Roadway Ruts Cause Hydroplaning

Ruts cause hydroplaning and before you can slow down, you feel your car move like it is on ice and you no longer have control of your car. You cannot steer or brake to slow down. Result...another traffic accident. 

Ruts cause hydroplaning. Ruts are depressions or grooves worn into the road or path by the travel of wheels of vehicular traffic on the highway. 

Heavy traffic on roadways creates ruts in asphalt pavement surfaces. Travel lane pavement supports thousands of vehicles in the same path every day, including heavy trucks. This repetitive loading of the pavement causes stress in asphalt and subgrade and in certain situations will cause the pavement to move and depress. 

Ruts prevent water from flowing off the roadway. Ruts redirect storm water along the longitudinal path of travel. The water will stay in the rut until it overflows it. In the situation of a vertical grade, the water flows down the roadway increasing in depth as it flow downhill. 

An example of pavement failure which can lead to a traffic accident.

Water in Ruts can cause wheel drag or vehicle hydroplaning

Another danger with ruts filled with water is tire drag. This is particularly dangerous when one tire path has not water and the other tire path is filled with water. The deeper the water, the greater the wheel drag. The vehicle will pull to the side which has the greater depth of water. The vehicle will either be pulled toward oncoming traffic or to the ditch. Both can be a hazard. 

What causes ruts in pavement? Highway pavement ruts are usually grouped into two basic types: asphalt mix rutting and subgrade rutting. 

Asphalt mix rutting occurs when the design of the asphalt mix is such that the structural strength of the mix is unable to support the volume of traffic and the weight of the vehicular traffic. This is a result of a design problem or a construction compaction problem. In this case, the subgrade does not rut but the wheel path of the pavement surface depresses under the weight of the vehicles. 

Subgrade rutting is created when the subgrade depresses under the weight of the traffic and creates ruts in the wheel path of vehicular traffic. In this case, the pavement settles into the subgrade causing surface depressions. Both types create depressions and the ruts cause hydroplaning. 

Insufficient compaction of the asphalt layers during construction. If it is not compacted enough initially, asphalt pavement could continue to compact under traffic loads. 

Subgrade rutting is often the result of inadequate pavement structure. Improper mix design could be from excessively high asphalt content, excessive mineral filler or insufficient amount of angular aggregate particles. 

Measuring the Depth of Ruts 

Measuring the depth of ruts is very simple. It is as simple as have a straight edge and a steel measuring tape. Lay the straight edge across the roadway perpendicular to the direction of travel and measure from the bottom of the straight edge to the asphalt pavement. 

Four commonly used methods 

  1. Using a 10-foot straight edge. 
  2. Survey of cross sections of the highway 
  3. A Face Dipstick and 
  4. Vehicle mounted laser equipment 

Maintenance of Highways with Ruts 

Ruts prevent storm water from flowing to the side of the road into ditches or gutters. Since storm water trapped in ruts is a common contributing factor to hydroplaning crashes, it is important to regularly inspect roadways prone to rutting and to repair roadways when ruts develop. 

Several methods can be used to repair roadways with ruts. Ruts in asphalt pavement can be filled with asphalt. The pavement can then be over-laid with another layer of asphalt. Better results have been achieved by grinding off the pavement surface. The crown and proper cross slope should be reestablished. Then pavement can be resurfaced. 

If the ruts are formed due to deformation of the sub grade below the pavement, the only long-term repair is usually full-depth reconstruction of the road. The subgrade must be stabilized with engineered material before resurfacing. 

Investigation to determine why the roadway pavement is Rutting 

A heavily rutted pavement should be investigated to determine the cause of the pavement failure. Was the sub-grade and asphalt insufficiently compaction? Or is the rutting a result of low structural strength sub-grade or a poorly designed mix. 

When a pavement begins to show ruts, highway maintenance personnel should monitor the rutting regularly. Should the rutting continue and the pavement ruts sufficient to redirect water, the pavement should be leveled and over laid. 

Ruts cause hydroplaning and hydroplaning is dangerous to all persons on the highway. 

Need a Hydroplaning Expert?

Call Elvin Aycock, PE, PH, PLS, ACTAR. I am a licensed professional engineer, licensed professional surveyor, a professional hydrologist and certified as a traffic accident reconstruction engineer. I have been a professional engineer for forty years and traffic accident certified for more than 14 years. 

I know that ruts cause hydroplaning because I have analyzed roadways and found that pavement failure was the cause of the roadway depression in travel lanes of vehicles.

Have a question? Here's How To Contact Atlanta Engineering Services

Related Information about Traffic Accident Reconstruction

Types of traffic accidents

Collision analysis in 10 steps

The accident scene investigation 



View a sample engineering report here

Why you need an expert witness

Calculating the stopping distance


Vehicle speed calculator

Accidents involving motorcycles

How a vehicle inspection analysis can help you after an accident

Reconstructing accidents involving Non-Commercial trucks



Was it poor design or layout that caused the accident?

See real 3D accident simulations with this link

More 3D accident reconstruction videos can be found here

See actual photos of traffic accidents here