What is BS EN 12697-40 about?  
BS EN 12697- 40 is the 40th part in the multi-series of European standards that discusses the bituminous mixtures.
BS EN 12697-40 describes a method to determine the in situ relative hydraulic conductivity, at specific locations, of a road surfacing that is designed to be permeable. An estimate of the average value for the surfacing is obtained from the mean value of a number of determinations on each section of the road.
The test measures the ability to drain water (drain ability) achieved in situ of a surfacing. As such, it can be used as a compliance check to ensure that a permeable surface course has the required properties when it is laid. The test can also be used subsequently to establish the change of drainage ability with time.
For the test to be valid, the surface of the test area should be clean and free from detritus.
Measurements can be made when a road is either wet or dry, but not if it is in a frozen state.
Who is BS EN 12697-40 for? 
BS EN 12697-40 on in situ drainability is useful for: 
- Manufacturers and suppliers of bituminous mixtures and asphalt
- Asphalt refining plants
- Suppliers of construction materials
- Construction and civil engineers
- Contractors
- Road maintenance authorities
Why should you use BS EN 12697-40?  
A permeameter is used to determine the time taken for 4l of water to dissipate through an annular area of the surfacing of pavement under known head conditions. The reciprocal of the outflow time is then used to calculate the relative hydraulic conductivity of the surfacing.
BS EN 12697-40 specifies a method for determining the in situ relative hydraulic conductivity of permeable road surfacing at defined locations. This can assist you in restoring a more natural hydrologic balance and lowering runoff volume.
These provisions are given in BS EN 12697-40 to help you to ensure quality and performance of construction materials, thereby maintaining structural integrity of you engineering works.
