The base sealing ring simulates a tire footprint. A measured volume of water is released in the center of the sealing ring while an electronic timer indicates how long it takes the water to pass through texture voids in the pavement under the seal. This test also provides a graphic visual display of escaping water.

Macrotexture is effective for drainage only when surface voids are connected by water flow channels below the tire contact points. The Hydrotimer shows the effectiveness of the surface voids to channel water from under the tire footprint.