Semi-Truck Maximum Vertical Slope

[EJSweeney]

Wondering if anyone has ever come across design standards RE Maximum Vertical Slope for semi-trucks as related to parking lot movements. Reviewing a design plan for a proposed shopping center that includes onsite access roads as steep as 18%. Seems like this would pose potential problems for larger delivery vehicles, but not much success finding documentation on the subject.

 

[IRstuff]

Problems in what sense? Cars and trucks routinely handle the hills in San Francisco, which are generally way worse than 18°

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[EJSweeney]

Concerned RE potential truck-trailer conflicts traversing a grade break as significant as 18% within a limited area such as a parking structure. I spoke briefly with an industry Design Engineer who said they typically consider over-the-road design grades only, which may differ from onsite access design grade issues. Wondering if anyone has personal experience with a design issue of this nature.

 

[CarlB]

18 percent is awfully steep. Many fire department jurisdictions have 10% as the maximum allowed slope for a fire access road.

From the International Fire Code;
"D103.2 Grade. Fire apparatus access roads shall not exceed 10
percent in grade.
Exception: Grades steeper than 10 percent as approved by
the fire chief."

If the 18% is short (say less than 100%) with gradual transitions at top & bottom it may manageable. There was a recent post with reference to the Green Book, a section on allowable slopes vs. length for trucks.

 

[EJSweeney]

Thanks for the input Carl. That confirms some of the verbal feedback I have received from a few others I have spoken with.

 

[IRstuff]

My bad, NOT worse than 18°, but close:

http://en.wikipedia.org/wiki/Filbert_Street_(San_Francisco)

Makes you wonder how the SFFD handles fires on those streets...

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize