I have 33 years of experience, and specialize in the field of traffic crash reconstruction with specific knowledge in the areas of collision analysis, vehicle dynamics and commercial vehicles. I have published on such topics as various traffic crash reconstruction topics, sound emissions from oversnow vehicles. I have testified 40 times on topics such as traffic crash reconstruction. I have written and had published three textbooks in the field of traffic crash reconstruction. My son was a co-author on the last text, published in 2006.