Aquaplaning (see friction below as well). Why do we worry about aquaplaning? For an introduction to the problem, Capt. Ranganathan has written an informative article, and for more technical discussion on aquaplaning and (from PPrune) a discussion on speed for hydroplaning and discussion on Qantas QF1 overrun and discussion on the effect of grooving on whether a runway is wet or "dry". Not trying to pinch PPRUNE's thunder, just making sure that their words of wisdom don't get lost with the passage of time. If you're serious about aviation, go there and sign up - http://www.pprune.org
Article from FLIGHT SAFETY AUSTRALIA on managing slippery runways.
and friction (see aquaplaning above and texture just below). Introductory discussion on comparison between methods. There is not, at present, a common friction index for all ground friction measuring devices. I'm not sure if this USAF chart should be used to convert between measuring devices, since there is general concern that devices do not measure repeatably and reproducibly. Don't mix up wet pavement friction and snow friction - they are different in concept. Note that the decelerometers (Tapley or brakemeter) are for snow covered pavements, not specifically not for wet pavements or slush covered ones. Presentation by ERAA on friction and snow - one of the conclusions from this paper was: “There is no overall accepted certification to operational correlation between mu meters and airplanes”; it's been lost on their website but if you click here it might be found it again. Discussion on the effect of heavy rain (thunderstorms) on braking action and friction here.
and texture. Texture (both microtexture and macrotexture) are important contributions to good wet weather friction. A lack of either macrotexture OR microtexture (or both) affects the ability of the runway to alleviate fluid pressure (i.e. water pressure building up under the tyres).
There is an old but great NASA paper on "Wet Runways" by Walter Horne (NASA TM X-72650; 1975) (e-mail me if you want a copy) which defines and discusses some important parameters associated with aircraft stopping and directional control performance on wet runways. The major elements affecting tyre/ground traction for jet transport aircraft are identified and described in terms of atmospheric, pavement, tyre, aircraft system and pilot performance factors or parameters. Note: being American, there is more written in the paper about tires than tyres.
When water is deposited on runways during rainstorms, a water removal or drainage problem is created at tyre/pavement interfaces of the moving aircraft.
Birds Bird strikes
The stationary water intercepted by the translating/rotating aircraft tires must be rapidly expelled from the tyre/pavement contact zone or viscous and dynamic water pressures build-up with increasing ground speed. When the average water pressure developed between the tyre and pavement surface equals the tyre inflation pressure, total dynamic or viscous hydroplaning occurs, and the tyre is supported on a water layer or film and is no longer in direct contact with the pavement. In this situation tyre braking and cornering forces are almost zero, due to the inability of a fluid (water) to support shear forces of any appreciable magnitude.
Carparking This is at a premium at many airports, and a significant source of income for the major airports. Some places - like Tu****e - are more like carparks with a runway. Well I suppose this is slightly better than being a shopping mall with a runway like F***rt. Or a business where the runway is simply a nuisance and never-ending cost centre - like Bri**ol. The cost of providing carparking varies substantially, and the multi-story carparks can really cost a lot. Click here for a budget carpark costing.