Dave,
[:D][C):-)][*]
As another suggestion, consider using stripwood. I suspect it was more common to use wood posts and handrails unless your era is fairly modern. That is also the case with bridge handrails, if they even had them back in the day.
If you feel that the plastic handrails are a lost cause, you could try to straighten them with a hair dryer. Setting the dryer on high and and holding it an inch away from the handrails will definitely melt them. Go slow and you might be able to work out the twist with your hands and slavage the factory parts.
You might try placing them in between something straight, like pieces of glass or metal rulers and see if you can heat them up enough.
They need to cool down in the straight position or else they will just return to their pre-heated shape.