Tag Archives: Robert T. Lynch

May is Motorcycle Safety Month

Robert T. Lynch, P.E., Principal Collision Reconstruction Engineer

As the warmer weather approaches, more and more motorcycles are hitting the streets. Coming out of the winter months, where you would rarely see a motorcycle in operation in the northern half of the country, automobile operators must retrain their brains to specifically “Watch for Motorcycles.” In particular, drivers should take an extra moment to scan the oncoming lane for motorcycles prior to executing a left turn. Intersections introduce the greatest potential for vehicular conflict, and not surprisingly, account for the overwhelming majority of motorcycle (and automobile) collisions.

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Crossing Roadways at Night

Robert T. Lynch, P.E., Principal Collision Reconstruction Engineer

It is no secret. Pedestrians crossing a roadway at night can identify the headlights of an approaching vehicle much easier than it is for a driver to observe pedestrians. However, research on drivers’ recognition distances indicates that a vehicle operator can identify a pedestrian crossing right-to-left from a greater distance than a pedestrian crossing from left-to-right. This is largely due to the requirement for low beam headlights to be angled more toward the right side of the roadway to prevent unnecessary glare for oncoming vehicle operators (SAE J1383).

To put this in perspective, a vehicle being operated at 25 miles per hour at night requires approximately 100 feet of total distance for a driver to perceive a hazard, and then react to the hazard by applying full braking to come to a stop. The nighttime recognition distance research indicates that a pedestrian wearing dark clothing crossing left-to-right is not identified by the average driver until the vehicle is less than 100 feet away, rendering the incident unavoidable for the driver. On the other hand, a pedestrian wearing dark clothing crossing from right-to-left is identified by the average driver at a distance greater than 100 feet, allowing the driver enough distance to perceive, react and avoid the pedestrian. Pedestrians in light-colored clothing or retroreflective material are observed by drivers at greater distances.

When crossing a roadway at night, the drivers approaching your location from your left can see you from a greater distance than those approaching from your right. Regardless, it is best for a pedestrian to use safe practices when crossing a roadway at night and always assume that vehicle operators cannot see you. Wait for a sufficient clearance in traffic (from both directions), or ensure that the vehicles have stopped or are stopping to allow you to cross.

Robert T. Lynch, P.E., Principal Collision Reconstruction Engineer with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

Does Wearing Yellow Glasses Improve Nighttime Visibility?

Yellow Sunglasses

Robert T. Lynch, P.E., Principal Collision Reconstruction Engineer

Despite claims that yellow glasses improve night vision, a recent study by Harvard researchers indicates that subjects wearing yellow glasses at night responded a fraction of a second slower than those not wearing the glasses.

Yellow glasses filter out blue light, which tends to get scattered more than red light due to its shorter wavelength. This scattering of blue light is said to contribute to headlight glare; so, the theory behind yellow glasses is that by filtering out the blue light, the glare is reduced, and night driving is improved. However, the white light emitted from vehicle headlights is made up of all the wavelengths of the visible spectrum, and by filtering out blue light, the total amount of light reaching the eye is reduced.

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IIHS Top Safety Rating to Include Better Headlights


Robert T. Lynch, P.E., Principal Collision Reconstruction Engineer

The Insurance Institute for Highway Safety (IIHS) has just announced that 2020 model year vehicles qualifying for the Top Safety Pick+ award need to have “good” or “acceptable” headlights as standard equipment. IIHS feels that this will encourage automakers to stop equipping vehicles with poor headlights that don’t light the road.

About half of all fatal crashes in the U.S. occur in the dark, and more than a quarter occur on unlit roads. The overwhelming majority of fatal pedestrian collisions occur at night. Headlights have an obvious role to play in preventing nighttime crashes, but not all headlights perform their job equally. Differences in bulb type, headlights technology and even the aim of the headlights all affect the amount of useful light on the roadway ahead.

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Automatic Emergency Braking Doesn’t Always Prevent Pedestrian Collisions

Breaking Technology

Robert T. Lynch, PE, Principal Collision Reconstruction Engineer

Automatic Emergency Braking (AEB) is generally designed to automatically apply the brakes when a rear-end vehicle collision is imminent. This technology has been shown to mitigate rear-end impacts; however, this technology is not always capable of detecting pedestrians crossing in front of a vehicle.

AAA has conducted testing of vehicles equipped with AEB and found that in 60% of the tests, the vehicle failed to stop, from an initial speed of 20 miles per hour, before striking the pedestrian dummy. The testing was performed during daylight hours with adult pedestrian dummies. The tested vehicle performed worse at higher speeds, under dark conditions, and with child dummies.

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The Importance of Event Data in Low Speed Collisions

Event Data Recorder

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

All model year 2013 and newer vehicles equipped with an event data recorder (EDR) that are sold in the United States need to adhere to the requirements set forth in 49 CFR Part 563 of the federal standards.

Part 563 establishes minimum requirements for an EDR. In particular, an EDR must record an event if the vehicle experiences a Delta-V (change in velocity) above 5 mph from any direction: front, rear or side. When a vehicle sees a Delta-V greater than 5 mph, the EDR will record 5 seconds of pre-crash speed, braking, and acceleration data, as well as severity data for the impact itself.

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