I live in Northern Ontario, Cda.. I volunteer at a not for profit
community group and last year we installed a wheelchair ramp (made of
wood-cedar with two 15' and 30' rise sections ). Unfortunatly the
first winter we had to close the ramp as it became too dangerous to
walk on with the ice and snow. I am looking for a solution to this
problem so that we might use the ramp this winter. Thanks

Dear guilford1-ga,

I am a wheelchair user myself so I know the problems - albeit here in
the UK we have nothing like the winters you have!

I have had a look and there are three main products. They range from
mats, grippers, to heated rubber tracks which are obviously the most
expensive. Mats are sometimes suitable, but the deeper they are, the
harder it is to propel  the wheelchair over it. Here are examples of
the products but not necessarily in your location.

Grippers. (explore each of the sites to see the different types on offer)
http://www.handiramp.com/non-skid_water.htm
http://www.ramps-ramps-ramps.com/AL_Non-Skid.htm
(include all the links on the bottom right> Non-Skid Information.

http://www.gripstrut.com/catalog/online/catindex.htm
http://www.mcnichols.com/products/grating/plank/diamond/

Mats. These seem to be laid over the snow?s surface so may not be
suitable in your situation.
http://www.abledata.com/abledata.cfm?pageid=113583&top=0&productid=74275&trail=0
http://www.improvementscatalog.com/product.asp?product=276133zz&dept%5Fid=12450

Heated mats.
This is a heated mat called Heat Trak. Costings etc. are supplied on
the page.  There is an example of a wheelchair user.
http://www.heatersplus.com/heattrakmat.htm
Similar product from Martinson-Nicholls
http://www.floormat.com/heated-matting.html

This site on ramp construction suggest that, ?on wooden ramps,
treatments that are used include commercially-available "grit" tapes,
strips of rolled roofing or shingling, or laying down coats of
polyurethane into which sand is sprinkled.? But they do not make any
suggestions about dealing with severe snow or ice.
http://www.wheelchairramp.org/rampman/manual/ramp09.htm

I hope this answers your question. If it does not, or the answer is
unclear, then please ask for clarification of this research before
rating the answer. I shall respond to the clarification request as
soon as I receive it.
Thank you
answerfinder

I would consider using "expanded metal" on the ramp in winter:

http://www.mcnichols.com/products/grating/expanded/standard/

Of course, snow would have to be removed, and hopefully there is
nothing against using salt to melt ice and snow caught in the mesh of
the grating.