Finally, proof of what I saw in NYC

They're about 2 to 3 times the size of common rats (big ones between a pound or two. We called them Sewer Rats because that's their most common habitat where I grew up.

The picture certainly does enhance the perception of it's size, But I can assure you going into a dark storm sewer with tracks of these guys around is an interesting experience if all you've got is a pump pellet gun and you're a young teenager.