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Dynamic Environment = Environment + Vehicle + Driver

Dynamic Environment = Environment + Vehicle + Driver

The steering wheel  is for hands-on directional control of the vehicle and directional control is fundamentally determined by what happens with the steering wheel.  How you hold and control the steering wheel has a significant affect on vehicle control and ride quality.  Low speed maneuvers require a totally different steering technique than vehicle maneuvers at extreme speed.

Roadway Environment – Where You Drive – AASHTO and MUTCD

Driving the vehicle is a complex set of ever evolving issues.  Travelling on an open freeway is very different than driving on a congested inner-city street or urban highway.  Highway Planners are concerned with the Civil Engineering associated with roadway design including traffic flow, physical environmental appearance, water drainage, sight lines, physical contour of elevation, and every other physical aspect of the roadway.  After the roadway is built then it must be maintained.  If you are interested in the foundation of roadways then research the links to the American Association of State Highway and Transportation Officials or  AASHTO and Manual on Uniform Traffic Control Devices or MUTCD.

Vehicle – What You Drive

Every vehicle has some common characteristics and some unique traits.  For new cars and trucks there is a general dynamic to how they drive.  Two similar vehicles equipped in the same manner would be expected to drive in similar ways.  Two similar vehicles equipped in a different manner would be expected to drive in different ways.

To illustrate some basic differences here is a good example with two trucks sitting side-by-side, one is a basic plain-vanilla 1/2 ton the average person might have.  The second could be a fully equipped heavy-haul 3/4 ton.  No-load operation in the 3/4 is very solid.  Load the 1/2 like the 3/4 and driving stability is compromised and the suspension could break.

Two real world examples come to mind to illustrate this difference.  One was a 1/2 ton pickup with a total of eight (8)  workers on-board pulling a trailer with their equipment.  The pickup had a loss of control and overturned in a pavement resurfacing area on the interstate after traversing a linear 1″ pavement elevation.  Simply put the truck was overloaded.

A second example is the basic 1/2 ton fitted with multiple optional load devices to permit the truck to pull a heavy travel trailer.  This truck was – suspension wise – turned into a vehicle that could deal with a very heavy load.  Inspection of the truck after the crash revealed that a rear axle had snapped at the axle flange.  Simply put, there is a difference in load capacity of the suspension systems.

Dynamic Driving = Environment + Vehicle + Driver = Where you drive, what you drive and how you drive

As the driver you have to operate the vehicle safely in the driving environment.  To say that it is imperative to keep at least one hand on the steering wheel at all times is fundamental and the Shuffle Technique can be used for general steering wheel movement.  Attention to what is going on with the vehicle ad the environment will prepare you what is coming up such as this example from the High Performance Driver Training Program:

after the classroom time, we took them on the 10 cent tour.  After taking the students through the various activities and heading back to our facility at about 60 mph the instructor would illustrate how to perform a set of controlled back-to-back 180 degree turns of the car.  After experiencing a set of driving maneuvers that they had never been through the students would conclude that the fellow behind the wheel knew something that they did not.

Attention to the vehicle and environment established a good foundation for safe driving.  Hands on the wheel and a focus on what is coming up down the road, provides a basis for you to cope with unexpected hazards.  Every roadway and every car have problems and limits.  Adding in the unexpected can bring excitement and terror such as a child running out between parked cars on a city street, or dog running out on a country road, or cresting a small incline and seeing a stopped car on the road, or seeing a steel part right in your tire travel path on the interstate.

If you have pushed the car to its limit and you have experienced a total loss of control then you have reached a terror point where you are totally along for the ride.  Outside of a proper training area, experiencing a total loss of control can be a very bad event.  In a proper training area the Skid Pad is used to gain comfort with a total loss of control and learn how to regain control after a loss of control.  Terror can be replaced with knowledge.

Maintaining optimal control is the mark of a great driver.  This is the real fun and success of successful driving.

Post Crash Analysis For Unrestrained Occupants

front-seat-deformationSeat belts are an important part of the safety systems in carsTo a trained investigator review of a Traffic Crash Report, site visit, and inspection of the vehicles can answer many questions about the technical nature of the impact.

