Is it a positive thing if the insurance company for the 18 wheeler accepts liability for property and liability?

While it is not a guarantee they will pay your injury claim, it is good news if the insurance company accepts liability for the property damage. It simply means that their investigation reveals that their insured was sufficiently at fault to subject them to a negative finding on liability at trial. A Plaintiff still has the burden to prove that the claimed injury was related to the accident and that the treatment for the injury was reasonable and customary. Nevertheless, it is a good place to start.