Recently, NAPARS has been hosting some great presentations from the likes of Jeff Muttart, Wade Bartlett, James Loftis, Kent Boots, and the inspiration for this week’s post, Alan Moore. If you’re not a member, you can sign up here…it’s a good use of $65, IMHO.

Speed determination method I’m starting to explore

Last month, in true form, Alan offered an excellent presentation on determining vehicle speed via audio using two methods: doppler shift and engine speed [RPM], and therefore ground speed. Alan found that doppler effect evaluation can result in larger errors (15%+ at times), whereas speed from RPM was usually within 2%. He plans to publish the results in SAE shortly.

Similar work was performed by Cevher, et al., in a 2009 paper titled, Vehicle Speed Estimation Using Acoustic Wave Patterns, where the authors detailed fairly impressive results. Granted, I have much more reading of that paper to do. Additionally, in a 2017 paper titled, Video Analysis of Motorcycle and Rider Dynamics During High-Side Falls, Nathan Rose, et al., performed the speed from RPM analysis on a motorcycle case, calculating a speed of 37.9 mph, which agreed with the 37.0 mph calculated via traditional video methods.

Most recently, Henry Vega et al. published a paper titled, Speed Determination Using Audio Analysis of Dash Camera Video for Vehicle Accident Reconstruction. In that paper, the authors investigated the feasibility of using dash cam audio to determine speed as a vehicle traverses bridge expansion joints and a rumble strip, finding good alignment with VBOX data.

Most often, we’ll be able to rely on video imagery for speed determination. However, there are situations where audio might provide additional information, or if the crash is off camera, the best information. If you’re interested in adding this tool to your kit, I recommend reading the papers above and heading to the members section of NAPARS to watch the recording of Alan’s show!

I hope you have a great weekend!

Lou Peck
​Lightpoint | Axiom

P.S. If you want Moore Alan, here's a podcast where he and I discuss the state and future of autonomous vehicles.