Bridges on private roads need to hold the load of a fire truck. If you are designing a bridge for your driveway the bridge will need to be engineered to meet Federal Highway Standards - HS20 load requirements.
If you have an existing bridge that your driveway must cross that has not been approved by the Fire Marshal’s Office in the last 5 years, you will need an Engineer’s observation report showing that the bridge meets this HS-20 load requirement.