"Speed Not Reasonable, Act Prudent" 1180A In New York

[quackman]

The state I live in is NY.

I got a speeding(?) ticket a week ago at 11:30 at night. It was in a traffic circle on a highway that runs near Jones Beach Long Island. I was going around a traffic circle a tad fast/fun and about 20 seconds after I left the traffic circle back onto a straight road, a cop pulled me over. He asked me how fast I was going (he didn't specify where) so I said, honestly, "I think up to about 50, sir" he said "Do you know what the speed limit is?"
"This is Ocean Parkway right? 55mph, sir"
"No, it's 20 mph on the traffic circle."
"Oh, I'm sorry, I didn't know, sir."
"Pay attention."
Then he walked back to his car and came back with a ticket that DOES NOT have my speed NOR the speed limit written on it, the only things it states that I did wrong was violate 1180A: "Speed not reasonable, act prudent."
So I mailed in the ticket pleading not guilty... waiting for my court date to happen on June 02, 2008 according to the ticket.
Now, everythign I look up online is about a speeding ticket, but this isn't really a speedingticket, but it IS a moving violation. Does anyone have any practice with/knowledge about this offense?
I went back to the location and it turns out that the speed limit is NOT 20mph on the traffic circle likethe officer said; it's actually 35 mph. The suggested speed is 20mph, a yellow sign, for the circle, but the only speed limit signs right at the circle is 35mph. So... he lied? Would stating this help in court, how do I bring it up? Another piece of evidence on my side is that there were NO other cars around, showing that my speed did not have to be extra low to be reasonable,(the cop was tucked away on teh side of the road out of sight, not on the circle or the road), as it was late at night, and my car showed no signs of being at an unreasonable speed, no tire skidding or anything.

Thanks for reading this, and thanks for any information about this offense and how to contest it in court.

[FlyingRon]

So how fast where you going? Lied or mistaken, he's still got a valid opinion over what is a prudent speed regardless of what the posted or implicit speed limit actually is.

[quackman]

I was going around 40 on the traffic circle, I don't know why he thought it was not prudent though, as I said there were no other cars around.
From your response, I'm judging that there is no good "defense" for this kind of ticket?

[FlyingRon]

So by your own admission, you were speeding by any interpretation of the speed limit.

Violating the posted speed in most states is prima facie evidence of unprudent speed.