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NEWSLETTER
Second Anniversary Edition	November 10, 1997

Celebrating Our 2^nd Anniversary

GILLENgineering now embarks on its third year of service. On November 10, 1995, a new engineering company was formed. With much thanks to the confidence and support of you, our customers and colleagues, and much hard work on our part, we look forward to a continuing future of engineering excellence.

This newsletter will be published on a recurring basis. Its purpose is to bring you information about engineering technology you can use and to inform you about our activities and capabilities. If you have any questions or comments, please direct them to:

GILLENgineering , P.O. Box 122 , Marengo, IN 47140

Phone/FAX (812) 723-4290 ....plus.... e-mail: lggillen@gillengineering.com

Or: Visit Us On The Web

To find out more about our company, visit its Web Site at http://gillengineering.com. There is a FEEDBACK section there that you can use to send an e-mail message. Your thoughts and comments mean a lot to us and we would like hearing from you.

Photogrammetry

There is probably no question I have been asked more often during my career than, "What is photogrammetry?" The lay answer is: it is the science of making measurements from photographs. The Manual of Photogrammetry indicates the origin of the word: "It is derived from three Greek words, photos meaning "light", gramma meaning "something drawn or written," and metron meaning "to measure." Add the myriad of technological advancements during this century and photogrammetry now encompasses many types of electromagnetic sensing, intensive statistical processing of digital images and output formats applicable to simulations and animations.

Photogrammetry is used in failure analysis and accident reconstruction in several key ways, including:

.... measuring road features (i.e., skid marks , gouges and potholes) preserved only in photographs

.... using photographs to measure the crush of accident vehicles which have been recycled

.... preserving the shape of a structure or vehicle which has limited or difficult access

GILLENgineering uses a flexible, efficient and sophisticated computer program, PhotoModeler by EOS SYSTEMS. If there is a distance, a shape or a pattern you wish to know the dimensions of, think of using photogrammetry and we may be able to solve your problem.

Tools Often Used

In addition to photogrammetry, we use many other tools, and more are being added. The following list includes the most often used equipment and programs:

.... MathCAD: numerical problem solving

.... AutoCAD: scaled graphics and exhibits

.... EDCRASH: solves for Delta-V from crush

.... EDSMAC: vehicle collision simulator

.... Corel Profession Office 7: written reports

.... Total Station: 3D site surveying

.... Hitachi Hi-8 Video Camera

.... Minolta 35mm SLR Camera (calibrated for photogrammetric measurements)

.... Research via Web, Company Library and Technical Associations

Intersection Sight Distance

Should an intersection have yield signs, stop signs or is it acceptable for it to be uncontrolled? Standards for the usage of these control devices are given by the American Association of State Highway and Transportation Officials (AASHTO). These standards are detailed in the AASHTO publication A Policy On Geometric Design of Highways and Streets¹, also know as "the green book."

Intersection sight distance is the distance from a vehicle, forward to the intersection, to the path of travel of a potential crossing vehicle. With sufficient visibility across an intersection corner and for a given speed limit, there would be time for a vehicle to either slow down or speed up and thereby safely cross the intersection. Higher speeds obviously require a larger sight distance. For example, the standard since 1984 would require a minimum sight distance of 400 feet for a design speed of 50 mph and a minimum sight distance of 525 feet for a design speed of 60 mph. An intersection meeting these requirements may be operated as an uncontrolled intersection. If an intersection has less sight distance, either the speed limit should be lowered or the intersection should be controlled with either YIELD or STOP signs. In practice, uncontrolled intersections are found only on very low-volume roads.

For intersections with sight distances of less than 220 feet and 260 feet for design speeds of the same 50 mph and 60 mph, respectively, YIELD signs are no longer appropriate and the intersection should be controlled by STOP signs on the minor road.

Once an intersection is controlled by 2-way STOP signs, a different criteria is used to define the sight distance. The driver of the stopped car must now have enough time to look both directions, safely accelerate into and then either cross or turn onto the major road. For example, in the case of a passenger car crossing a 2-lane major road where that through road had a design speed of 50 mph, the sight distance down the through road would be 500 feet. If the site distance is less than 500 feet, remedial measures include, among others, reducing the speed on the through road or installing 4-way STOP signs.

¹ ISBN 1-56051-001-3, available from AASHTO Publications at 1-888-227-4860. Cost $27US.

ACTAR

In late 1990, twelve professional accident reconstruction associations and societies with international representation met to explore the possibility of forming an internationally recognized accreditation program open to both police and civilian accident reconstructionists alike. The Accreditation Commission for Traffic Accident Reconstruction (ACTAR) is the result of that coalition of professional associations and societies.

Participation in ACTAR is totally voluntary. Accreditation is provided to an individual following submission and acceptance of application and satisfactory completion of an eight hour examination. Eligible individuals are those involved in preparing or offering expert opinion testimony with respect to the analysis of an automobile traffic collision. As of September 1997, a total of 536 individuals have attained accreditation and 85 are awaiting testing.

ACTAR has adopted the following definition of "Accident Reconstruction:" "...a systematic process of evaluating the evidence associated with a particular collision sequence and applying accepted physical principles in order to ascertain how the collision occurred..."

Individual accreditation is valid for five years and may be renewed for an additional five year period at any time upon completion of 80 CEUs from acceptable training programs.

ACTAR may be contacted in the following ways:

ACTAR

PO Box 5436 , Hudson, FL 34674-5436 Ph. 1-800-809-3818

http://www.safetycenter.cmsu.edu/ACTAR/actar.htm

or through GILLENgineering (Larry Gillen was awarded ACTAR registration #223 on October 13, 1993)

Regardless of your views on the need for licensing and accreditation programs (and there is much room for opinion on this subject) , it has been my experience ACTAR is a well-conceived, well-organized, active and future-oriented commission with broad and increasing support. When you need the services of an accident reconstructionist, one with ACTAR accreditation may prove advantageous.

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