Fuel Tanker Truck maximum slopes

[Michael Frankowiak]

I am a civil engineer designing a tanker truck delivery driveway in Maryland, USA. The connecting road is about 10% slope and the entrance connects perpendicular to the connecting road.
Without re-grading the connecting road the entrance ramp will need to match grade at 10%. My question is, is there a recommended maximum slope and cross slope for the entrance road that the design needs to adhere to so condition do not result in a roll over situation? Auto-turn at 5mph has been performed for turning radii design.

Thanks
Michael

 

[dik]

The API may have some standards... 10% is about as great a slope you would want... Although they have ample clearance, for other vehicles you might consider vertical transition curves to 'round' out any abrupt changes in grade.

Dik

 

[chicopee]

One thought about a 10% grade for the driveway, would you be able to empty out any of the compartments of the tanker?

 

[racookpe1978]

Coming "off" the road going uphill will likely not cause an interference: The road grade creates extra clearance between the truck wheels and the trailer wheels. (As I read the problem, the exit is going uphill, right?)

1. At the top of the 10% slope, how will you ease the truck's transition back to flat? Around here, we've had many trucks get stuck crossing railroad grade crossings that are too "high" across the tracks for the trailer auxiliaries to clear.
2. How will you ensure the trucks don't try to make the 90 degree turn at 10 or 15 mph?

 

[dik]

I usually use a transition zone for anything more than 8%, but, a truck has sufficient clearance that 10% shouldn't be too difficult.

Dik

 

[Michael Frankowiak]

Currently the only slope that is 10% is the first 10' around the 40' radius of the turn. We were able to use a couple short retaining walls on the upper side of the slope to extend the 1% 50' unloading zone that we are transitioning to. The entrance is on a campus and the adjacent road is a dead end and has to stop at an intersection right before turning on to this road so we are fairly certain a truck will be at 5mph or slower. I found NTSB incident reports that sited cross slope was the biggest concern. Maryland state highway stated cross-slopes of 4% or higher should be avoided.

Thanks for all the input
Michael