A number of years ago we paid a claim when a motorcycle was unable to stop at an intersection just past a carwash. The driver sustained serious injuries. As a result of the accident investigation, engineers were able to determine a significant amount of residue had been deposited on the lane exiting the carwash through to the intersection when compared to the opposite side of the road. This condition was a major contributing factor involving the carwash in the suit as a defendant, which subsequently resulted in a judgement.
There are a few lessons that can be learned from this particular loss as well as other hazardous conditions that can be avoided regarding slippery surfaces. One example is, many carwashers elect to use silicon based tire dressing, as opposed to water based, which without properly addressing the surface issues can increase the risk of accidents such as this.
As a car exits the tunnel, the residue is transferred not only to road surfaces beyond the carwash but all too often to public areas at the carwash. Some examples are common walkways used to vacuum the vehicles, discard garbage, offline detailing and access to vending machines. Left untreated an unsafe condition for both employees and customers is the result.
Another example of transfer would be if you have a short span from the exit of the carwash to the public roadways, investigate alternative routes to allow more time for runoff. You may also consider a downhill slope with a drain at the end of the exit ramp. Work with your local transportation department for possible assistance in this regard.
I would also suggest a routine maintenance schedule be implemented. It is often best to document each time the employee cleans/maintains the area including where, when and how. In areas of the country where freezing can be a concern a simple tool was developed to keep track each time salt was applied to control ice buildup. Download/preview 'Salt Log' this is an example that may be helpful or that you could modify to your own specifications.
Share your suggestions on how you were able to improve slippery conditions associated with carwashing.