Expertly Speaking


Sunglare … Where?

James R. Schmidt, Jr., BSME, Sr. Collision Reconstruction Engineer ::::

This is one of the times of year where motorists are regularly encountering sun glare. The sun is low in the eastern sky during morning rush hour. The sun is low in the western sky during evening rush hour.

Take this morning, for example. I was on my ride to work, and voila … sun glare!

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BMW logo

BMW HVAC Blower Wiring Recall

R. Scott King, BSME, Sr. Automotive / Mechanical Engineer ::::

Earlier this month, BMW announced it is recalling over 600,000 3-Series vehicles manufactured between 2006 and 2011 over concerns of potential fire risk. According to documents filed with NHTSA, BMW initiated this recall upon learning of a September 2017 incident involving a vehicle fire it deemed related to the heater and air-conditioning fan wiring. The defect, according to BMW, is the result of microscopic wear, or “fretting”, between the mating components of the electrical connectors. Over time, and with continued wear, electrical resistance between the mated connector halves can increase, resulting in excessive electrical current passing through the connector, which in-turn leads to excess heat. This heat first melts the plastic encasing the connectors, then in the extreme case, ignites it.

Notable in the NHTSA filings, however, is the investigative chronology associated with this recall. As those records show, BMW first became aware of this potential fire risk as early as a decade ago. Specifically, BMW investigated two incidents, one occurring in late 2007 and another in 2008, both “involving heat related damage to the heating and cooling system”. At the time, no root-cause of the damage was identified. Then, between 2010 and 2011, more incidents were reported and investigated. This time however, BMW concluded the root-cause was related to deterioration (fretting) within the electrical connections in the fan wiring. This finding led BMW to change to the metallurgical properties of the wiring connectors; however, the change was implemented in new vehicles only beginning in 2012; no modifications to the existing vehicle population were offered. BMW also indicates that between 2007 and 2014, it had received no reports of injuries related to this concern; however, in 2015, it learned of three such incidents.

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The words Autonomous Vehicles on an automobile gauge with the needle rising past Driver Assist to reach Self-Driving to illustrate the coming of new cars that drive themselves

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.

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Empty safety seat for baby in car

Child Seat Cold Weather Safety

John R. Yannaccone, PE, Senior Mechanical Engineer ::::

As the weather starts to turn cooler, the need to add layers to keep warm begins. However, everyone needs to make sure the added layers do not compromise safety. This is especially true when it comes to children who are in child seats. While we all want our children to stay warm during a car ride, we need to be sure we are doing it in a safe way.

One of the major problems seen is dressing children in bulky or puffy coats. As the general rule, bulky coats should not be worn under the harness of a child seat. These coats prevent the harness from being tightened to the child’s body and compromise the safety of the child seat by reducing the effectiveness of the harness.

Frequently, the next question people ask is, “How do I know if my child’s coat is too bulky?”
There is a simple test you can perform to see if your child’s coat is bulky, and will cause the harness to be less effective. Start by putting your child’s coat on them, place them in their child seat, and tighten the harness. A properly tightened harness is one that you cannot pinch the harness webbing between your fingers.

Next, without loosening the harness adjustor(s), unbuckle the harness and take your child out of the child seat. Take your child’s coat off and place them back into the child seat and buckle the harness without adjusting the straps. Try and pinch the webbing as you did before. Is there more slack than there was when your child had their coat on? If so, the coat is too bulky to wear under the harness. The slack you see is what would be seen in a crash when the puffiness of the coat is compressed by the forces of the crash, and would reduce how well the harness restrains your child.

So how do you keep your child warm in the car if they have a coat that is too bulky to wear under the harness? Following are some options:

  • See if you can find a less bulky coat, i.e. a thinner fabric like an insulated sweatshirt or fleece coat which can provide warmth without bulk.
  • Have your child remove their bulky jacket before they get in the child seat. After harnessing them in, cover them with a blanket. This is a good method if you are using a carrier style child seat since you can harness the child in and cover them with a blanket before going outside.
  • Rather than a blanket, you can also place the child’s coat on them backwards after they are harnessed into the child seat. In this case, the coat serves as a blanket with arms.

Remember, no matter which of these options you choose, harnessing a child too loosely in their child seat is one of the most common errors made. Leaving slack in the harness will increase the movement of a child in a crash, and can even allow them to be ejected from the child seat. You still need to tighten the harness so you cannot pinch the webbing. Taking these steps will help keep your children warm and safe during your travels in colder weather.

