This project examined the propensity for and mitigation of hydroplaning on wet pavement surfaces. Its results support the hypothesis that the main factor affecting hydroplaning is the thickness of the water film on the pavement during a rain storm. It developed guidelines for the implementation of three techniques to reduce water film thickness: control of pavement geometry; use of textured surfaces; and effective use of drainage appurtenances.

Water depth is a safety issue on high-speed roadways, and one of the primary concerns is the mechanism known as sheet flow, in which a layer of water flows across an expanse of pavement. Rapid removal of water to minimize sheet flow on the surface must be addressed for the design of new pavements and widened sections and the correction of existing conditions. Even with a typical crowned section, water accumulation on the outer travel lanes can cause problems. The problem may be exacerbated when the surface water flows only to one side or where the low point of sag vertical curves coincides with a flat area of a superelevation transition. There may be additional problems where pavements are rutted.

The objective of this research was to identify effective methods and develop guidelines for improving the surface drainage of pavements. Factors studied included: (a) Geometric factors such as cross slope, longitudinal grade, width of the pavement, and superelevation. (b) Pervious pavements and various pavement surface characteristics. (c) Positive interception techniques such as slotted drains.

The agency final report, "Improved Surface Drainage of Pavements," is available as NCHRP Web Document 16 . Design guidelines were published in September 1999 as NCHRP Research Results Digest 243. The DOS-based software program PAVDRN was originally available on two 1.44 Mb floppy discs compatible with Windows 2000 Professional and Windows XP.

The software is also available here (Pavdrn1.zip and Pavdrn2.zip) as two ZIP files. You will need to extract and copy the contents of Pavdrn1.zip to one 3.5" floppy disk and the contents of Pavdrn2.zip to another (not the actual ZIP files, just the contents), and run setup.exe from the first disk. (It may also be possible to install the software from a removable flash drive.)

A copy of the final report was also distributed to each state department of transportation.