Switchback Design

[ataman]

Hi

Are there any rules of thumb for the design of switchbacks (some may know it as hairpin bends) up steep slopes.

I have a road which has a gradient of 17% and need to design a switchback. What would be the recommended minimum for the following

1. Radius
2. Road cross section gradient going around the corner
3. Road longitudinal gradient going around the corner.

The road is located in a residential subdivision so it is likely to be used mostly by cars and pickups. It should be reasonably motorable though for the odd service and emergency vehicle.

Thanks

 

[LittleWheels]

Garbage trucks and removalists?

 

[francesca]

Can't you get a variance for 15% and do some extra earthwork?

 

[ACtrafficengr]

1. Design it for the largest vehicle you expect to use it. If it's residential, don't forget the occasional moving vans.
2. Even at a low design speed, you'll probably be at e_max.


"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

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