how to form exterior cip concrete stair with radius

huangyhg

how to form exterior cip concrete stair with radius
gents-
i have a client who wants to install a cast-in-place concrete stair on grade on the exterior of a new restaurant addition.  in plan, the stair is about 45 feet long, about 6' wide, and the nosing of each tread is to be formed in an arc with about a 42 foot radius.  its unusual.
is it feasible to form stair treads in the field with such a radius?  
yes, experienced formwork carpenters can work wonders with plyform. the problem is to find the carpenters with that experience level & to pay the price.
i have used azek material in the past to form stairs like that, that were wider than 8'.  makes a nice smooth finish with easy release from the concrete.