact.A simple and better known approach to estimate impact speed of the striking vehicle is to use the sliding distance the pedestrian body skidded to a stop (not throw distance) and apply an energy dissipation equation. This is an easily defended approach but the investigator must determine the first impact point: Where: S=pedestrian speed after impact,mph d=sliding distance of body f=coefficient of friction for sliding body This method is a safe tactic to use when the pedestrian39。s first impact point along the roadway can be established, as the speed calculated will logically represent only a fraction of the vehicle39。s impact speed, that is, it will be on the low side. Some of the earliest work along the lines of calcu