If you ran into a parking rail this would likely be considered a claim under collision and not comprehensive since you collided with an object. When you strike an object such as another car, fence, pole, etc it is normally a collision coverage claim.
Comprehensive is for things other than collision and for when things strike your vehicle, like hail, an animal, etc. Comprehensive insurance also covers your car for damage to your car if it is stolen; or damaged by flood, fire or vandalism.
To find out for certain which of your coverages your insurance carrier would place this under check with your insurance agent.
Articles in our Learning Center such as How to Deal With Your Insurance Company Regarding Claims may be of help to you at this time.