Aircraft lands at speeds from 86 km / h to 250 km / hour.After landing the aircraft mustbreak quickly to reach the necessary speed for leaving the runway as soon as possible and safely. This requires at all times a good interaction and contact between the wheels of the aircraft and the pavement surface.
This is not difficult unless, the runway is wet or covered with water, in which situation may occur hydroplaning. If this happens the entire surface of the wheel is out of contact with the pavement surface. The wheel loses its ability to develop the necessary friction values for deceleration and control the aircraft.
Rubber deposits on the runway, reduce significantly when is wet, the coefficient of friction because it can not completely expelled the water located between the tire and the surface of the runway.
To obtain a high coefficient of friction in the wet runway is necessary to move or break the water film located between the tire and the runway when they are in contact.
The coefficient of friction between the tire and the surface of the runway depends on, among other factors, the surface texture , the rubber on it, type of aircraft tires, season...
However, the parameter that determines the magnitude of friction in wet surfaces and the speed / friction relation is the micro / macro texture. Microtexture depends on the nature of the aggregates and to improve this magnitude we can use shotblasting or high-pressure water methods, obtaining a good friction on wet pavement in the range of low speeds. The macrotexture, directly responsible for the massive drainage of water, is the thick aggregates texture. The grooving system is designed to solve the bad characteristics of friction on wet pavement and gets texture artificially.
The macrotexture surface requirements that are recommended for new surfaces in terms of depth average is 1 mm., to provide good friction characteristics. But the truth is that in wet runways, with the damage caused by aircrafts traffic,the weather conditions and the rubber deposits, are affected both microtexture and macrotexture.
Consequently, we can say that conditions of low coefficient of friction which enhance hydroplaning can be significantly reduced through transverse grooving. The grooving is currently used in a lot of runways because of its effectiveness in reducing hydroplaning and improving the coefficient of friction.
The grooving can be performed on different pavements, new ones or existing ones, being more profitable than other processes , and it can be done without interfere the airport operation. The grooving does not affec tot the pavement structure.
The results obtained are the following:
1) Improved drainage of water on the runway, allowing water to flow along the grooves and towards the sides of the runway with minimum resistance.
2) Better drainage of the water located between the tire and the surface. The groove provides an artificial macrotexture , which is particularly important at high speeds.
3) Improved coefficient of friction.
5) The aircraft does not have to make circuits around taxiways, avoiding the high economic impact and the traffic problems at the airport.
