Hydroplane Speed on Flooded Highway

General Crash Reconstruction Tecnhiques
Crash tests, Pole Impacts
brian
Posts: 499
Joined: Tue Jul 14, 2009 10:52 am

Hydroplane Speed on Flooded Highway

Post by brian »

Q: I'm looking for any literature or other references that address hydroplaning. I'd like to know how to do a hydroplane speed analysis.
A: The following is from our book McHenry Accident Reconstruction in the section Vehicle Control Factors: (a list of references is also below)
Hydroplaning OR Hydrodynamic Drag?
Dynamic hydroplaning occurs when the amount of water encountered on the roadway by a rotating tire exceeds the combined drainage capacity of the tread pattern of the tire and the texture of the pavement. The mass and viscosity of the water cause it to resist being displaced from between the tire and the pavement, thus generating lift forces on the tire which reduce tire contact with the pavement. When the lift forces are sufficient to completely support the load on the tire, contact with the road is no longer made and full dynamic hydroplaning is said to occur.
Prior to the onset of full tire hydroplaning, a transitional condition occurs in which the surface contact area of the tire footprint is decreased as the vehicle speed is increased. This condition is sometimes referred to as “partial hydroplaning” and it is associated with a reduction in the effective friction coefficient. The capacity of the tire tread grooves for water flow is an important factor in limiting the development of partial hydroplaning. Thus, at a given operating condition on wet pavement, the effective friction coefficient is reduced by worn tires.
The following physical factors are involved in the occurrence of hydroplaning of automobile tires:
  • Tire construction type, size and aspect ratio
  • Tire loading
  • Tread depth
  • Tread pattern
  • Inflation pressure
  • Pavement surface texture
  • Water depth
  • Length of path in standing water
  • Vehicle speed
Dynamic hydroplaning of automobile tires occurs on relatively thick water films, generally greater than 0.080 INCHES deep, and at speeds greater than 40 MPH (e.g., Ref. [1], [2], [3], [4] e.g., see Figure 1 from Ref. [1] and Figure 2 from Ref. [2]). A path length of at least 30 feet is generally required to have a significant effect on vehicle control (e.g., Ref. [3]. [4, [5]). The decrement of effective friction with vehicle velocity is depicted in Figure 3 from Ref. [2], and the decrement with tire wear is depicted in Figure 4, also from Ref. [2]. The analytical/simulation task is complicated by the fact that at speeds above approximately 30 MPH, the front tires will generally have cleared the track of water for the rear tires (e.g., Ref. [3],[4]).
Figure 1 Hydroplaning Speeds vs. Small Water Film Thickness, from ref [1]
hydro1.jpg
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Figure 2 Susceptibility of some ground vehicle to hydroplaning (From Ref. [2])
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Figure 3 Curves of the coefficient of friction for different velocities and water depths, Tire 5.60-15, Load 551 Lbs, Tread 100%, P=22 PSIG (Note: 0.5 mm=0.02 in, 1.0 mm=0.038 in) (Ref. [2])
hydro3.jpg
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Figure 4 Effect of tread pattern groove depth on braking grip, “flooded” road conditions (Ref. [2)
hydro4.jpg
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REFERENCES:
  1. Huebner, R.S., Reed, J.R., Henry, J.J., “Criteria for Predicting Hydroplaning Potential”, Journal of Transportation Engineering, Volume 112, No. 5, Sept. 1986.
  2. Clark, S. K., editor, Mechanics of Pneumatic Tires, U.S. Dept. of Transportation, NHTSA, 1981
  3. Ivey, D.L., Mounce, J.M., “Water Accumulations”, Chapter 6 of The Influence of Roadway Surface Discontinuities on Safety, Transportation Research Board, National Research Council, Washington, D.C., 1984.
  4. Navin, F., “Hydroplaning and Accident Reconstruction”, SAE Paper No. 950138.
  5. Hight, P.V., Wheeler, J.B., Reust, T.J., “The Effects of Right Side Water Drag on Vehicle Dynamics and Accident Causation”, SAE Paper No. 900105
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