Expertly Speaking

“Fore! A Non-vehicular Drive Tracking Example”

Laurence R. Penn, Senior Forensic Animation / Video Specialist

Never one to turn down a challenge, when asked if I could track a ball just over 1.5 inches in diameter traveling at an average of 90 miles per hour in footage shot from a drone, I was more than happy to oblige. The footage I was working with was filmed from a DJS drone at the 2019 Legal Aid Golfing Outing in Plymouth Meeting, PA. Tracking rigid and organic objects in video footage can have varying degrees of difficulty. One of the first obstacles is the resolution and clarity of the video. Motion blur artifacts introduced by extremely high speeds, low lighting conditions or slow camera shutter speed can add an additional layer of complexity to the analysis. The distance of the subject from the camera also becomes an issue. Tracking a rigid body, such as a vehicle, with fixed features that stay at a relative distance from each other will also be a lot less intensive to track than an organic object such as a pedestrian, where posture and reference points are constantly changing.

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The health and safety of our employees, partners, and clients are of utmost importance to DJS Associates, Inc. Amidst the COVID-19 pandemic, we have encouraged all employees to work remotely in order to prevent and limit the spread of illness. DJS administrative staff, engineers and 24/7 rapid response field crew will continue to work remotely until further direction from the state.

As we continue to provide our clients with the efficient, dedicated service they have always been accustom to, we provide you with the following links:

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“Speed (and more) From Video”

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

Surveillance cameras are becoming increasingly more prevalent in today’s world, and videos from these surveillance cameras are oftentimes invaluable to an accident reconstruction analysis.

In this example, the movement of a municipal trash truck is captured by a residential video doorbell. This is just an example, as the trash truck was simply making its routine weekly pickup and was not involved in a collision. We sharpen our skills by evaluating such videos for practice.

Surveillance Trash Truck

As you’ve likely seen in our other examples, we can evaluate the speed of a vehicle from video, even if the video shows only a fraction of a second of the vehicle’s movement. In this example, we’ve evaluated average speed of the trash truck as it moves from one stop to the next. Inherently included in this evaluation is the distance the truck traveled over this same time period, being that speed is calculated from distance divided by time. Truck acceleration from a stop and deceleration back to a stop could also be calculated, if necessary. You can see the acceleration in the increasing speed at the beginning of the plot, then the speed tops out at about 8 mph, after which the speed decreases, which is the deceleration heading toward the next stop.

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Storm Damage Claim Requires Structural Engineering Analysis

Ken Basden, P.E., S.E., Structural Engineer

Case Description: A structural engineering opinion was requested on a residential storm damage claim referencing “damage sustained to the rear porch of the property causing separation at the rear door, wall and rear window.”

Upon arrival to the site, a wide crack in the masonry veneer at the rear porch was observed. The crack was in a horizontal mortar joint about half-way up the wall and extended from the door frame to a nearby window.

The general structural condition in the vicinity of the rear porch was then documented. During documentation, it was observed that the brick veneer had also separated from the bottom of the porch door and the bottom of the porch window. Furthermore, there was a gap at the bottom of the wall between the brick veneer and the porch slab. Out away from the wall, a crack in the porch slab was also noted. The crack ran full length across the porch.

Expert Analysis: Based on observations, it is opined that the damage to the brick veneer and porch slab is due to downward movement of the porch slab relative to the main structure. When the brick veneer was constructed, it was built on top of the porch slab and tied to the stud walls. As the porch slab moved down relative to the main structure, it pulled away from the bottom of the brick veneer. The weight of the unsupported brick imposed vertical tension stresses in the veneer, and the stresses were relieved at the mortar joints. The horizontal mortar joint crack between the porch door and window, the separation of the brick from the bottom of the porch door, and the separation of the brick from the bottom of the porch window were all caused by downward movement of the porch slab relative to the main structure. The downward movement also caused the crack in the slab out away from the wall.

Confirmation of a storm in the area on the reported date of loss was noted; however, the maximum recorded sustained wind speed and gust speed of 18 mph and 35 mph respectively are well within building code requirements. It would require significantly higher wind speeds to exceed the presumed allowable masonry stresses. The damage to the brick veneer was unrelated to the storm.

Ken Basden, P.E., S.E., Structural Engineer with DJS Associates, Inc., can be reached via email at or via phone at 215-659-2010.

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Clean and Repair It and They Will Come…Maybe

Jeffrey T. Willoughby, CPA, CFF, CFE, Forensic Accounting Expert
James A. Stavros, CPA, MBA, Forensic Accounting Expert

Case Synopsis: A commercial painting and cleaning contractor was hired as the general contractor to clean, repair and paint several bridges along a section of interstate highway lasting several months. The contractor hired another company to be the primary subcontractor performing painting and cleaning work. Part of the compensation for the primary subcontractor was to include a portion of the profit earned on the contract based upon the work completed. The agreement between the primary contractor and the primary subcontractor was oral.

The cleaning and painting work slowed during the winter months due to the cold weather. The subcontractor left the job site and did not return. The general contractor completed the remaining portion of the contract, working through the winter months and hiring additional workers to replace the labor expected to be performed by the primary subcontractor. The general contractor completed the work outlined in the contract at a profit, and, because of provisions in the contract, earned performance bonuses for early completion of certain portions of the contract.

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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 or via phone at 215-659-2010.

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