They must have one of those machines at Wachusett (small local area in Mass.). There is a single section of one run that always has perfectly symmetrical (and rock hard) bumps. The bump section is about 5 bumps wide all the way from top to bottom. The bumps it makes are pretty rough but they are then smoothed into serviceable bumps by skier traffic.
I found a patent on a grooming machine which can make bumps.
The patent (US 6,351,899) discusses a machine as follows:
With the independent overhead grooming ability provided by the present invention, moguls can now be groomed or made as never before possible with any present rear-mounted tillers currently on the market. Because of the independent overhead position of the tillers, moguls in any kind of pattern, from small and easy to large and more difficult, can be created. The present invention has the ability to carve moguls in a connected series creating a mogul terrain for the satisfaction of beginning to expert skiers.
Below is the ridiculously long link to the page images:http://patimg2.uspto.gov/.piw?docid=US006351899&SectionNum=1&IDKey=D65F85F8 267A&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2%2526Sect2=HITOFF%2526p=1%2526u=/n etahtm
I can email a PDF of the patent if anyone is interested (I work in patent and IP consulting). Just send me a private message with your email.
[img]graemlins/thumbsup.gif[/img][ January 26, 2004, 02:15 PM: Message edited by: NEracerex ]