Ball-banking in an SUV?

[ACtrafficengr]

I've always understood that, as the former version of he NYS manual used to say, ball-banking should be done in a standard passenger car, not a truck or sports car. This is because a stiff suspension or a high C_g will skew the results.

I can't find any reference to this in the National MUTCD or the current Green Book. Am I missing something?

I once heard of a paper showing that vehicle type doesn't have much impact on the ball bank indication. Can anyone tell me where to find information confirming or refuting this assertion?

I'm asking because Management wants to replace our lone passenger car with an SUV. It makes sense, because it has to double as a construction inspector's vehicle.

"...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

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[francesca]

This paper may help you:

http://pubsindex.trb.org/document/view/default.asp?lbid=506960

 

[ACtrafficengr]

Thanks, Francesca! I found that abstract about the same time you posted it.

The abstract ends with the statement "The influence of body-roll on ball bank indicator readings appears to be negligible when using typical passenger cars to determine safe speed on horizontal curves."

That doesn't answer my question about light trucks, and TRB wants $25 for the paper. I'll see if I can borrow a copy from somewhere.

"...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

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[francesca]

Yes, I saw that, but I thought that maybe the sentence

Additionally, the influence of vehicular body-roll on ball bank indicator readings was investigated.

pointed to them having tried various vehicles. Unfortunately I can't get an online version through my college's library.

 

[ACtrafficengr]

NYSDOT came through for me. The paper discusses the effect of body roll rate on the ball bank indicator. The authors state that a sports car will roll 3 degrees per 1 g of lateral acceleration, and a passenger car is around 7 deg/g. This, they calculate, results in a .48 degree difference in ball bank indication at 100 km/h.

"...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

"I'm searching for the questions, so my answers will make sense." - Stephen Brust