NIGHTENHELSER, STUART B.

Wolf Technical Services, Inc.

6828 Hawthorn Park Drive

Indianapolis, Indiana 46220

(317) 842-6075

(800) 783-9653

Fax: (317) 842-6974

E-Mail: stuartb@wolftechnical.com

Consultant. Expertise includes investigation of railroad accidents as well as visibility and lighting issues. Experience in accident investigation encompasses grade crossing accidents, railroad yard accidents, train braking and stopping distance issues. Strong physics and optics background encompasses night-time visibility, lighting evaluation and measurement, human vision, glare and visual obstruction of sight triangles at crossings. Advisory Board Member and Executive Vice President - NARSCI.

PRUITT, P. ANDREW, Accident Analyst

Wolf Technical Services

6836 Hawthorn Park Drive

Indianapolis, IN  46005

Phone:  (317) 966-0548  Fax:  (937) 294-3071

Website:  www.wolftechnical.com  E-Mail:  apruitt@wolftechnical.com

Accident investigator/consultant with emphasis in the areas of lighting, visibility, and human perception.  Expertise includes the evaluation of ambient/headlamp lighting, scene contrast, visual acuity, and contextual issues.  Mr. Pruitt has a broad background in the optical science field.  As a physicist with Naval Avionics Center he participated in the development of the Digital Scene Matching Area Correlator (DSMAC), the highly successful optical guidance system for the Navy's TOMAHAWK cruise missile.  As an Engineering Specialist with General Dynamics he was a major contributor in the development of the next-generation, laser-based guidance systems.  He has written numerous research papers published in such journals as Applied Optics and has filed tow patents in the U.S. Patent Office.




SOBEK, JAMES S., P.E.

Wolf Technical Services, Inc.

6836 Hawthorn Park Drive

Indianapolis, Indiana 46220

(317) 842-6075

(800) 783-9653

Fax: (317) 842-6974

E-Mail:  jsobek@wolftechnical.com

Website:  www.wolftechnical.com

LIGHTING/VISIBILITY/ACCIDENT RECONSTRUCTION.  Applying the equations of physics and mechanical engineering to perform accident reconstruction.  Specializing in lighting/visibility issues using the sciences of optics, photometry, day/night photography and videography.  Employs computer models of railroad headlamp illumination, target/background contrast, veiling glare, vehicle dynamics, time-speed-distance equations, etc. to determine object illumination levels, line-of-sight motion, target visibility and crew reaction times.  Measurement and computation of ambient and active illumination onto target bodies.  Influence of fog, rain and other factors on optical performance of train illumination systems.  His professional experience includes 20 years with the U.S. Department of the Navy, designing missile guidance systems.  He is an inventor of DSMAC (Digital Scene Matching Area Correlator), the precision electro-optical guidance system used on the Navy’s TOMAHAWK cruise missile.  Mr. Sobek holds a Degree in Physics from Thiel College and is licensed as a Professional Engineer in the State of Indiana.  In addition to NARSCI, he is a member of the Michigan Association of Traffic Accident Investigators (MATAI), the Optical Society of America (OSA), the Illumination Engineering Society of North America (IESNA), the Canadian Association of Traffic Accident Investigators and Reconstructionists (CATAIR) and two on-line discussion groups; RTA Investigators and INCR (International Network of Collision Reconstructionists).