Paying Attention: Will an Alert Driver Avoid a 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. Continue reading “Paying Attention: Will an Alert Driver Avoid a Crash?”

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”

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”

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”

Evaluating Motorcycle Skid Marks

Motorcycle Accident Reconstruction

Robert T. Lynch, PE, Senior Collision Reconstruction Engineer ::::
When a motorcycle leaves a skid mark leading up to a collision, it is indicative of hard braking applied by the rider prior to impact. The skid mark can be from either a locked front or rear tire, or both, as the rear tire follows the same path as the front, laying one skid mark on top of the other. It is not always obvious from the skid mark deposited on the roadway whether both wheels are locked or only one wheel was locked to create the skid mark. An evaluation of the motorcycle tires could potentially determine if both or only one tire was locked. For instances, where there is evidence of only the rear wheel being locked to create the skid mark, one must not assume that only the rear brake was applied. This assumption leads to a reduced roadway friction coefficient, and subsequently, an artificially low speed of the motorcycle.
Even though the evidence may only indicate that the rear wheel was locked during the pre-impact phase of the collision, the absence of a front tire skid mark does not preclude the possibility that the front wheel was also braked, just not enough to lock the wheel to leave a skid mark. As a rider myself, I know that a locked front wheel is something to avoid, but a locked rear wheel is okay as long as the motorcycle is upright, and traveling along a straight path. The Pennsylvania Motorcycle Operator’s Manual states, “If the front wheel locks, release the front brake immediately then reapply it firmly.” The front brake lever should be squeezed firmly and progressively as the front brake can provide 70% or more of the potential stopping power. Continue reading “Evaluating Motorcycle Skid Marks”

Headlights: An Overlooked Safety Feature?

Robert T. Lynch, PE, Senior Mechanical Engineer ::::
With today’s vehicles boasting new safety technology such as blind spot detection, autonomous emergency braking, and lane keep assist, headlight performance is often an overlooked safety feature only considered as an afterthought once the vehicle leaves the sales lot. For a technology that has existed (and been improved upon) for over a century, the average car buyer has undoubtedly developed a false sense of security when it comes to new vehicle headlights expecting the lighting technology to be state-of-the-art and provide sufficient illumination to light up the roadway at night.
However, recent testing by the Insurance Institute for Highway Safety (IIHS) has revealed that the headlights on many new vehicles do not provide enough light for a driver going 55 miles per hour on a straight road at night to stop in time after spotting an obstacle in his or her lane. Of the 269 headlight systems (Halogen, High-Intensity Discharge, LED) tested in 129 model year 2017 vehicles, more than half were rated marginal or poor. And buying an expensive vehicle, which is often associated with better safety performance, does not guarantee decent headlights. For the mid-sized SUV market, the Hyundai Santa Fe received a good rating while the Infinity QX60, with a base price of nearly $15,000 more than the Hyundai, received a poor rating. Continue reading “Headlights: An Overlooked Safety Feature?”

“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…””

Watch For Motorcycles… And Riders Watch The Road

Robert T. Lynch, PE, Sr. Collision Reconstruction Engineer ::::
This spring we have experienced some unseasonably warm weather, already breaking 80 degrees a couple days during the month of April here in the Philadelphia area. If you’re anything like me, owner of a motorcycle and a pulse, you’ve been itching for warmer weather for the past 4 months in order to reacquaint your bike to the curves of your favorite back roads.
But before you grab your gear, kick the tires, and saddle up, just take a moment to recall how different, and mentally taxing, it can be to ride a motorcycle, specifically how to handle turns on a motorcycle as opposed to a vehicle. A motorcycle is leaned left or right to turn and not steered, which reduces traction potentially creating a slippery situation. Traveling around a curve with loose gravel in the roadway is one of the biggest hazards that a rider will face over the next month or so as the remnants of salt, sand and loose gravel deposited on the roadway during the winter season still remain. Continue reading “Watch For Motorcycles… And Riders Watch The Road”

Not all “Black Boxes” are Created Equal, Until Now…

Black Boxes

Robert T. Lynch, PE, Sr. Collision Reconstruction Engineer ::::
Nearly all vehicles sold in the US since 2013 have an event data recorder (EDR), more commonly known as a black box, which is capable of recording data in non-trivial crashes. A non-trivial crash, as defined by 49 CFR Part 563 – Event Data Recorders, is any collision resulting in a change in velocity (Delta-V) to the vehicle of more than 5 miles per hour over 150 milliseconds. Older vehicles with EDRs would typically only record data in frontal collisions, but the current regulation for vehicles requires EDRs in newer vehicles to record data in front, side and rear impacts greater than 5 miles per hour Delta-V.
If a vehicle is compliant with Part 563 (vehicles 2013 and newer) and is involved in a crash resulting in a Delta-V above 5 miles per hour, 5 seconds of pre-impact speed, acceleration and braking data will be recorded in the EDR. While this information is often valuable to reconstruct the collision, the absence of data stored in the EDR can be equally as beneficial to the reconstruction.
Continue reading “Not all “Black Boxes” are Created Equal, Until Now…”