Two Collision Contributors, One Code Violator


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. Continue reading “Two Collision Contributors, One Code Violator”

What Could the Truck Operator See? The 3D Evaluation of Surveillance Videos

Steven M. Schorr, PE, President of DJS Associates, and Laurence Penn, 3D Animations/Technical Assistant ::::



A collision occurred when a northbound pedestrian was crossing a city street and was struck by a right turning, southbound to westbound truck. The truck operator testified that the pedestrian was not visible to him as he executed the turn.
Two surveillance videos picked up portions of the movements of the vehicles prior to and at the time of the collision. A northbound facing camera showed the back of the pedestrian approaching and entering the roadway and showed the front of the left turning truck strike the pedestrian. A southbound facing camera showed the back of the left turning truck and portions of the front of the pedestrian approaching the collision area. The question that needed to be answered was, “could/should the truck driver have seen the pedestrian prior to impact?” Continue reading “What Could the Truck Operator See? The 3D Evaluation of Surveillance Videos”

Technology that Increases Pedestrian Safety at Night

Robert T. Lynch, PE, Sr. Collision Reconstruction Engineer ::::
On average, a pedestrian is killed every two hours and injured every 7 minutes in traffic crashes in the United States with an overwhelming proportion of fatal collisions occurring at night . When corrected for mileage, nighttime fatality rates in the United States average more than three times greater than daytime rates. Under dark conditions, drivers rely on artificial lighting, such as from street lights and vehicle headlights, to illuminate their path in order to identify potential hazards. Not all roadways have street lights, and with the limitations of most vehicle headlight systems, drivers often “overdrive their headlights” where, at speeds as low as 35 miles per hour, a driver may be faced with an emergency where he or she cannot perceive, react and avoid the impending collision. Continue reading “Technology that Increases Pedestrian Safety at Night”

Speed From Video… Another Masterpiece


James R. Schmidt, Jr., BSME, Sr., Collision Reconstruction Engineer ::::
As you probably know by now, DJS can analyze dash cam and still-camera surveillance videos to quantify vehicle speed (and other parameters, if necessary). Of course, the ability to evaluate is dependent on the quality of the video, as well as the presence of fixed objects or other points of reference visible in the video for use in determining distance travelled over time (i.e. speed is distance divided by time). DJS has performed this type of analysis countless times. Quite possibly, DJS has worked with you on a case in which such an analysis was performed, or you may have read some of our other prior articles wherein this topic has been discussed at length.
With a video in hand (a dash cam video in this instance): Continue reading “Speed From Video… Another Masterpiece”

Don’t Underestimate the Importance and Power of Event Data

Event Data

James R. Schmidt, Jr., BSME, Sr. Collision Reconstruction Engineer ::::
The capability of recording event data when a crash occurs is becoming more prevalent in vehicles on the road today.
Once a crash occurs, as part of the investigation process, event data should be collected from all vehicles involved that have such recording capability.
Having been collected, the data can be reviewed and analyzed by a collision reconstruction engineer, as part of his or her analysis process. And yes, you do need to be trained in order to properly interpret, analyze, and incorporate this data into a collision reconstruction.
Oftentimes, the client is interested in knowing such things as how fast a vehicle was traveling, and whether the operator applied the brakes before impact.
Take, for example, a collision involving a Ford Ranger pickup running into the rear of a motor coach. The crash took place pre-dawn, as the motor coach was starting from a stop when the traffic signal turned green. Continue reading “Don’t Underestimate the Importance and Power of Event Data”

3D Animation: Man Struck by Carrier While Opening His Driver Side Door

Hugh Borbidge, Senior Mechanical Engineer ::::
Are you a good judge of distance? Sometimes not being able to estimate how much room you have can lead to disaster.
In the following case, a man simply walked to his double parked truck and opened his driver side door to get in. At the same time a car carrier was traveling down the street towards the man. Did the man have enough room to open his door with a truck passing by? The whole thing was caught on tape but it was hard to tell how much space was available.
DJS was hired to recreate the scene so we could accurately measure what happened. We collected laser scan data, modeled vehicles and pedestrians and recreated the movement and spatial relationships based on the surveillance video. We were able to determine that had the man waited for the truck to pass, he would have been able to safely open his door and get in. Continue reading “3D Animation: Man Struck by Carrier While Opening His Driver Side Door”

Motorcycle Handlebars: More Important Than You Think!


Robert S. Kinder, Jr., BSME, Automotive / Mechanical Engineer ::::
The handlebars are a critical component when it comes to maintaining control of a motorcycle. Whether the rider is accelerating, braking, or employing techniques such as counter-steering, a properly secured handlebar is necessary to complete such tasks. If the handlebars were to come loose or detach, could you maintain control?
Yamaha has recently recalled over twenty thousand late model motorcycles due to a painting issue that can result in the loosening of the handlebars. According to the National Highway Traffic Safety Administration (NHTSA), a handlebar that is not properly secured to the motorcycle can cause a loss of control and increase the risk of a crash. The handlebars are clamped by a metal holder. It turns out that if an external force is applied to that holder, the paint can wear off over time. As the paint wears off, a space is created between the holder and mounting surface, thus reducing the clamping force on the holder. The combination of the newly created space and engine vibration can cause the holder’s stud bolts to loosen. Not only can the studs potentially loosen, the holders/handlebars can even fall off. Thread-locking material is commonly used to prevent the loosening of bolts due to vibration, however NHTSA indicated that the holder may lack adequate thread-locking material. If the bolts were to loosen or fall off, the handlebars can become detached from the rest of the motorcycle. Continue reading “Motorcycle Handlebars: More Important Than You Think!”

Sun Glare… What a difference a day makes!

James R. Schmidt, Jr., BSME, Sr. Collision Reconstruction Engineer ::::
Sun glare occurs when the sun is positioned low in the sky ahead of the direction of travel on a given roadway. It can occur in the time periods following sunrise or preceding sunset. And, it’s just what it sounds like … it’s when the sun is right in your face, thereby complicating the task of driving!

Continue reading “Sun Glare… What a difference a day makes!”

Motorcycle Collision: “I Didn’t See the Stop Sign!”

Steven M. Schorr, PE, President of DJS Associates ::::
Synopsis: A motorcycle was traveling southbound on a two-lane, two-direction roadway approaching a T-type intersection with a four-lane roadway. The motorcycle operator (plaintiff) failed to stop at the posted stop sign, and entered the four-lane roadway where he was involved in a collision with a westbound vehicle.
The motorcycle operator testified he was traveling at the posted speed limit of 35 mph as he approached the intersection; but, due to the stop sign being obstructed, perceived the traffic control at the last instant and did not have sufficient time and distance to stop prior to entering the four-lane roadway.
The plaintiff contended that tree branches obstructed the stop sign and therefore sued the State [the governing authority for the roadway], as well as the owner of the property on which the tree was located. The area of the collision was reportedly changed by the time suit was filed. The plaintiff provided no specific “hard copy” data, including photographs or measurements, to establish the obstruction or the extent of the obstruction. Continue reading “Motorcycle Collision: “I Didn’t See the Stop Sign!””