In this analysis the objective is to provide a thorough identification of steps associated with arriving at impact speeds and assessment of seat belt usage for front and rear passengers.

approach-to-impactScale diagram Prepared

for Impact and Final Rest vehicle positions. Inspection of the crash site permitted final rest placement for the Mercury. Final rest position was not identified on the Crash Report and no specific evidence at the crash site permitted placement of the Honda at final rest. … Continue Reading

Motor Vehicle Accident Reconstruction & Biomechanical Physics – Part 3

Aerial Crush Photography 

dsc_0088-largeOn-site aerial photographs taken with the aid of a boom and perimeter grid capture collision data. This system has proven to be extremely useful in addressing collision dynamics.A brief synopsis of this method reveals its usefulness to the accident reconstructionist and biomechanical expert. 

aerial-boom-being-raised-over-carHorizontal lines for the red car illustrate 1′ of interior crush to the impact side-bar beam in the door and 1.5′ of collapse in the vehicle roof structure.  Also, shown on the opposite side of the car is a general bowing of the vehicle structure showing how impact forces are transmitted throughout the vehicle. … Continue Reading

Motor Vehicle Accident Reconstruction & Biomechanical Physics – Part 2

Vehicle Data

a004_1a011_8Making a good physical inspeciton of a collision vehicle can provide much important information about impact severity and expected injuries.  These example photographs document chest and facial impact.   It is significant to note that the steering wheel is deformed more on the left side which indicates the relationship of Principle Direction Of Force or PDOF to the vehicle and the center of mass movent of the unrestrained driver. 

a006_3a016_13Close inspection for the inside of the windshield will often show evidence of hair and blood that can be recovered for further forensic analysis.  Documentation of impact evidence is very important, especially when the investigator has to deal with the old statement “the dead person was driving“! … Continue Reading

Motor Vehicle Accident Reconstruction & Biomechanical Physics – Part 1

April 8, 2009 Forensic Engineering Comments Off on Motor Vehicle Accident Reconstruction & Biomechanical Physics – Part 1

Robert C. McElroy, Ph.D.

a008_8ABSTRACT — Accident reconstructionists rely on a wide range of methods to record and analyze motor vehicle accident information. This paper addresses contemporary methods of obtaining and analyzing collisions with emphasis on G force explanation for biomechanical analysis.

INTRODUCTION — Traffic accident reconstruction is the effort to determine, from whatever resources are available, how an accident happened. A traffic accident reconstructionist must be familiar with the application of a wide range of mathematics and specialized aspects of vehicle technology. Because of the wide range of knowledge required by the accident reconstructionist, voluntary certification is available through the Accreditation Commission for Traffic Accident Reconstruction. ACTAR certification includes education, work experience, and successful completion of a comprehensive examination.

Unrestrained driver upper torso impacts steering wheel and lower extremities impacts lower dash

Unrestrained driver upper torso impacts steering wheel and lower extremities impacts lower dash

MATHEMATICS FOUNDATION —

Mathematics are at the core of traffic accident reconstruction. Many different equations are used to determine different aspects of an accident. Sir Isaac Newton developed three mathematical laws of motion which provide the foundation for traffic accident reconstruction.

In Newton’s first law of motion an important property of matter appears. It is known as inertia, that property of matter by which an object maintains a constant velocity in the absence of an unbalanced external force. When an automobile is suddenly stopped, the passengers obey Newton’s first law and continue in their motion with constant velocity until some external force changes their state of motion. Seat belts in a automobile can provide such an external force which is much preferred to that exerted by the windshield or dashboard. Another statement is the following: A body at rest remains at rest, and a body in motion remains in motion with constant velocity along the same straight line unless acted upon by some outside force. … Continue Reading

Happy Birthday Smart Car

Smart Car

Smart Car

Smart Car has been on sale in the US for one year!  This nifty car was originally introduced at the Paris Motor Show in 1998 developing from initial sketches and design studio efforts in 1993.   Smart production began with the watch people Swatch who ultimately need the cooperation, guidance and capital of Mercedes Benz to bring the project forward to today. 

There are many great photos that show this ultimate small vehicle in all sorts of places that you would not expect.  Smart is about the size of a typical golf car but it can travel with freeway traffic and gets a lot of miles per gallon.  It is also a definite smile statement type of vehicle.  Maybe it is the size, maybe color coordination between body panels and safety frame, or maybe a statement about being concerned for environment and society. … Continue Reading