Guide Wheels on Woodies?

I know that steel coasters have three sets of wheels, up stops, road, and guide (side).

I saw a show, I think making of a coaster, and they talked about how there would be a steel plate on top, but on the bottom and side they put them where they were needed.  Also I read somewhere that the guide wheels on woodies weren't wheels, but plates.

So my question, are there running steel plates on all three sides, and wheels on three sides?

Also if they put spring loaded wheels on a woodie, if possible (not sure about space), would that eliminate the side to side motion making a smoother ride.  This would also mean three running plates.  Is this possible and is it a good idea (not claiming as my own), because if it is why don't companies do it?

Check out Dave's site.  He has several good articles on how coasters are designed.

http://capital2.capital.edu/admin-staff/dalthoff/index.html

Some coasters replace "upstop" wheels with plates (saw this on the Giant Dipper last weekend). But I've never heard of guide wheels on a woodie being replaced with plates. (Schwartzkoph did away with guide wheels on some of his coasters by using grooved wheels that fit snugly over the tubular track)
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Yeeee Haaawwww!

*** This post was edited by janfrederick on 8/23/2001. ***

And to answer "why" they would do it: Economics. If a coaster doesn't generate negative Gs, it doesn't really need to rely on upstop wheels. Then the coaster could simply employ guide and running wheels. This is a complete set of wheels that are eliminated from the maintinence schedule. 
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Yeeee Haaawwww!

*** This post was edited by janfrederick on 8/23/2001. ***