Collision Reconstruction – A Desktop Analysis Approach

Robert T. Lynch, PE, Senior Collision Reconstruction Engineer ::::
Some cases don’t reach our desk until months or even years after the incident and the physical evidence that is created immediately after the collision is, at times, long gone. Any potential roadway evidence such as tire marks or gouge marks may have vanished, or the road has been repaved and the vehicles may have been repaired, or totaled, and sent to a salvage yard without a trace.
For these instances, vehicle and/or site inspections may not be feasible, or they would not be expected to provide any data that would be substantial to the reconstruction. That is, an inspection of a repaired vehicle would not be as useful as photographs displaying the damage from the collision, and although an inspection of a resurfaced site would provide roadway widths and other measurements, no roadway evidence would be expected to remain after such a long period of time. Continue reading “Collision Reconstruction – A Desktop Analysis Approach”

California to Allow Testing of True “Driverless Cars” on Public Streets by Summer 2018

Robert T. Lynch, PE, Sr. Collision Reconstruction Engineer ::::
Currently, regulation of autonomous vehicle (AV) testing and operation on public roadways in California, and most other states, requires a “safety driver” to be behind the wheel to take control of the vehicle in the event of an emergency. A proposed new set of rules, to take effect next year, will allow for testing of fully autonomous vehicles on the road without needing a safety driver. While a necessary step towards a world where autonomous vehicles are projected to be commonplace within the next couple of decades, this is a big win for the AV community as the technology rapidly advances towards a state of full autonomy.
Since 2012, California has enacted regulations pertaining to self-driving vehicles and technology. The state plays a big role when it comes to regulating the technology, as it is where a lot of the AV research and development is occurring. Currently, there are 42 auto manufacturers and technology companies testing 285 self-driving cars throughout the state. Other states are expected to follow California’s lead, as they have with prior regulations of AVs. Continue reading “California to Allow Testing of True “Driverless Cars” on Public Streets by Summer 2018”

“My Maserati does one-eighty-five…”

Robert T. Lynch, PE, Sr. Collision Reconstruction Engineer ::::
We’ve all experienced it – you’re driving on the highway minding your own business, when a vehicle surprises you as it suddenly passes you at a high speed. Your first reaction (after your heart stops racing from the initial shock) is to look to see if there is a police officer around to pull the driver over for speeding. Your second thought is… wondering just how fast the vehicle was going. Well, wonder no more. I’m going to outline a simple approach for you, rooted in basic physics, that allows you to reasonably estimate the speed of the vehicle. I know some of you get apprehensive when you read the word “physics,” but don’t be afraid, as this process works for even the non-engineer.
Here’s what you do… as soon as the vehicle passes your vehicle, start counting to 10, as if you’re playing hide-and-go-seek, counting the numbers out as seconds. When you get to 10, note the location of the speeding vehicle ahead of you. Roadside poles or painted white dashed lines on the roadway provide good visual cues in order to determine how far ahead the speeding vehicle has traveled in the 10 seconds since it passed you. We’ll call this the “10-second location.” Now, without stopping your rhythm of counting, continue on to 11… 12… 13 seconds… until your vehicle has now reached the same location where the speeding vehicle was after 10 seconds. If it takes you 13 seconds to cover the same distance that it took the speeding vehicle to cover in 10 seconds, the speeding vehicle is going approximately 30% faster than you; 14 seconds equates to 40% faster and 15 seconds equates to 50% faster. As an example, if you are traveling at 60 miles per hour and you count to 14 seconds when you reach the “10-second location,” the speeding vehicle was traveling 40% faster, or at a speed of approximately 84 miles per hour! Continue reading ““My Maserati does one-eighty-five…””

What Direction Was the Vehicle Traveling – An Analysis of an Intersectional Collision

Steven M. Schorr, PE, President, DJS Associates, Lead Collision Reconstruction Engineer ::::
A collision occurred, at a stop controlled intersection, between the front of a motorcycle and the driver (left) side of a passenger vehicle. The police took photographs of the point of rest of the vehicles and of the damage to the vehicles. Simple enough, right? Well, not so fast. When the police interviewed the involved parties, the operator of the passenger vehicle said she was northbound on the two lane, two direction roadway and was turning left to head westbound onto a one-way street when the northbound motorcycle, traveling in the same direction she was traveling, came up on her left side in the opposite lane trying to pass her. The motorcycle struck her driver side door as she was turning. The motorcycle operator informed the police that he was indeed northbound; however, as he approached the intersection, the passenger vehicle entered the intersection from his right, traveling westbound on the one-way street. As the passenger vehicle entered the intersection, it “cut him off” resulting in his motorcycle contacting the driver side of the passenger vehicle. Continue reading “What Direction Was the Vehicle Traveling – An Analysis of an Intersectional Collision”

Watch Where You Walk in A Construction Work Zone


Lt. Col. Bryan Smith, Construction Site Safety Consultant ::::
Case Summary: A dump truck, which exited a construction zone after delivering a load of asphalt paving material, struck and killed a pedestrian. The construction firm that performed the parking lot repairs hired an expert to evaluate the incident location and determine if it was within a work zone and if so, whether certain motor vehicle/pedestrian precautions were necessary and/or enacted by the construction firm.
Expert Analysis: An evaluation of the incident location was made using Google Earth satellite photos. The Google Earth photos documented what work had been performed at the time of the incident, about one year and nine months earlier from the engagement of an expert.
Continue reading “Watch Where You Walk in A Construction Work Zone”

Watch Where You Stand

Off-Tracking of Right Turning Tractor-Trailer

Steven M. Schorr, P.E., President of DJS Associates ::::
A tractor-trailer operator was executing a right-hand turn at a four-way intersection in a major city. As he was completing his turn and heading straight down the roadway onto which he turned, he was flagged down by a person who advised him that his truck contacted a pedestrian.
The physical evidence indicated that indeed the right side of his trailer did contact the pedestrian and knocked him down whereupon the pedestrian was run over by the right rear trailer tires of the right-turning tractor-trailer.
These dynamics are consistent with the properties of a right (or left) turning tractor-trailer wherein the tractor pulls the trailer. The trailer itself has no steering therefore as a result, in a right-hand turn, the right rear tires of the trailer will always track to the inside of the path of the right front tires of the tractor. This concept is referred to as “off-tracking”. The longer the trailer, the further to the inside (of the front tractor tires) the rear trailer tires will “off-track”. Continue reading “Watch Where You Stand”

Video Reveals What Really Happened with Tractor-Trailer / Pedestrian Accident

Truck Pedestrian Accident

Steven M. Schorr, P.E., President of DJS Associates ::::
Increasingly, the data available to review as part of a collision reconstruction includes video, sometimes obtained from nearby surveillance cameras, and sometimes acquired from the vehicles themselves.
Many commercial vehicles are equipped with event data recorders in the form of a camera that captures different views as the vehicle proceeds along. Depending on the equipment, the data is either recorded continuously, or the camera is manually activated by the operator, or recording is activated by a defined sudden deceleration threshold.
Recently, we were provided with a video from a truck which showed a passenger vehicle on the right shoulder with its flashers on and its hood up. The daytime video showed a pedestrian suddenly emerge from behind the raised hood of the vehicle on the shoulder, and moved directly into the path of the approaching truck. The pedestrian was struck by the right front/center of the truck. Although the conclusion as to how the collision occurred seemed obvious, we were tasked with evaluating the event from a collision reconstruction perspective, i.e., what were the factors that led to this event and, in this case, were there any additional causal factors other than the actions of the pedestrian. Continue reading “Video Reveals What Really Happened with Tractor-Trailer / Pedestrian Accident”