John R. Yannaccone, PE, Senior Mechanical Engineer with DJS Associates Inc., can be reached via email at or via phone at 215-659-2010.

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Automotive Infotainment & Telematics: What’s Their Purpose & How do They Differ?

Robert S. Kinder, Jr., BSME, Automotive / Mechanical Engineer ::::

In the automotive industry, vehicle technology continues to advance to satisfy consumer driven functions. Whether the expectation is increased safety, comfort, or options, in-car technology demands are on the rise. One of the measures taken by automakers to mitigate these demands is the implementation of state-of-the-art infotainment or telematics systems. Although there is some overlap between these two systems, such as sharing the same visual display monitor, there are functional differences. The basis of infotainment involves the combination of entertainment and information, which may be obvious given the name “infotainment”. Common infotainment functions include GPS navigation, listening to music, and Bluetooth phone operations. More recently, infotainment systems have gained the ability to store cell phone related data when tethered by USB or Bluetooth. Infotainment systems also allow drivers to link their phones through integration software such as Apple CarPlay and Android Auto.

Vehicle telematics merge telecommunication and informatic functions. When comparing telematics and infotainment, the most notable difference is that telematics utilize two-way communication. The communication provides a platform to send and receive data. The exchange of data is necessary for features like vehicle location for navigation, collision reporting for police or insurance providers, and remote vehicle diagnostics. Telematic systems can be built-in (onboard) or aftermarket. Built-in or OEM telematics are commonly subscription based such as OnStar by GM. Companies are beginning to use aftermarket plug-in telematics to track their vehicles and how or where they are driven. The devices are plugged into and powered by the diagnostic port usually located in the driver’s footwell area. Insurance companies offer similar devices to track driver behavior to possibly yield a discount on premiums.

Regardless of the type of system, infotainment or telematic, accessible data is potentially stored in the vehicle or in a cloud. The data is not only obtained for insurance discounts or safety related purposes, but also for incident related situations being investigated at a forensic capacity.

For additional information on Infotainment & Telematics, or to arrange a presentation, contact Robert S. Kinder, Jr., BSME, Automotive / Mechanical Engineer with DJS Associates, at or via phone at 215-659-2010.

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construction code expert witness

Construction Disputes-Providing Proper Construction Cost Analysis

David A. Doddridge, Building Code and Construction Consultant ::::

Construction projects can offer many opportunities to unscrupulous contractors. Often, a contractor will “front load” the payment schedule within the contract to ensure that he stays financially ahead of their client. Known as “change order artists”, some contractors will also capitalize on change orders by overinflating the costs associated with each change. This, among other things, can cause the relationship between the contractor and the homeowner to deteriorate.

When a contractor is taking too long, making promises he cannot keep, charging excessive amounts for simple changes to the contract, or demanding payment in exchange for “showing up”, the relationship between the contractor and the homeowner often deteriorates to the point where the contractor will simply abandon the project. At this point, if the contractor front-loaded the payment schedule, the contractor will walk away with an amount that far exceeds the value of the work-in-place provided, and the homeowner is faced with the task of either finishing the project themselves or hiring another contractor to take over. Either of these scenarios can present unique challenges, both from a cost standpoint and a time standpoint.

If the dispute ends up in litigation, even more time and expenses will be incurred, not only by the homeowner but by the contractor as well. The attorney hired by the homeowner will typically engage an expert witness to evaluate the case. An expert witnesses’ job would then be to document the condition of the project before any additional work is performed to preserve and document the scene. The expert will then perform a forensic construction cost analysis to determine the value of the work performed by the contractor. In doing so, it is important that the expert utilize published, recognized and reliable construction cost resources so as not to jeopardize the expert’s impartiality. By using such construction cost resources, such as the R.S. Means Construction Cost Guides, the expert cannot be accused of skewing their opinion of costs in favor of their client and can avoid a potential Daubert Motion filing by the opposing counsel.

Further, the engaged expert may often determine the cost-to-cure any defective workmanship performed by the original contractor. These costs are then used by counsel to help determine the amount of the claim.

David A. Doddridge is a Building Code and Construction Consultant with DJS Associates and can be reached via email at or via phone at 215-659-2010.

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