I really like this shot, but it doesn't appear to be a duotone, just because of the color on the sign. It has great composition and angle with good lighting, but think that others will say the same about the color in it. Maybe just a B&W would have helped with this shot.
I like the odd structures involved - the construction equipment and a skateboarder - interesting combo. I will say it looks more like a desat than a duotone - you'll probably get dinged for that as far as score goes.