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Right lane higher then Left Lane impact

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Right lane higher then Left Lane impact

Post by Gazman36 » Mon Sep 11, 2017 6:00 pm

Question....I was sideswiped by a vehicle when I was in the right lane , (which is higher in grade then left lane ) by a vehicle from the Left lane , ( which is lower in grade )...The damage on my vehicle was at 36" and bottom of her mirror is at about 38"... I was told that she could not have impacted me because of this 2" differential. Can anyone confirm that the grade difference can in fact be the cause of the difference in height....Any feedback would be appreciated..

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Re: Right lane higher then Left Lane impact

Post by actar670 » Sun Sep 17, 2017 6:19 pm

When you talk about "grade," I am assuming you are talking about the superelevation of the roadway, which is the lateral grade of the roadway. I wouldn't expect the "grade" to make a difference in contact height if the "grade" is constant across the travel lanes, as the contact points on the two vehicles would be essentially occupying the same lateral position on the roadway at the moment of contact.

You might, however, consider the lateral acceleration being experienced by the vehicles at the moment of impact. If both vehicles are traveling around a left-hand curve, then both would be experiencing a weight shift onto their right-side tires/suspension. If both vehicles experience about 1" of lateral weight shift as they travel around the curve, the contact points would be about 2" higher on the vehicle in the left lane and about 2" lower on the vehicle in the right lane.
Bruce McNally
McNally & Associates ARS, LLC
41 Champlin Ridge Road
Rochester, NH 03867
Office (603) 516-4560
Web http://mcnallyassociates.com

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Re: Right lane higher then Left Lane impact

Post by Gazman36 » Sun Sep 17, 2017 8:40 pm

Thanks Bruce..At What speed would you estimate would generate a 1" Lateral shift ? I tried uploading a photo of the surface , but the file size is to large. Let me know if you would like me to email you the photo of the road surface to confirm that the difference in right lane height( Higher surface ) vs left lane height ( lower surface ) can or can not potentially explain the 2" difference further...Sorry, I'm an electrical engineer , not a Highway engineer!

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Re: Right lane higher then Left Lane impact

Post by actar670 » Fri Sep 22, 2017 7:35 am

The amount of weight shift and change in ride height depends upon several variables, including the characteristics of the suspension systems of both vehicles, the loading of the vehicles, the geometry of the roadway and the speed at which the vehicles were traveling.
Bruce McNally
McNally & Associates ARS, LLC
41 Champlin Ridge Road
Rochester, NH 03867
Office (603) 516-4560
Web http://mcnallyassociates.com


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