Are there any forensic civil engineers in the house?

[ACtrafficengr]

I'm a county engineer. One of our town highway superintendents asked us for technical assistance at a site of several fatal crashes. I have a hypothesis about what may have contributed to the latest crash, but I'd like to run it past a crash reconstruction or forensic specialist before making my recommendation. Would anyone be willing to lend an ear?

Thanks.

 

[ACtrafficengr]

I had forgotten about this picture. Maybe it will set the scene better. The crest is just in front of the grey pickup.

It's an old country road that may have never been properly engineered, and is now low-density suburban. The roadway is 1.3 miles long and 20 feet wide with narrow grass shoulders. If it were a subdivision road, the cross slope probably wouldn't be so badly out of shape.

Between the snowplow operators, the rich guy with the horse trailers, and the Porsche-driving dentists at the country club, any vertical calming features are likely to be highly unwelcome.

TerryScan, even if the vertical curve is lengthened so they don't get the hang time to begin with?

 

[TerryScan]

Thanks AC,

"A picture is worth..." The photo helps a good bit picturing the scenario...but it's still a bit hard to tell - is it it's own little "hump" in the road?

I do agree that a longer vertical curve may help. If one is to bother with it, I would make it A LOT longer.

*Can one cut most of that crest out?
*Otherwise, I would be trying to lengthen it by starting a fill transition at that drive to achieve length.

 

[zelgar]

Sounds like a case of "Damned if you, and damned if you don't"

If anything, either eliminating the bump or adding additional material to the roadway to make the slope more gradual to,from and at the bump are the only things that would work to make everyone except for the thrill seekers happy.