A road underdrainage system is a set of facilities designed to capture, convey and evacuate water that accumulates under or next to the layers that make up a pavement structure, in order to avoid problems such as soil saturation, excessive moisture, erosion or hydrostatic pressure on these layers.

Sección transversal sistema drenaje subterráneo pavimento


Figure 1. Cross section of an underdrainage system implemented in a pavement structure.

 

When an underdrainage system is not implemented in the design of a pavement, saturation of the granular layers, increased pore pressure in the subgrade soil, loss of material due to erosion, among many others, occur. There is a severity factor proposed by Cedergren, which measures the relative damage of pavement performance between dry and wet conditions. For a pavement section with a moderate severity factor of 10, if 10% of the time is saturated, the service life can be reduced by half:

 

Gráfico vida útil pavimento según factor severidad

Figure 2. Service life of a pavement with respect to the time that the section is saturated
(Source: Cedergren, H.R. 1987, Drainage of highway and airfield pavementsRobert E Krieger Publishing Co, FL).

 

He longitudinal underdrain is in charge of capturing flows converging horizontally and guiding them in a direction parallel to the road.

He transverse underdrainage is in charge of capturing upward water flows and conveying them to the longitudinal underdrainage system. It also prevents the access of subsurface water to the layers of the pavement structure.

 

Esquema técnico drenaje subterráneo con tuberías perforadas

Figure 3. Transverse and longitudinal underdrainage in a pavement underdrainage system.

 

Implement a underdrainage system on a road provides numerous benefits that improve both the durability and safety of the road. The most representative ones are listed below:

  1. Improved soil stability:

 Controls the water table and excess groundwater that can cause differential settlement or landslides, especially in sloping or unstable terrain. Underdrain stabilizes the ground and prevents structural failure.

  1. Prolongation of pavement life:

Water is one of the factors that deteriorate roads the most. If it accumulates in the subgrade, it weakens the granular layers of the pavement, causing deformations, cracks and potholes. A good subgrade system prevents this damage by keeping the supporting soil dry.

  1. Reduced maintenance costs:

By avoiding severe structural damage to the pavement, the frequency and magnitude of necessary repairs is reduced, resulting in significant long-term savings.

  1. Improves the functioning of surface drainage systems:

 The following photographs show the construction process of a longitudinal underdrainage system using PERMADRAIN tubular geodrain and DRAINPIPE perforated pipe for underdrainage.

Tubería negra instalada en zanja excavada tierra Excavación en zanja con grava y geotextil negro

 

The following photographs show the construction process of a transverse underdrainage system at the base of the pavement using planar geodrain. PERMADRAIN

Obrero en chaleco naranja instalando asfalto en carretera Trabajadores colocando asfalto en carretera de montaña