Rolling Resistance for Earthmoving Vehicles

[mabn]

Hello all,

I was wondering if anyone has had any experience relating rolling resistance (or friction) factors to certain material types and characteristics, when examining an earthmoving situation involving tyred vehicles.

I have seen guidelines that correlate tyre penetration to rolling resistance; but tyre penetration is difficult to predict before a job is started. There are various other factors that come into play when examining the interaction between the tyres and the material.... moisture, underlying base of the haul road, frequency of maintenance, etc.

Has any work been done, or does anyone know of any guidelines, correlating the factors that influence rolling resistance to the actual measured rolling resistance in the field? Rolling resistance (or a friction factor) seems like an important factor when analyzing the productivity and cost of an earthmoving job, although there seems to be a lack of information readily available.

Any input or comments would be greatly appreciated

Mabn

 

[Laser28]

I don't know of a specific study involving rolling resistance vs soil types, but there was a World Bank study that examined rolling res. for trucks on asphalt, concrete and gravel surfaces. It showed that there was adistinct savings in energy consumption as the surface became more rigid. The savings were up to 10% for concrete over asphalt for heavy rigs, if I recall correctly.

The Tar Sands project in Northern Alberta used roller compacted concrete to reduce rolling res. for very large off-road vehicles, and the savings in energy consumption and repairs more than covered the cost of the 18" pavements.

 

[jheidt2543]

I wouldn't think the asphalt industry would like to hear this! A 10% fuel savings for using concrete pavement instead of asphalt, that is pretty significant at $1.75/gal. Do you have a citation for that study by the World Bank?

 

[Laser28]

UPDATE:
Thanks for asking about the study. The original study was conducted (I believe) for the World Bank) about 25 years ago, and one of the researchers (Zaniewski) repeated the work for FHWA. That was published as well by PCA. A more recent study was completed by the National Research Coun cil in Canada. The references:

Taylor, Gordon, Marsh, Philip, and Oxelgren, Eric, 'Effect of Pavement Surface Type On Fuel Consumption', National Research Council of Canada, Centre for Surface Transportation Technology, Report No. CSTT-HWV-CTR-041, Ottawa, Ontario, August 2000.

Zaniewski, J.P., 'Effect of Pavement Surface Type on Fuel Consumption', SR289.01P, Portland Cement Association, Skokie, Illinois, 1989.

 

[tarsandman]

Hey mabn

You have to be careful when considering rolling resistance and trying to tie it to certain material types. Take gravel for instance, the rolling resistance we encounter can range from 3% to 5% on the same road but with different weather conditions (dry summer conditions to wet spring thaw). We have some temporary clay and sand roads that if placed and maintained in dry conditions will have pretty low rolling resistances but if they get wet and are subject to prolonged, un-maintained haulage…you are looking at 15% resistance or more prior to a dozer being dispatched to level the ruts!

We allow a maximum 2-inch surface deflection for our permanent gravel haul roads, which, under ideal conditions, have a rolling resistance of approx. 3% - 5%, as per my comment above. We’re running Cat 797, 400-ton haulers on these roads and they (roads and trucks) are performing quite well.

tarsandman

PS: Laser28, I’d be interested in knowing at what tar sand mine the roller compacted concrete worked such that a cost savings in trucking could be realized. Syncrude tested a section of roller compacted concrete back in the late 80’s and given the high cost of construction and poor performance it was considered un-economical. I don’t think it lasted long enough to evaluate if a haulage cost saving could be realized.

 

[mabn]

Thank you for the input. The conditions tarsandman describes are the same pitfalls I'm running into. Rolling resistance can be so variable.... because there are so many variables that influence it, go figure. When production hasn't started and you are trying to predict what the rolling resistance might be (another one of those variables of production that can make a difference, especially when you're dealing with a range of 3% to 20%, depending on the circumsatances) it's very hard to peg something down.

In the past I've assumed about 3% along permanent roads and 5% in digging areas, dumping area, areas not maintained.... but how accurate can this be when you describe the types of ranges out there? That's why I brought up the material type question, there's probably some other better variable to use to predict rolling resistance? I'm not sure.