Tag Archives: Robert T. Lynch

Two Collision Contributors, One Code Violator


motorcycle-accident-reconstruction-expert-witness

Robert T. Lynch, PE, Senior Collision Reconstruction Engineer ::::

A motorcycle traveled across the double yellow centerline into the opposite travel lane on a rural, two-lane roadway in order to pass a farm tractor. When the tractor turned left at the intersection a collision occurred. DJS Associates was retained to evaluate the matter to determine the contributing factors that led to the subject incident. The incident would have clearly been avoided if the tractor operator hadn’t turned left or if the motorcyclist decided not to pass the tractor at the intersection. So, in general, the actions of both operators could be considered as contributory. However, a review of the (Pennsylvania) state statutes indicated that the actions of the motorcyclist were in violation of the vehicle code while the tractor operator’s actions were in compliance with the vehicle code

The vehicle code requires that a left-hand turn be completed from the left-most lane available, and that the driver of a vehicle intending to turn left at an intersection yield the right-of-way to any vehicle approaching from the opposite direction which is so close as to constitute a hazard. From an engineering perspective, the actions of the tractor operator to turn left at the intersection from the travel lane were in compliance with the vehicle code.

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Following Too Closely – Not Always as Straightforward as it May Seem


Following too close

Robert T. Lynch, PE, Senior Collision Reconstruction Engineer ::::

All states have a provision within their respective Vehicle Code pertaining to “following too closely” which states, in general, that “the driver of a motor vehicle shall not follow another vehicle more closely than is reasonable and prudent, having due regard for the speed of the vehicles and the traffic upon and the condition of the highway.”(1) Whenever a rear-end impact occurs, the investigating police officer will typically list “following too closely” as a contributing factor; however, not all drivers that rear-end another vehicle are keeping an unsafe following distance (a.k.a. headway) or are following “more closely than is reasonable and prudent” having due regard for the speed of the vehicles on the highway.

Most states recommend a 3 to 4-second “following distance rule” within their driver’s manual. This rule generally provides for sufficient distance to bring a vehicle to a stop in most driving situations; however, the rule is not conducive for drivers on congested highways where keeping such a distance would allow other vehicles to “cut in line” and effectively reduce safety by increasing the number of potential vehicular conflicts. It is often argued that the following distance rule is rarely observed in practice. Support for this argument is found in the review of the attached Google Earth™ aerial image of I-95 in Philadelphia, PA which illustrates that the majority of drivers within this image are accepting a following distance of 100 feet or less, with an average time headway (assuming the vehicle are traveling at the 55-mph speed limit) of about 1 second. A headway equivalent to 1 second is consistent with published research data on “real world” typical time headways. (2) The acceptance of a reduced headway suggests that drivers are “reading the road” assessing the state of traffic as a whole and not just focusing on the vehicle directly in front of them.

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Dukes of Hazzard Jump… In A Minivan


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Robert T. Lynch, PE, Sr. Collision Reconstruction Engineer ::::

A stake body pickup truck, towing a landscape trailer, was parked on the right shoulder of a two-lane roadway on a clear, sunny day. The lawnmowing equipment in both the bed of the truck and the trailer had been removed. There was no rear gate for the stake body, and the ramp to the trailer was down. Along came a minivan that drifted onto the shoulder of the roadway and hit the ramp square-on. Tire marks were observed on the wooden boards affixed to the sides of the trailer and stake body, showing the path the minivan took through the air. Scrape marks were also observed to the roof of the pickup truck where the underside of the minivan grazed the roof during its flight. Other than these minor markings, the pickup truck and trailer sustained no significant damage. The minivan landed in front of the pickup truck on the shoulder of the roadway, coming to rest on all four tires where it then caught fire. Fortunately, the occupants of the minivan were able to get out of the vehicle before sustaining further injury from the fire. The minivan sustained no significant crush damage.

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Paying Attention: Will an Alert Driver Avoid a Crash?


alert-driver-avoid-crash

Robert T. Lynch, PE, Senior Collision Reconstruction Engineer ::::

Possibly… but not necessarily. I recently visited the Miami, Florida area on vacation and encountered several of these signs on the highways in and around the city. The wording of the sign had me reflecting on my undergraduate logic class, literally learning about the P’s and Q’s of modus ponens (if P then Q) and modus tollens (if not Q then not P). By the rules of inference, if a statement is true, then so is its contra-positive. In other words, (if P then Q) is the same as (if not Q then not P).

Now that we all are up to speed with our P’s and Q’s, when the Miami sign is applied to the logic framework, the sign would read: if a driver is alert then a crash can be avoided. Accepting this statement as true indicates that its contra-positive is also true: if a collision occurs then the driver was not alert. While this statement makes logical sense, as drivers who are not paying attention are more susceptible to crash, not all collisions occur due to driver inattention.

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DJS Announcment


robert-lynch-accident-collision-reconstruction-expert

Robert T. Lynch, PE, Sr. Collision Reconstruction Engineer for DJS Associates, recently completed the Post-Baccalaureate Credit Certificate Program in Human Factors Engineering and Ergonomics through Penn State University. The program allowed Bob to obtain a deeper understanding of the human processes involved behind the fundamental concepts of collision reconstruction such as hazard identification and perception-reaction time. By obtaining this certificate, Bob has the educational background and knowledge to address issues pertaining to visibility, particularly at night or in low illumination environments, and how people will respond when faced with a sudden emergency. This knowledge will prove useful in cases involving pedestrian impacts, tractor-trailer side underride collisions, and encountering a slow-moving or stopped vehicle on a highway, to name a few.

Congratulations Bob!

Robert T. Lynch, PE can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

Smarter Cars, Brighter Roads


Nighttime Photography in Collision Reconstruction

Robert T. Lynch, PE, Senior Mechanical Engineer ::::

To mitigate pedestrian collisions, automobile manufacturers, such as Toyota, have started to install autonomous tech, including pedestrian detection systems and automatic high beams, as standard equipment across all models. With new high-intensity, energy-efficient street lighting technology coming down in price as well as maintenance and operational costs, more and more municipalities are adding street lights along their roadways, especially in areas with high pedestrian traffic.

Properly positioned street lighting makes a roadway safer for pedestrians, but it also presents an added challenge to the reconstructionist attempting to evaluate what the lighting conditions were at the time of the subject incident. DJS Associates was recently retained to conduct a nighttime site inspection with the hope of acquiring representative photographs to show how dark/bright the roadway was under similar conditions as the time of the subject incident. To our surprise, multiple street lights were added along the opposite side of the roadway between the incident and the inspection. The conditions were not substantially similar to those at the time of the incident, so nighttime photographs would have provided little to no benefit to the reconstruction.

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