vehicle bottoming template

ACtrafficengr · Aug 30, 2005

NYSDOT used to have a template for checking whether vehicles would bottom out at driveway or intersection entrances, but it appears to have been deleted.

A consultant designing a road reconstruction project is proposing an intersection with a 7.5% crest change of grade w/o a vertical curve (uphill approach on the outside of a superelevated curve), and another with a 13% sag change of grade (downhill approach on the inside of a superelevated curve).

I suspect vehicles will be scarring our beautiful new pavement, but need help proving it. Any suggestions?

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Maury · Aug 30, 2005

Architectural Graphic Standards has vehicle details that may be of use. I wouldn't want to see more than a 5% difference in grade without a vertical curve, and then only at a driveway or at an intersection that requires a full stop. I didn't find anything in "A Policy on Geometric Design of Highways and Streets" that addresses this situation, but I'll look further.

proletariat · Dec 13, 2005

I've had to measure vehicles before for just this purpose. Our state DOT has driveway guidelines which we stick to, but for various reasons we have had to breach those guidelines within sites. A low-boy trailer is about the most heinous thing you could ever get stuck on a driveway. I would go find me one of those and take some measurements to test the crest intersection. The worst limiting factor for the sag intersection (I would think) is the range of motion for a semi and trailer (WB-67 or similar)where they hitch together. The trailer would be prone to hitting the back of the cab unless there is some safety device on the 5th-wheel hitch to prevent it. Even then, it would be binding.

ACtrafficengr · Dec 13, 2005

I think sports cars will have ramp angle problems on sags before box trailers hit cabs. Think of a Ferrari or Corvette with a long nose and a deep front spoiler. IIRC, NYSDOT's template was a long, low passenger vehicle, like a Buick Roadmonster or Caddy DeVille.

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