Notwithstanding the provisions of §§ 46.2-1104 and 46.2-1130, emergency response vehicles, including fire and emergency medical apparatus responding to and returning from an emergency call, may be permitted to exceed the gross weight limit posted on a bridge or culvert, except those maintained by a railroad, provided that a determination has been made by a licensed professional engineer, qualified in the appropriate discipline, that the emergency response vehicle can safely cross that bridge or culvert and that determination has been documented by the issuance of a written permit or letter of authorization by the agency or entity responsible for the maintenance of that bridge or culvert. The permitting agency or entity shall not be held liable for any damage or injury caused as a result of an emergency response vehicle crossing a bridge or culvert while responding to or returning from an emergency call under the conditions specified in the overweight permit pursuant to this section.